When to Go
The Heartland has a superb climate—rarely does it get overly hot or cold, although winter evenings can get nippy, especially in northern Zacatecas. The hottest time of year is the end of the dry season, in April and May.
Average temperatures in Morelia range from 20°C (68°F) in May to just under 13°C (55°F) in January. Zacatecas is more extreme, with winter temperatures as low as 0°C (32°F) and snow flurries every several years, and summer highs of 28°C–30°C (81°F–85°F). Expect cool nights year-round in most of the region's cities.
The Heartland's rainy season hits between June and October and is strongest in July and August. At this time, the semiarid countryside comes to life with pink, yellow, and blue wildflowers, and the farms offer up fresh vegetables and fruits.
The good news is that for the most part, high season is limited to Christmas, Easter, and the weeks around regional festivals. San Miguel bustles with weekend visitors from Querétaro and Mexico City year-round, but is at its busiest in September, when it honors Mexican independence during the first two weeks of the month and celebrates St. Michael, its patron saint, during the latter two weeks. Tourism also spikes around the Day of the Dead celebrations in Pátzcuaro, November 1–2; during Morelia's International Organ Festival in May; and during Guanajuato's International Cervantes Festival in October.