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WhenToVisitParks

Fort Union National Monument in September

Busy1.2× average month · best-time score 57/100

September at Fort Union National Monument averages a daytime high near 80°F and an overnight low around 43°F, with about 2.1" of precipitation. Visitation runs about 1.2× the park's average month, which makes September a busy month here.

Average low
43°F
Average high
80°F

Range across the year: 14°F to 88°F

Crowds
1.2× averageBusy
  1. J
  2. F
  3. M
  4. A
  5. M
  6. J
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  8. A
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Precipitation
2.1 in
Daylight
12.2 hours

Roughly 10% of the park's yearly visitors come in September: roughly 1,000 recreation visits in a typical year, based on National Park Service monthly counts from 1979 to 2025.

That makes September the 5th-busiest of the park's twelve months, sitting between the June peak (1.7×) and the January low (0.3×).

On our Best Time to Visit score September rates 57/100 ("Fair"). Our recommended month is October: the lightest crowds of the park's good-weather months.

The daily average of about 62°F is a comfortable range for hiking and being outdoors all day. These figures are 1991–2020 NOAA climate normals from the nearest station, about 8 miles from the park.

Because June, July and August together draw about 37% of annual visitors, choosing September instead steps outside that summer crush — the single biggest lever on how crowded the park feels.

You'll have about 12.2 hours of daylight in September to explore — between the 9.6-hour midwinter low and the 14.4-hour summer high.

Park-wide, 2024 drew 9,217 recreation visits, down 3.7% from 9,570 in 2023.

Across the past decade overall visitation has eased about 12.5%, so September may feel a touch quieter than it once did.

How September compares with the months around it

MonthAvg high / lowCrowdsBest-time score
August85°F / 51°F1.2× Busy64 Good
September80°F / 43°F1.2× Busy57 Fair
October71°F / 32°F1.1× Average46 Fair

All twelve months at Fort Union, with the best time to visit.

Reviewed by WhenToVisitParks Editorial Team · Updated

Frequently Asked Questions

September averages a daytime high near 80°F and an overnight low around 43°F at Fort Union National Monument, with about 2.1 inches of precipitation. These are 1991–2020 NOAA climate normals from the nearest station, about 8 miles from the park, so conditions inside the park can differ, especially at other elevations.

September is busy at Fort Union National Monument (about 1.2× the average month). Our best-time score rates it "Fair" at 57/100. Our recommended month is October.

The busiest month is June and the quietest is January. September sits at about 1.2× the park's average, or 10% of annual visitation.

A typical September sees about 1,000 recreation visits at Fort Union National Monument, based on National Park Service monthly counts from 1979–2025.

Where to stay near Fort Union in September

Booking a September trip to Fort Union National Monument? Compare hotels, cabins and vacation rentals near the park with live September availability and prices.

Top-rated places to stay near Fort Union

Prices for Oct 30–Nov 1, 4 adults. Change dates on the map below.

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See the full ranking of the best national parks to visit in September.

Source: National Park Service Visitor Use Statistics (1979–2025), NOAA NCEI Climate Normals 1991–2020. Updated 2026-10-11.