Hottest avg high by state here in the US (from the book "Extreme Weather" by Christopher C. Burt, if there's any inaccuracies feel free to correct me). I'm also gonna put where within the state the location is.
Alabama: Bessemer; 93.6 F (34.2 C) in July. Located in the central part of the state about 40 miles NW of Montgomery.
Alaska: Central; 73.9 F (23.3 C) in July. Located in the east-central part of the state, somewhat close to the border with Yukon.
Arizona: Willow Beach; 112.5 F (44.7 C) in July. Located in the northwestern part of the state on the NV border.
Arkansas: Blue Mountain Damn; 94.7 F (34.8 C) in August. Located in the west-central part of the state close to the OK border.
California:
Death Valley; 114.9 F (46.1 C) in July. Located in the southeastern part of the state near the NV border. Although
firebird1988 pointed out that the average high is actually 47.2 C here.
Colorado: Uravan; 94.9 F (34.9 C) in July. Located in the SW part of the state close to the UT border.
Connecticut: Stamford; 85.4 F (29.7 C) in July. Located in the SW part of the state near NYC.
Delaware: Newark; 87.6 F (30.9 C) in July. Located in the northern part of the state close to the MD border.
Florida: Lakeland; 94.6 F (34.8 C) in July. Located in the central part of the state between Tampa and Orlando. Not sure how accurate this one is.
Georgia: Waycross; 94.7 F (34.8 C) in July. Located in inland SE GA near the FL border.
Hawaii: Honolulu Airport; 88.9 F (31.6 C) in July. Located on Oahu Island.
Idaho: Glens Ferry; 95.2 F (35.1 C) in July. Located in the SW part of the state somewhat close to Boise.
Illinois: Kaskaskia River Lock; 91.2 F (32.9 C) in July. Located in the SW part of the state right on the MO border.
Indiana: Evansville Museum; 90.5 F (32.5 C) in July. Located in the extreme SW corner of the state near the KY and IL borders.
Iowa: Keosauqua; 88.3 F (31.3 C) in July. Located in the far southeastern part of the state near the MO and IL borders.
Kansas: Wilmore 16 SE; 95.9 F (35.5 C) in July. Located in the far south-central part of the state near the OK border.
Kentucky: Gilbertsville Dam; 93.6 F (34.2 C) in July. Located in the far western part of the state near the IL, MO, and TN borders.
Louisiana: Calhoun Research Station; 94.5 F (34.7 C) in August. Located in the northeastern part of the state.
Maine: Sanford; 82.5 F (28.1 C) in July. Located in the far southern part of the state near the NH border, inland from Portland.
Maryland: Baltimore; 90.6 F (32.6 C) in July. This is a well-known city.
Massachusetts: Chester; 85.5 F (29.7 C) in July. Located in the southwest part of the state somewhat near the CT and NY borders.
Michigan: Dearborn; 85.7 F (29.8 C) in July. Located in the far southeastern part of the state near the OH border.
Minnesota: Chaska; 85.8 F (29.9 C) in July. Located in the south-central part of the state near the Twin Cities.
Mississippi: Belzoni; 93.0 F (33.8 C) in July. Located in the west-central part of the state.
Missouri: Kennett; 92.8 F (33.7 C) in July. Located in the far southeastern part of the state near the AR and TN borders.
Montana: Brandenberg; 91.5 F (33.1 C) in July. Located in the southeastern part of the state.
Nebraska: Beaver City; 93.3 F (33.9 C) in July. Located in the far south-central of the state near the KS border.
Nevada: Laughlin; 108.4 F (42.4 C) in July. Located on the southern tip of the state near the AZ and CA borders.
New Hampshire: Durham; 83.2 F (28.4 C) in July. Southeastern part of the state near the ME border.
New Jersey: Woodstown; 88.1 F (31.2 C) in July. Southwestern part of the state near the DE border. Close to where
snj90 lives I believe.
New Mexico: Lordsburg 4 SE; 98.1 F (36.7 C) in July. Far southwest part of the state close to the AZ border.
New York: Scarsdale; 86.0 F (30.0 C) in July. Located in the far southern part of the state near NYC and the CT border.
North Carolina: Whiteville 7 NW; 92.6 F (33.7 C) in July. Located in the inland part of the SE NC, near the SC border.
North Dakota: Medora; 86.2 F (30.1 C) in July. Located in the west-central part of the state near the MT border.
Ohio: Fairfield; 88.1 F (31.2 C) in July. Located in SW Ohio between Cincinnati and Dayton.
Oklahoma: Chattanooga; 98.6 F (37.0 C) in July. Located in the far southwest part of the state near the TX border.
Oregon: Pelton Dam; 95.4 F (35.2 C) in July. Located in the north-central part of the state east of the Cascades.
Pennsylvania: Hanover; 87.6 F (30.9 C) in July. Located in the southeastern part of the state near the MD border.
Rhode Island: Providence; 82.6 F (28.1 C) in July. This is a well-known city.
South Carolina: Columbia (Univ. of SC); 95.2 F (35.1 C) in July. Located right in the middle of the state.
South Dakota: Fort Pierre 17 WSW; 91.9 F (33.3 C) in July. Located right in the middle of the state.
Tennessee: Memphis; 92.1 F (33.4 C) in July. This is a well-known city.
Texas: Castolon; 103.4 F (39.7 C) in July. Located in the extreme SW part of the state on the Mexican border.
Utah: St. George; 102.8 F (39.3 C) in July. Located in the extreme SW part of the state near the AZ and NV borders.
Vermont: Vernon; 83.8 F (28.8 C) in July. Located on the SE corner of the state near the MA and NH borders.
Virginia: Stony Creek; 91.1 F (32.8 C) in July. Located inland in SE Virginia south of Richmond.
Washington: Smyrna; 91.0 F (32.8 C) in July. Located in the south-central part of the state.
West Virginia: Williamson; 89.4 F (31.9 C) in July. Located in the far SW part of the state near the KY border.
Wisconsin: Lake Geneva; 85.6 F (29.8 C) in July. Located inland in SE Wisconsin near the IL border.
Wyoming: Whalen; 90.7 F (32.6 C) in July. Located in the southeastern part of the state near the NE border.
Keep in mind these are 1971-2000 values.
Lived:
Residence: