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WhenToVisitParks

Methodology

Reviewed by WhenToVisitParks Editorial Team · Updated

WhenToVisitParks answers one question for every U.S. national park unit: when should you actually go? We do it with public data only — no opinions, no sponsored placements — and we publish exactly how the numbers are built so you can judge them yourself.

Data sources

The crowd index

For each park we average the last ten full years of monthly visits to get a typical seasonal curve, then express each month as a crowd index: the month's visits divided by the park's average month. A value of 1.0 is an average month, 0.5 means half as busy as usual, and 2.0 means twice as busy. Because the index is relative to each park's own baseline, it is comparable across a tiny monument and a marquee park alike.

The Best Time to Visit Score

Each month gets a 0–100 score combining three transparent, fixed-weight components:

  • Crowd avoidance (40%) — quieter months score higher, measured across the months a park is actually visited. A month that draws under a fifth of the park's average visits earns nothing here.
  • Weather comfort (45%) — average temperatures near a comfortable ~68°F score highest, with penalties for heavy rain, for snow, and for average highs above 85°F.
  • Daylight (15%) — longer days score higher.

How the recommended month is chosen

The headline recommendation is deliberately not the warmest month, because the warmest month is usually the most crowded. We look for the shoulder season first: a month with pleasant weather, an average high no hotter than 86°F, and crowds at or below the park's median month. Of the months that qualify, we pick the least crowded.

Many mountain and northern parks have no such month, because every pleasant month is also a busy one. For those parks we take the months whose weather comes close to the best that park gets, and pick the least crowded of them. At Yellowstone that is September rather than July.

Two guards apply to every pick:

  • Not a month almost nobody visits. A month that draws less than a fifth of the park's average monthly visits is never recommended. Visitation that low usually reflects closed roads, closed facilities, or weather most people avoid, and a visit count cannot tell us which.
  • Not a hot month. A month whose average high tops 86°F is not recommended while a cooler month with good weather exists.

The recommended month is not always the month with the highest score. The score trades crowds, weather and daylight off against each other, so at a park with a short season a cold, quiet month can out-score a mild, busier one. The recommendation asks for good weather first and thin crowds second.

The recommended month is a planning signal, not a promise of access. Seasonal road and facility closures are set by each park and change from year to year, so check the park's current conditions before you book.

Coverage and known limitations

  • We cover 385 NPS units — not just the famous 63 "National Parks." Every one is matched to a NOAA station that publishes temperature normals.
  • NPS counts "recreation visits," which approximate but do not exactly equal unique people.
  • Crowd patterns describe a typical year. A specific holiday weekend, eclipse, or event can run far busier than the monthly average.
  • Climate figures come from one station near the park, not from inside it. For 348 of 385 parks that station is within 15 miles; for 6 remote units, mostly in Alaska, it is more than 50 miles away (112 miles at the farthest), so read those figures as regional. A station at a different elevation, or inland from a coastal park, can run 10°F or more away from what you will find on the trail. Each park page names its station and the distance.

Updates

Crowd data refreshes annually when the NPS publishes the prior year's monthly figures; climate normals update on NOAA's decadal cycle. This page and every park page show their last-updated date. Data current as of 2026-10-11.