Crowd score
Formula: 100 − (this month's visits ÷ park's peak month visits) × 100. Each park scored against its own peak, not against other parks.
Source: NPS Visitor Use Statistics Data Package 2025, Recreation Visits (TRV), 5-year monthly mean (2021-2025). Reproduce these numbers on the NPS IRMA Stats portal.
Reading it: July at Mount Rainier reads 0 (peak). November reads 93 (nearly empty). A 50 means about half the park's peak crowd.
Weather score
Formula: weatherScore = round(max(0, min(100, dayComfort − precipPenalty − snowPenalty − freezePenalty))). The piecewise day-comfort function is continuous at every boundary.
- Day comfort:
tmax < 50°F →
max(10, (tmax − 20) × 2) (cold tail);
50–60°F → 60 + (tmax − 50) × 4 (ramp to 100);
60–78°F → 100 (plateau);
78–85°F → 100 − (tmax − 78) × 5 (ramp to 65);
> 85°F → max(30, 65 − (tmax − 85) × 5) (hot tail).
- Precip penalty:
max(0, prcpIn − 1.5) × 8; kicks in above 1.5 in / month.
- Snow penalty:
snowIn × 2.5.
- Night-freeze penalty:
max(0, 32 − tmin) × 1.5 when tmin < 32°F.
Source: NOAA NCEI U.S. Climate Normals 1991-2020, station Longmire Rainier NPS, WA (USC00454764, 2,762 ft).
Caveat: The Longmire NPS cooperative observer station sits inside the park at ~2,762 ft, on the year-round Nisqually-Paradise corridor near the Longmire museum and the National Park Inn. It is the best NOAA monthly-normals match for the visitor corridor where most road-based activity actually happens. Mount Rainier's elevations span sea-level entrance corridors to the 14,411-ft summit; the alpine destinations the page calls out: Paradise (~5,400 ft) and Sunrise (~6,400 ft), run 10-15°F colder than Longmire year-round and absorb roughly twice the snowfall. Paradise is one of the snowiest places on Earth where snowfall is regularly measured per NPS. Camp Muir at 10,080 ft and the summit at 14,411 ft sit in a different climate regime entirely. Treat these Longmire numbers as a gateway-corridor proxy; alpine planning at Paradise, Sunrise, and Camp Muir needs a high-country forecast. PREVIEW status. The NCEI pipeline has not yet wired MORA into monthly_climate_normals.csv (only ACAD is in for now) and no manual selection row exists in weather_station_selections.csv. The five MORA candidates in noaa_station_candidates.csv span Longmire, the Paradise NPS observer (USC00456898), Paradise SNOTEL, Cayuse Pass SNOTEL, and Morse Lake SNOTEL; final selection should be approved in data/manual/weather_station_selections.csv.
Access score
Formula: For each named park road, count it open if its typical operating window covers that month. Score = round((sum of weights of open roads / sum of all weights) x 100). Where a park has a partial winter access mode, the profile documents that assumption in its access notes.
Route weights at Mount Rainier:
- Nisqually-Longmire-Paradise corridor (SR706): Year-round; winter day-use only at Paradise
- Stevens Canyon Road: Typically late May → mid-October
- Sunrise Road: Typically late June → mid-September
- Carbon River and Mowich Lake (NW corner): Vehicle access restricted: verify WSDOT bridge status
- Westside Road: Vehicle access to 3 mi only
- Timed-entry vehicle reservations: Year-variable summer window · check NPS Mount Rainier
- Entry, fees, and passes: Year-round entry
- Lodging. Paradise Inn and National Park Inn: Paradise Inn seasonal; National Park Inn year-round
- Climbing: Camp Muir and the summit: Permits required · season ~late May → early September
- Alpine safety, weather and afternoon clouds: Year-round · alpine risk peaks summer
Editorial methodology, the route weights themselves are author-curated, sourced from data/processed/operations/road_windows.csv and the park's own access caveats below the score table.
Caveat: The score reflects wheeled-vehicle road access only. Backcountry, hiking, lodging, shuttle, and other service availability are not directly included unless the park profile states otherwise.
Why no combined score?
A combined "best month" number forces a weighting: how much do you care about crowds vs. weather vs. access? Those weights are personal. A photographer optimizing for golden light weights differently than a parent locked to school break weights differently than a winter visitor with a 4WD. We show the inputs and let you decide. Use the per-month grid above to navigate to a deeper page.
