Here's a comparison between Fresno and Las Vegas weather.
Fresno is dark in December and early January, but you can be wearing shorts by mid January a lot of years.
https://weatherspark.com/compare/y/2...gas-and-Fresno
Link compares both cities
Fresno is less humid and not as hot as Vegas is in the summer. I think Vegas hit 114f+ heat index this year, while Fresno topped at about 106-107 heat index.
If you're going to consider Vegas, also consider inland CA(sac to fresno and IE areas)