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Post by nei on Aug 1, 2018 15:31:25 GMT -5
I've download hourly weather data for my location as well as a few stations. Curiously how often we got humid heat vs dry heat and couldn't find a frequency comparison for just humid & dry heat on any website like the iowstate data plotter or weatherspark. Heat map of temperature / dewpoint combinations in Chicopee, MA; closest station which has hourly data. Only looked at 5 am to 10 pm to mask out nights when the temperature don't change as much and often hover around the dewpoint, which would make a peak at the cooler and high relative humidity combinations.  left line peaking corresponds to near or at 100% humidity. At hotter temperatures (> 76°F), you can see moderate high dewpoints (58 to 72°F) are all about equally likely, but the most common ones are in the mid to high 60s. But dewpoints much more below average happen more while there's more of a cutoff at high dewpoints. For moderately hot temperatures 80-84°F, dewpoints 20th percentile: 56°F 50th percentile/median: 63°F 80th percentile: 69°F including cooler temperatures in the 70s and 60s barely changes the percentiles, which makes sense since the cooler temperatures are probably from morning or evening with similar dews to hotter times of the day when it's in the 80s. For looking at only "real heat" (> 86°F / 30°C) 20th percentile: 60°F 50th percentile/median: 66°F 80th percentile: 70°F so dry heat happens but it's not that often, at most 20% of the time, if 60°F is your threshold for not humid. Just looking at hours when it's above 86°F, you can see the mode doesn't match the median; heat with a dewpoint in the high 60s is the most common, but much lower humidity can happen.  and dewpoints when raining; symmetric around the mean. Thought it'd be higher  ========================================= Don't have many other stations to look at, I have Miami. Had to change the scale lol  not much variation. A dewpoint higher than 26.5°C (79.7°F) occurs about 1.8% of the time [dewpoints are rounded to the nearest °F so not exact]. For Chicopee, a dewpoint 73°F or higher occurs 2% of the time; only 9 hours have recorded a dewpoint of 79°F or higher. |
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Post by AJ1013 on Aug 1, 2018 15:34:49 GMT -5
I've download hourly weather data for my location as well as a few stations. Curiously how often we got humid heat vs dry heat and couldn't find a frequency comparison for just humid & dry heat on any website like the iowstate data plotter or weatherspark. Heat map of temperature / dewpoint combinations in Chicopee, MA; closest station which has hourly data. Only looked at 5 am to 10 pm to mask out nights when the temperature don't change as much and often hover around the dewpoint, which would make a peak at the cooler and high relative humidity combinations. left line peaking corresponds to near or at 100% humidity. At hotter temperatures (> 76°F), you can see moderate high dewpoints (58 to 72°F) are all about equally likely, but the most common ones are in the mid to high 60s. But dewpoints much more below average happen more while there's more of a cutoff at high dewpoints. For moderately hot temperatures 80-84°F, dewpoints 20th percentile: 56°F 50th percentile/median: 63°F 80th percentile: 69°F including cooler temperatures in the 70s and 60s barely changes the percentiles, which makes sense since the cooler temperatures are probably from morning or evening with similar dews to hotter times of the day when it's in the 80s. For looking at only "real heat" (> 86°F / 30°C) 20th percentile: 60°F 50th percentile/median: 66°F 80th percentile: 70°F so dry heat happens but it's not that often, at most 20% of the time, if 60°F is your threshold for not humid. Just looking at hours when it's above 86°F, you can see the mode doesn't match the median; heat with a dewpoint in the high 60s is the most common, but much lower humidity can happen. and dewpoints when raining; symmetric around the mean. Thought it'd be higher ========================================= Don't have many other stations to look at, I have Miami. Had to change the scale lol  not much variation. A dewpoint higher than 26.5°C (79.7°F) occurs about 1.8% of the time [dewpoints are rounded to the nearest °F so not exact]. For Chicopee, a dewpoint 73°F or higher occurs 2% of the time; only 9 hours have recorded a dewpoint of 79°F or higher. Can you do a dewpoint frequency for Miami for all hours (like the one you have for “hours above 86F” but for just all hours all year? |
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Post by knot on Aug 1, 2018 15:34:53 GMT -5
Humid heat is pretty much non-existant up this way, as with all of Western NSW. Still plenty of thunderstorm activity (due to elevation), however!  |
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Post by nei on Aug 1, 2018 15:36:49 GMT -5
Can you do a dewpoint frequency for Miami for all hours (like the one you have for “hours above 86F” but for just all hours all year? do you want all hours, or exclude most of the night like I did? |
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Post by AJ1013 on Aug 1, 2018 15:38:44 GMT -5
Can you do a dewpoint frequency for Miami for all hours (like the one you have for “hours above 86F” but for just all hours all year? do you want all hours, or exclude most of the night like I did? All hours should be fine. I’m thinking like a bar graph of Miami’s dp frequency for the whole year. |
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Post by Babu on Aug 1, 2018 15:39:36 GMT -5
The highest humidity is generally in the end of heatwaves here. The time of day doesn't really matter for DP's here except there are never 22'C dp's in the coldest hour. What southeastern Sweden has seen is if a humid day gets 33'C temps, the hottest hours are rather dry, below 15'C DP generally. This trend has been even more pronounced in western Sweden. We haven't had truly hot days here since the humidity got high though so don't know if the same applies to here.
