Why is northern Mexico hotter than southern Mexico? It would seem that the south would be warmer because it is closer to the equator. But that is not the case! Why is that?
Well, it isn’t exactly true, year-round.
According to this map Mexico in January is warmer to the South, with a slightly cooler line running down the “spine” of the region where the mountains are.
And according to this map Mexico in July follows the same basic trend, with the significant exception that the deserts in Sonora, Chihuahua, and surrounding the Gulf of California are much hotter. I would guess that the lack of seasons and the tropical foliage on the Yucatan tend to keep the temperatures stable, while the sun-absorbing stone of the desert heats up in the summer but fails to heat up in the winter.±-----------
Sorry, I hit Submit while correcting the post. The desert references should have been:
“deserts in Coahuila (right under Texas), Chihuahua, and Sonora and surrounding the Gulf of California”
Note also that, according to both maps, the north has the greater temperature range, which is to be expected as you move north of the tropics into a drier climate.