With daytime temperatures of 17°C (63°F) and nighttime lows of 0°C (32°F), September in Yellowstone National Park brings moderate temperatures during the day. Some rainfall is to be expected during the month.
Should you favor a climate that's both dry and comfortably warm, July and August typically offer the most agreeable circumstances. If you're seeking pleasant, dry and sunny weather somewhere else in the world, our weather planner can help you explore other options.
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Pick a month to see the average temperature, rainfall and sunshine in Yellowstone National Park - and find the best time to visit.
45-year average (1976-2025)
Based on our historical records, temperatures in Yellowstone National Park typically drop from around 20°C (68°F) at the start of September to approximately 14°C (57°F) by the end. Nights are cold, with lows typically ranging from -2°C (28°F) to 3°C (37°F).
45-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Browse day-by-day weather records for Yellowstone National Park spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Our historical data for Yellowstone National Park spans 2001 to 2026, revealing these weather extremes.
Find out more about the weather in the United States of America and which places have the best travel conditions in this month. See all of the United States of America in September →
Perfect weather is subjective. On this map perfect weather has been defined with temperatures between 20°C (68°F) and 29°C (84°F) and not too much precipitation (less than 90 mm (3.5 in) a month).
Comfortable temperatures call for an easy wardrobe in September. Pack summer basics like t-shirts and shorts, but include a light jacket for cooler moments. A pair of comfortable walking shoes is essential. Wet weather is likely, so pack waterproof gear for multiple rainy days.
We rated the following activities from 1 (least suitable) to 10 (best) to do.
See the full Yellowstone National Park climate overview or explore weather in the United States of America.
Where to go in September - average daytime high across popular destinations.
Need travel inspiration? Check out our bucket list articles and be inspired.
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