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Post by Steelernation on Aug 1, 2018 15:52:34 GMT -5
nei what plot did you use? I was on the Iowa state data plotter but I couldn’t find an option that made a chart like that.
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Post by nei on Aug 1, 2018 15:54:01 GMT -5
nei what plot did you use? I was on the Iowa state data plotter but I couldn’t find an option that made a chart like that. I made it myself since I couldn't find it in the Iowa State data plotter. Got the data from the IowaState website, also available from the NCDC. |
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Post by Steelernation on Aug 1, 2018 16:01:14 GMT -5
I made it myself since I couldn't find it in the Iowa State data plotter. Got the data from the IowaState website, also available from the NCDC. Ok. I’m too lazy to make my own charts and graphs so could you make a graph for Rochester like the one you made? |
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Post by nei on Aug 1, 2018 16:25:37 GMT -5
I made it myself since I couldn't find it in the Iowa State data plotter. Got the data from the IowaState website, also available from the NCDC. Ok. I’m too lazy to make my own charts and graphs so could you make a graph for Rochester like the one you made? I'll do Rochester later, here's the annual one AJ1013 requested.  percentiles for 80-84°F heat: 20th: 68°F 50th: 73°F 80th: 75°F surprised that Miami rarely gets dry heat outside of summer, hope I didn't make a mistake. A histogram of all temperatures above 86°F  or just all temperatures over the whole year  |
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Post by Benfxmth on Apr 21, 2020 10:43:43 GMT -5
So I made plots for frequencies of dew points by temperature for Rome, I was curious of how common is humid heat versus dry heat. Now it's unfortunate that they only have hourly data since 2011, thus why the plots look inconsistent; if anyone in here knows a better site for downloading hourly data, let me know. If you want me to make plots for other cities, or if you want the script(s) that I used, PM me. Here we go: **Heat map of Rome Ciampino (the closest official station to me):**  As you can see, on average, dew points tend to fall slightly during the day, and humid heat (if 15°C is your cutoff for humid or dry heat) is slightly more common than dry heat, and dew points above 23°C or below 10°C are rare, more rare than I thought. Percentiles for a typical summer day of 31°C: 99th percentile: 22°C 90th percentile: 20°C 75th percentile: 18°C 50th percentile (mean): 16°C 25th percentile: 14°C 10th percentile: 11°C 1st percentile: 7°C **Fiumicino (at the coast):**  The coast is muggier than further inland, and high dew points are more common. Percentiles for a typical summer day of 29°C: 99th percentile: 24°C 90th percentile: 22°C 75th percentile: 21°C 50th percentile (mean): 19°C 25th percentile: 16°C 10th percentile: 14°C 1st percentile: 8°C |
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Post by Morningrise on Apr 22, 2020 11:19:03 GMT -5
Don't have any data for it, but dry heat is overwhelmingly more common than humid heat out here. We do get a few days with tropical humidity each summer, and dew points in the 15C to 18C range happen on a semi-regular basis, but overall it tends to be on the dry side by far.
