Seasons Yellowstone Treasures: Home / Seasons When’s a good time to visit Yellowstone? The answer depends on the activities you like and the weather you are prepared to experience. Spring Summer Autumn Winter Months: May, June Daytime: 50s & 60s °F (teens °C) Nighttime: 30s °F (0-4°C)Months: July, August Daytime: 70s – low 80s °F (20s °C) Nighttime: 40s °F or below (below 9°C)Months: September to early October Daytime: 40s – 60s °F (5-20°C) Nighttime: freezing and belowMonths: mid-October to April Daytime: around freezing to well below Nighttime: usually freezing, often below 0°F (-18°C) Pros Baby animals numerous Wildflowers at lower elevations Waterfalls at their peak Pros Wildflowers everywhere Drier trails Berries ripening in August Clear, starlit nights Great fishing Pros Cool but pleasant Fewer visitors Great light for photography Elk gathering in herds and bugling Aspen turn golden Pros Cross-country skiing Ice-encrusted “ghost” trees Animals gather near roads Snowmobiling Cons Some mountain passes closed Biting insects common Meadows flooded, streams very high Cons Peak numbers of visitors Late afternoon thunderstorms Potential fires or hordes of grasshoppers in dry years Cons Cold nights Greater chance of rain & snow All campgrounds but Mammoth Campground close Cons Extreme cold Heavy snows and severe storms Most roads are closed to cars Updated August 23, 2017. Copyright Janet Chapple. All rights reserved.