Updated October 2026
Best Time to Visit Fort Union Trading Post National Historic Site
National Historic SiteMontana, North Dakota
Best month to visit
September
75°F / 46°F avg high / low
Our recommendation
Visit Fort Union Trading Post in September
September offers the lightest crowds of the park's good-weather months. For comparison, June is the most crowded month (~3.6× the average month) and January is the quietest.
- Annual visits
- 12K
- 2024
- Busiest month
- Jun
- 3.6× avg
- Quietest month
- Jan
- 0.1× avg
- 10-yr trend
- falling
- -23.2%
More photos of Fort Union Trading Post
Photos courtesy of the National Park Service (public domain).
How crowded is Fort Union Trading Post by month?
Relative crowd level by month (1.0 = the park's average month), from NPS visitation records 1979–2025.
Month-by-month crowd, weather & daylight
Fort Union Trading Post National Historic Site weather by month →
| Month | Crowd level | Best-time score | Avg high / low | Daylight |
|---|---|---|---|---|
| January | Very quiet | 1 Poor | 24°F / 4°F | 8.6 h |
| February | Very quiet | 4 Poor | 29°F / 8°F | 10.0 h |
| March | Very quiet | 7 Poor | 42°F / 19°F | 11.6 h |
| April | Very quiet | 61 Good | 58°F / 31°F | 13.4 h |
| May | Busy | 68 Good | 69°F / 42°F | 15.0 h |
| June | Very busy | 52 Fair | 77°F / 51°F | 15.8 h |
| July | Very busy | 69 Good | 85°F / 57°F | 15.5 h |
| August | Very busy | 72 Good | 85°F / 55°F | 14.1 h |
| Septemberour pick | Busy | 70 Good | 75°F / 46°F | 12.3 h |
| October | Quiet | 55 Fair | 58°F / 33°F | 10.6 h |
| November | Very quiet | 2 Poor | 40°F / 20°F | 9.0 h |
| December | Very quiet | 0 Poor | 27°F / 9°F | 8.2 h |
Climate normals (1991–2020) from the nearest NOAA station (USC00329430, ~16.8 mi away).
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About visiting Fort Union Trading Post
Fort Union Trading Post National Historic Site is a National Historic Site in MT, ND and one of the system's hidden, low-traffic units, drawing about 12,000 recreation visits in 2024. Visitation has eased over the past decade, down about 23.2%. Crowds concentrate sharply by season: June is the busiest month at about 3.6× the park's average month, while January is the calmest at roughly 0.1× — a 36-to-1 swing between high and low season. Roughly 65% of the year's visitors arrive in the three summer months of June, July and August alone, so timing a trip outside that window is the single biggest lever on how crowded the park feels. Weather swings from an average high-season warmth near 71°F in July down to about 14°F in January, with the wettest stretch in June and meaningful snowfall around December. About 5 months a year see comfortable average temperatures in the 50–80°F range, which is part of why crowd timing and weather timing don't always line up. The sweet spot is September: the lightest crowds of the park's good-weather months. Visit then and you trade a little peak-season certainty for noticeably shorter lines and easier parking than the June rush. Daylight ranges from about 8.2 hours in midwinter to 15.8 hours near the summer solstice, which shapes how much ground you can cover in a day. These crowd figures are drawn from 1979–2025 of National Park Service visitor-use records, paired with 1991–2020 NOAA climate normals, and are updated as new monthly data is released.
Park overview
Between 1828 and 1867, Fort Union was the most important fur trade post on the Upper Missouri River. Here, the Assiniboine and six other Northern Plains Tribes exchanged buffalo robes and smaller furs for goods from around the world, including cloth, guns, blankets, and beads. A bastion of peaceful coexistence, the post annually traded over 25,000 buffalo robes and $100,000 in merchandise.
Weather & conditions
Weather in western North Dakota can be harsh, with extremes in temperature and sudden, violent storms. Be prepared for rapidly changing conditions. Summers are warm with average high temperatures in the 80s-90s May through September. Winters are cold with average lows in the single digits December through February. Wind is considerable year-round. Conditions can change quickly. Travelers should be aware of the potential for violent thunderstorms in the summer and the possibility of blizzards.
Park overview text courtesy of the National Park Service — official park site.
Where to stay near Fort Union Trading Post
Hotels, cabins, lodges and vacation rentals near Fort Union Trading Post National Historic Site — live availability and prices to plan your trip. September is our pick for the best balance of light crowds and good weather. Full lodging guide: when to book, gateway vs in-park, and the crowd calendar that drives room rates.
Top-rated places to stay near Fort Union Trading Post
Prices for Oct 30–Nov 1, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
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Getting to Fort Union Trading Post
The nearest airport is Dickinson Regional Airport (DIK), about 135 mi (2 hr 40 min drive) away. Most visitors reach Fort Union Trading Post by car.
Frequently Asked Questions
September offers the lightest crowds of the park's good-weather months at Fort Union Trading Post National Historic Site. The park is busiest in June (about 3.6× the average month) and quietest in January.
June is the busiest month at Fort Union Trading Post National Historic Site, running roughly 3.6 times the park's average monthly visitation.
January is the quietest month at Fort Union Trading Post National Historic Site, at about 0.1× the average month — a good choice if you want to avoid crowds.
Fort Union Trading Post National Historic Site recorded about 12,028 recreation visits in 2024. Visitation has been falling over the past decade (-23.2%).
Based on 1991–2020 climate normals, the warmest month at Fort Union Trading Post National Historic Site averages about 71°F (July). See the month-by-month table above for the full picture.
Dickinson Regional Airport (DIK) is the closest airport to Fort Union Trading Post National Historic Site, about 135 mi (2 hr 40 min drive) away.
Nearby parks to visit
Keep exploring
Water quality of lakes near Fort Union Trading Post
If you are planning to swim, paddle or fish on this trip, these graded lakes are within a 40-mile drive. Grades are A–F from EPA and state-agency sampling.
- Arnegard Dam Lake water qualityGrade C · 28 mi · ND
- Blacktail Dam Lake water qualityGrade C · 33 mi · ND
- Epping-Springbrook Dam-Deepest Lake water qualityGrade D · 33 mi · ND
- Trenton Lake water qualityGrade — · 10 mi · ND
- Vaux Reservoir Number Two water qualityGrade — · 21 mi · MT
Sources: National Park Service Visitor Use Statistics (1979–2025), NOAA NCEI U.S. Climate Normals 1991–2020. Crowd index = a month's visits ÷ the park's average month.