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Post by Benfxmth on Apr 22, 2020 12:35:13 GMT -5
Don't have any data for it, but dry heat is overwhelmingly more common than humid heat out here. We do get a few days with tropical humidity each summer, and dew points in the 15C to 18C range happen on a semi-regular basis, but overall it tends to be on the dry side by far. Here is a plot for Saskatoon:  Truly tropical-like dew points (above 20°C) are rare, though dew points in the 14-17°C are not rare like you said before; the percentiles for a typical July day of 25°C are the following: 99th percentile: 19°C 90th percentile: 16°C 75th percentile: 14°C 50th percentile (mean): 11°C 25th percentile: 8°C 10th percentile: 6°C 1st percentile: 1°C Data is for since 1957. |
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Post by Morningrise on Apr 23, 2020 9:31:25 GMT -5
Don't have any data for it, but dry heat is overwhelmingly more common than humid heat out here. We do get a few days with tropical humidity each summer, and dew points in the 15C to 18C range happen on a semi-regular basis, but overall it tends to be on the dry side by far. Here is a plot for Saskatoon: Truly tropical-like dew points (above 20°C) are rare, though dew points in the 14-17°C are not rare like you said before; the percentiles for a typical July day of 25°C are the following: 99th percentile: 19°C 90th percentile: 16°C 75th percentile: 14°C 50th percentile (mean): 11°C 25th percentile: 8°C 10th percentile: 6°C 1st percentile: 1°C Data is for since 1957. Very interesting! Pretty much lines up with what I was expecting. Personally I'd prefer dew points in the 15C to 18C range to be more common (as that feels just about perfect for me on a warm summer day), and I also enjoy truly tropical humidity from time-to-time and would like a bit more of that too. Winnipeg generally does pretty well in that regard and has my favorite summers of any city in the prairie provinces, but at least we're still better off than Edmonton and Calgary. |
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Post by Benfxmth on Apr 23, 2020 9:35:04 GMT -5
Here is a plot for Saskatoon: Truly tropical-like dew points (above 20°C) are rare, though dew points in the 14-17°C are not rare like you said before; the percentiles for a typical July day of 25°C are the following: 99th percentile: 19°C 90th percentile: 16°C 75th percentile: 14°C 50th percentile (mean): 11°C 25th percentile: 8°C 10th percentile: 6°C 1st percentile: 1°C Data is for since 1957. Very interesting! Pretty much lines up with what I was expecting. Personally I'd prefer dew points in the 15C to 18C range to be more common (as that feels just about perfect for me on a warm summer day), and I also enjoy truly tropical humidity from time-to-time and would like a bit more of that too. Winnipeg generally does pretty well in that regard and has my favorite summers of any city in the prairie provinces, but at least we're still better off than Edmonton and Calgary. Have you made a dream climate? I personally prefer dew points on the 50s F (on average), but dew points as high as 75°F or as low as 40°F happen every year on my dream climate in summer. |
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Post by Morningrise on Apr 23, 2020 13:33:29 GMT -5
Very interesting! Pretty much lines up with what I was expecting. Personally I'd prefer dew points in the 15C to 18C range to be more common (as that feels just about perfect for me on a warm summer day), and I also enjoy truly tropical humidity from time-to-time and would like a bit more of that too. Winnipeg generally does pretty well in that regard and has my favorite summers of any city in the prairie provinces, but at least we're still better off than Edmonton and Calgary. Have you made a dream climate? I personally prefer dew points on the 50s F (on average), but dew points as high as 75°F or as low as 40°F happen every year on my dream climate in summer. Haven't posted one yet, no, though I should really get on that. I have a few different variations that I would be content with, rather than one single specific dream climate. |
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Post by Benfxmth on Sept 26, 2023 19:29:14 GMT -5
