Hottest? Last summer, driving home, Dallas-Fort Worth metroplex area. The A/C in the car I was driving was busted, it had zero window tint and a plexiglas roof panel so there was no shade whatsoever. The area was getting that extremely dry late-summer heat that area gets during made worse by the heat dome effect over the city. The actual temp was likely 108°-110°F, but the "feels like" was somewhere in the upper 120°s. Add to that the fact that the wind itself was literally hot, and there I was driving down the highway with my windows down cooking in what basically amounted to a convection oven. I ended up finding that I was actually cooler if I rolled the windows up. When I got home my shirt was totally soaked and as a result, it has the shadow of a seatbelt burned into it.
Coldest? Around -20°F in central Utah during winter at about 3AM during an impromptu snowball fight in the apartment complex I lived in. Zero wind and about a foot of snow on the ground. Again, surprisingly dry, so it was legitimately PLEASANT with a ski jacket, long johns and jeans, when compared to a humid, windy winter as warm as 32°F anywhere else in the same gear, but definitely the coldest temperature I've seen by the numbers.