I checked stations for the US people who posted here. I didn't feel like converting units and I don't know how to pull foreign data, sorry metric people. Most places have seen a 1F diurnal, but none of the six saw a 0 degree range in over 100 years. Is it that rare or does the NWS change them to 1F?
Rochester (New York), records from 1871. Range from 1 to 50F.
Lowest range is 1, mostly in winter.
1922-11-21 33/32, trace snow
1956-01-10 37/36, 0.02" rain
1982-02-21 34/33, 3.5" snow
2010-12-23 26/25, 0.1" snow
Several days with 2F, most recent was last winter.
2020-01-28, 32/30 with 0.14" total precip and 0.9" snow
Highest range is 50, in winter or spring
1875-12-20 42/-8
1901-01-20 48/-2
1903-04-30 85/35, trace rain
1918-02-20 52/ 2, 0.3" snow
Largest since 2000 was 48.
2009-04-24 82/34, trace rain
Fort Collins, records since 1893. Range is 1 to 75F.
Lowest range is 1.
1895-03-30 33/32 with 1.5" snow
1967-12-13 15/14 with 5.1" snow
Some notable days with 2F diurnals:
1902-09-21 44/42 with 4.34" rain (warmest, wettest)
1897-11-28 13/11 and dry (coldest)
Lowest since 2000 is 3
2017-09-24 48/45, 0.20" rain
Largest is 75. Big swings are most likely in late winter.
1899-02-12 37/-38 (75F)
1919-12-10 51/-23 (74F)
1943-01-20 55/-13 (68F)
Since 2000, the largest
2015-01-05 59/ 2 (57F)
2014-01-24 61/ 5 (56F)
Seattle, records since 1894. Range is 1 to 40. Unlike the previous two places, the big diurnals happen with warm weather.
Five days with 1F diurnal, all in winter.
1922-02-23 39/38 dry
1925-12-23 53/52 0.01" rain
1971-01-23 44/43 trace rain
1974-01-28 45/44 0.05" rain
2014-01-13 51/50 dry
56 days with 2F, 276 days with 3F. Small diurnals are not rare.
Three days with 40F diurnal, all dry and warm
1951-09-15 87/47
1960-08-09 99/59
1974-09-14 88/48
Largest since 2000
2007-07-11 98/61
Milwaukee, records since 1871. Range is 1 to 49.
14 days have 1F diurnals, and it was most common in the 1870s. I think data was only taken a few times a day back then so it was easier to get small diurnals. Most of these days were in the 30s with rain or a rain/snow mix. Some notable ones:
1871-02-21 28/27 and dry (coldest)
1874-04-27 35/34 and dry (latest in spring**)
I am suspicious of the 35/34 on April 27th. With no rainfall and high sun angle there should be a larger range.
1892-11-01 45/44 with 0.48" rain (warmest, earliest in fall)
1970-12-11 33/32 with 0.71" precip and 3.8" snow (wettest, snowiest)
1998-03-18 36/35 and 0.47" rain (recent)
2006-01-02 40/39 and 0.65" rain (recent)
The last 2F diurnal was last winter. This happened 158 times so roughly once a year.
2019-11-30 39/37 0.52" rain
While rare, these days can happen even in warm months. The only months that have avoided a 2F range are June and July.
1904-08-19 62/60 with 1.44" rain
1914-08-28 62/60 with trace rain
1950-08-30 63/61 with 0.07" rain
1957-05-19 43/41 and 0.37" rain
1990-05-20 47/45 and trace rain
Largest range was 49, four times. Two of these days were warming up, two were cooling down.
1872-02-14 45/-4, 0.02" total precip
1916-01-05 49/ 0, 0.05" rain
1930-04-10 90/41, dry
1934-01-28 45/-4, dry
The largest since 2000 was 46.
2003-04-15 86/40, trace precip
Norman 3SSE (Oklahoma), records since 1895. Range is 1 to 71.
Two days with a 1 degree range.
1930-10-06 61/60 and 1.68" rain
1956-03-13 38/37 and 0.07" rain
2 degrees is more common, it happened twice in 2019. The last summer day with a 2F range was in 2007.
2019-01-02 26/24 dry
2019-02-20 33/31 0.15" rain, trace snow
2007-06-26 73/71 and 0.99" rain
The largest range by far was in 1904. Second place was 1933 and several other days near it.
1904-03-03 91/20 dry (71F)
1933-02-07 59/-3 0.2" snow (62F)
2008-12-15 74/16 trace snow (58F, largest since 2000)
Miami, records since 1895. Range from 2 to 41. Unlike the other stations Miami hasn't recorded a 1F diurnal. The stronger winter sun may be the reason.
17 days have recorded 2 degree diurnals. Most of these are in the low sun months of October through February. A few notable ones:
1906-08-05 82/80 and dry (warmest, only one in summer)
1927-04-12 74/72 and dry (only one in spring)
1973-02-19 64/62 and 0.30" rain (coldest)
1969-10-30 77/75 and 3.48" rain (wettest)
Smallest since 2000 is 3
2008-09-10 86/83 and trace rain
Largest is 41. The early 1900s had the largest swings. Did the station move in the early 1900s?
1902-03-05 85/44 (41F)
1905-01-26 70/29 (41F)
1904-01-15 75/36 (39F)
1903-11-29 78/39 (39F)
Largest since 2000 is only 33.
2017-01-07 87/54 and 0.59" rain
Finally got around to screen it.