Plots for June, July and August here (doing 1991-2020 for this one though). I'll exclude nighttime, as that skews the results some, especially in cooler temps (again, special thanks to nei for that script) In a typical heatwave (95-97°F, which is around the annual mean maximum; box centered at 96°F, for July and August; doing 94°F for June since heat potential is slightly lower), the percentiles are the following when the temp is in that range...goes to show there isn't much of a dewpoint drop for typical heatwaves (with mid to upper 90s highs) June99th percentile: ~79°F 90th percentile: ~75°F 75th percentile: ~73°F Mean: ~71°F 25th percentile: ~67°F 10th percentile: ~64°F 1st percentile: ~57°F (extrapolating a bit, could be a little off)  July99th percentile: ~82°F 90th percentile: ~79°F 75th percentile: ~76°F Mean: ~74°F 25th percentile: ~71°F 10th percentile: ~69°F 1st percentile: ~63°F  August99th percentile: ~82°F 90th percentile: ~78°F 75th percentile: ~75°F Mean: ~73°F 25th percentile: ~70°F 10th percentile: ~68°F 1st percentile: ~62°F  JJA as a whole  There does, however, appear to be a bit of a downward trend for the very hottest temps (for JJA as a whole, the mean dewpoint for temps above 100°F appears to be in the lower 70s range) due to downslope warming/drying/subsidence from the Appalachians as those temps are brought by heat domes from the Plains moving south. Those daytime plots are also interesting in that it confirms that mid-80s temps during the days are most likely to see very low (60s or below) dewpoints in midsummer, due to the occasional cold front that brings dry air; whereas sub-80°F temps tend to be either in the morning or are rain-cooled. There does appear to be a slightly higher potential for very humid heat in August for the hottest heatwaves due to less drying from mixing, the slight drop in means from July is mostly from slightly cooler average temps. ------------------- PWS for July/August 2022 and 2023, I'll do percentiles for near normal highs for this one. Trend appears similar (except a couple of °F higher mean dewpoints due to more vegetation and river moderation). 2022 2023 At 86°F (near the daily average warmest hourly temp), percentiles for both years are roughly the following; 90th percentile: ~80°F Mean: ~75°F 10th percentile: ~72°F The data lines up with what I felt: summer 2023 had similar mean dewpoints, but was more variable: more dry heat from postfrontal downslope drying/warming but also slightly more very high dewpoints (such as the humid heatwave in mid-August). |
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Post by desiccatedi85 on Sept 27, 2023 16:53:38 GMT -5
Plots for June, July and August here (doing 1991-2020 for this one though). I'll exclude nighttime, as that skews the results some, especially in cooler temps (again, special thanks to nei for that script) In a typical heatwave (95-97°F, which is around the annual mean maximum; box centered at 96°F, for July and August; doing 94°F for June since heat potential is slightly lower), the percentiles are the following when the temp is in that range...goes to show there isn't much of a dewpoint drop for typical heatwaves (with mid to upper 90s highs) June99th percentile: ~79°F 90th percentile: ~75°F 75th percentile: ~73°F Mean: ~71°F 25th percentile: ~67°F 10th percentile: ~64°F 1st percentile: ~57°F (extrapolating a bit, could be a little off) July99th percentile: ~82°F 90th percentile: ~79°F 75th percentile: ~76°F Mean: ~74°F 25th percentile: ~71°F 10th percentile: ~69°F 1st percentile: ~63°F August99th percentile: ~82°F 90th percentile: ~78°F 75th percentile: ~75°F Mean: ~73°F 25th percentile: ~70°F 10th percentile: ~68°F 1st percentile: ~62°F JJA as a whole There does, however, appear to be a bit of a downward trend for the very hottest temps (for JJA as a whole, the mean dewpoint for temps above 100°F appears to be in the lower 70s range) due to downslope warming/drying/subsidence from the Appalachians as those temps are brought by heat domes from the Plains moving south. Those daytime plots are also interesting in that it confirms that mid-80s temps during the days are most likely to see very low (60s or below) dewpoints in midsummer, due to the occasional cold front that brings dry air; whereas sub-80°F temps tend to be either in the morning or are rain-cooled. There does appear to be a slightly higher potential for very humid heat in August for the hottest heatwaves due to less drying from mixing, the slight drop in means from July is mostly from slightly cooler average temps. ------------------- PWS for July/August 2022 and 2023, I'll do percentiles for near normal highs for this one. Trend appears similar (except a couple of °F higher mean dewpoints due to more vegetation and river moderation). 20222023At 86°F (near the daily average warmest hourly temp), percentiles for both years are roughly the following; 90th percentile: ~80°F Mean: ~75°F 10th percentile: ~72°F The data lines up with what I felt: summer 2023 had similar mean dewpoints, but was more variable: more dry heat from postfrontal downslope drying/warming but also slightly more very high dewpoints (such as the humid heatwave in mid-August). Random observation, but the plots generally look visually like the shape of North Carolina, especially those first four.
