September in Yosemite National Park is a good month: highs around 84°F, lows around 51°F. Crowds: busy — #4 busiest of the park's 12 months. Warm, calmer valley — climbers' season on El Cap. The editorial best window here is May–June. You get about 12h 25m of daylight. To finish Half Dome (7h 45m) before dark, leave the trailhead by about 11:21 AM.
Month data reviewed · how we check this
| Verdict | Good A solid visit with a caveat — usually crowds or heat. |
|---|---|
| Temps °F | 84° high / 51° low |
| Crowds | busy · #4 busiest of the park's 12 months |
| What September is like | Warm, calmer valley — climbers' season on El Cap |
| Best window (whole year) | May–June |
| Peak crowds (whole year) | Jun–Aug |
CROWDS: RELATIVE SEASONALITY FROM NPS VISITATION STATISTICS · TEMPS: APPROXIMATE NOAA NORMALS AT MAIN VISITOR ELEVATION — HIGH COUNTRY RUNS 10–20°F COLDER
DAYLIGHT ON SEPTEMBER 15 · LOCAL PARK TIME (PDT)COMPUTED FROM THE PARK'S OWN COORDINATES FOR THE 15TH — THE MIDDLE OF THE MONTH STANDS FOR IT, AS IT DOES FOR CLIMATE NORMALS. WITHIN A MONTH THESE TIMES SHIFT BY UP TO AN HOUR
LEAVE THE TRAILHEAD BY — TO FINISH BEFORE DARK ON SEPTEMBER 15WALKING TIMES ESTIMATED FROM EACH TRAIL'S MEASURED DISTANCE AND ELEVATION GAIN — A PLANNING FIGURE, NOT A PACE. ADD YOUR OWN MARGIN FOR PHOTOS, REST AND CROWDS. WATER AT THE COOL-WEATHER RATE, BECAUSE THIS MONTH AVERAGES 84°F. TRAILS WE HAVE NOT MEASURED ARE LEFT OUT RATHER THAN GUESSED
WHAT SEPTEMBER ASKS OF YOU HEREYosemite National Park in October — Good, highs around 72°F, crowds: moderate (golden light and thin crowds).
Our verdict for September is "Good". A solid visit with a caveat — usually crowds or heat. Expect highs around 84°F and lows around 51°F, with crowds at the "busy" 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 May–June, and the peak-crowd months are Jun–Aug. September itself we rate "Good".
About 12h 25m on September 15: the sun rises around 6:40 AM and sets around 7:05 PM local park time (PDT). Computed from the park's own coordinates, so it is the light you actually get at the trailhead, not the nearest city's.
Half Dome takes about 7h 45m of walking, so on September 15 you would need to leave the trailhead by about 11:21 AM to finish before dark — the sun sets around 7:05 PM local park time (PDT). Walking times are estimated from each trail's measured distance and elevation gain, so treat them as a planning figure and add your own margin for photos, rest and crowds.
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