Peoria has a classic Midwest continental climate with four distinct seasons. Spring (April to June) and autumn (September to October) are the most pleasant times to visit: temperatures are comfortable, the trees along Grandview Drive are at their best, and the city is not yet in the grip of summer heat or winter cold. Summers are hot and humid, with temperatures regularly in the upper 30s Celsius (90s Fahrenheit) and occasional heat spikes; winters are cold, with significant snowfall and temperatures that drop well below freezing.
The Illinois State Fair runs in Springfield, an hour south, in late August, and is worth combining with a Peoria visit if you want a taste of quintessential Midwest summer. The Peoria area hosts several river festivals and outdoor music events in summer. The fall foliage along Grandview Drive and in the river bluffs peaks in mid-to-late October and is genuinely scenic.