September in Yellowstone National Park is a best window month: highs around 66°F, lows around 36°F. Crowds: moderate — #4 busiest of the park's 12 months. Elk rut echoes through the valleys; crowds thin, mornings crisp. The editorial best window here is June & September.
| Verdict | Best window The editorial pick — weather, access and experience line up. |
|---|---|
| Temps °F | 66° high / 36° low |
| Crowds | moderate · #4 busiest of the park's 12 months |
| What September is like | Elk rut echoes through the valleys; crowds thin, mornings crisp |
| Best window (whole year) | June & September |
| Peak crowds (whole year) | Jul–Aug |
CROWDS: RELATIVE SEASONALITY FROM NPS VISITATION STATISTICS · TEMPS: APPROXIMATE NOAA NORMALS AT MAIN VISITOR ELEVATION — HIGH COUNTRY RUNS 10–20°F COLDER
Yellowstone National Park in October — Shoulder, highs around 52°F, crowds: quiet (roads begin closing for winter; snow arrives early).
Our verdict for September is "Best window". The editorial pick — weather, access and experience line up. Expect highs around 66°F and lows around 36°F, with crowds at the "moderate" level. Temperatures are approximate NOAA normals at the main visitor elevation; crowd levels follow published NPS visitation statistics.
Across the full 12-month review, the best window is June & September, and the peak-crowd months are Jul–Aug. September itself we rate "Best window".
October we rate "Shoulder" against "Best window" for September, with highs around 52°F and crowds at the "quiet" level.
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