September in Arches National Park is a best window month: highs around 88°F, lows around 55°F. Crowds: peak crowds — #1 busiest of the park's 12 months. The sweet spot returns; Labor Day weekend is a peak. The editorial best window here is April–May & September–October. You get about 12h 26m of daylight. To finish Devils Garden Trail (full loop) (2h 45m) before dark, leave the trailhead by about 4:39 PM.
Month data reviewed · how we check this
| Verdict | Best window The editorial pick — weather, access and experience line up. |
|---|---|
| Temps °F | 88° high / 55° low |
| Crowds | peak crowds · #1 busiest of the park's 12 months |
| What September is like | The sweet spot returns; Labor Day weekend is a peak |
| Best window (whole year) | April–May & September–October |
| Peak crowds (whole year) | Apr–May, Sep–Oct |
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 (MDT)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 HOT-WEATHER RATE, BECAUSE THIS MONTH AVERAGES 88°F. TRAILS WE HAVE NOT MEASURED ARE LEFT OUT RATHER THAN GUESSED
WHAT SEPTEMBER ASKS OF YOU HEREArches National Park in October — Best window, highs around 74°F, crowds: peak crowds (warm days, cold nights, the last busy month of the year).
Our verdict for September is "Best window". The editorial pick — weather, access and experience line up. Expect highs around 88°F and lows around 55°F, with crowds at the "peak crowds" 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 April–May & September–October, and the peak-crowd months are Apr–May, Sep–Oct. September itself we rate "Best window".
About 12h 26m on September 15: the sun rises around 7:00 AM and sets around 7:26 PM local park time (MDT). Computed from the park's own coordinates, so it is the light you actually get at the trailhead, not the nearest city's.
Devils Garden Trail (full loop) takes about 2h 45m of walking, so on September 15 you would need to leave the trailhead by about 4:39 PM to finish before dark — the sun sets around 7:26 PM local park time (MDT). 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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