Can you do one for Atlanta? I'm too busy with other stuff.
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Post by Kaleetan on Sept 28, 2023 12:13:30 GMT -5
Plots for June, July and August here (doing 1991-2020 for this one though). I'll exclude nighttime, as that skews the results some, especially in cooler temps (again, special thanks to nei for that script) In a typical heatwave (95-97°F, which is around the annual mean maximum; box centered at 96°F, for July and August; doing 94°F for June since heat potential is slightly lower), the percentiles are the following when the temp is in that range...goes to show there isn't much of a dewpoint drop for typical heatwaves (with mid to upper 90s highs) June99th percentile: ~79°F 90th percentile: ~75°F 75th percentile: ~73°F Mean: ~71°F 25th percentile: ~67°F 10th percentile: ~64°F 1st percentile: ~57°F (extrapolating a bit, could be a little off) July99th percentile: ~82°F 90th percentile: ~79°F 75th percentile: ~76°F Mean: ~74°F 25th percentile: ~71°F 10th percentile: ~69°F 1st percentile: ~63°F August99th percentile: ~82°F 90th percentile: ~78°F 75th percentile: ~75°F Mean: ~73°F 25th percentile: ~70°F 10th percentile: ~68°F 1st percentile: ~62°F JJA as a whole There does, however, appear to be a bit of a downward trend for the very hottest temps (for JJA as a whole, the mean dewpoint for temps above 100°F appears to be in the lower 70s range) due to downslope warming/drying/subsidence from the Appalachians as those temps are brought by heat domes from the Plains moving south. Those daytime plots are also interesting in that it confirms that mid-80s temps during the days are most likely to see very low (60s or below) dewpoints in midsummer, due to the occasional cold front that brings dry air; whereas sub-80°F temps tend to be either in the morning or are rain-cooled. There does appear to be a slightly higher potential for very humid heat in August for the hottest heatwaves due to less drying from mixing, the slight drop in means from July is mostly from slightly cooler average temps. ------------------- PWS for July/August 2022 and 2023, I'll do percentiles for near normal highs for this one. Trend appears similar (except a couple of °F higher mean dewpoints due to more vegetation and river moderation). 20222023At 86°F (near the daily average warmest hourly temp), percentiles for both years are roughly the following; 90th percentile: ~80°F Mean: ~75°F 10th percentile: ~72°F The data lines up with what I felt: summer 2023 had similar mean dewpoints, but was more variable: more dry heat from postfrontal downslope drying/warming but also slightly more very high dewpoints (such as the humid heatwave in mid-August). Can you do one for Madison? |
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Post by Benfxmth on Sept 28, 2023 14:25:15 GMT -5
I'll split into two different posts. desiccatedi85 Plots for Atlanta (KATL) June(For around the monthly mean max, 92°F which roughly translates to 94°F highs) 99th percentile: ~75°F 90th percentile: ~73°F 75th percentile: ~70°F Mean: ~67°F 25th percentile: ~63°F 10th percentile: ~59°F 1st percentile: ~50°F (extrapolating a bit, could be a little off) (Near the average high, 86°F) 90th percentile: ~72°F Mean: ~67°F 10th percentile: ~59°F  July(For around the monthly mean max, 94°F which roughly translates to 96°F highs) 99th percentile: ~77°F 90th percentile: ~73°F 75th percentile: ~71°F Mean: ~68°F 25th percentile: ~64°F 10th percentile: ~61°F 1st percentile: ~54°F (extrapolating a bit, could be a little off) (Near the average high, 88°F) 90th percentile: ~75°F Mean: ~70°F 10th percentile: ~64°F  August(For around the monthly mean max, 93°F which roughly translates to 95°F highs) 99th percentile: ~77°F 90th percentile: ~73°F 75th percentile: ~71°F Mean: ~68°F 25th percentile: ~65°F 10th percentile: ~61°F 1st percentile: ~55°F (extrapolating a bit, could be a little off) (Near the average high, 87°F) 90th percentile: ~74°F Mean: ~69°F 10th percentile: ~62°F  |
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