The October 28 forecast for Mammoth in northern Yellowstone called for a high of 38°F and a low of 26°F. RV travelers planning a visit through the weekend needed to account for both the cold and the October 31 seasonal closing date listed for major roads. Weekend rain and snow chances meant clear Wednesday conditions could not be assumed for later plans.
Areas Affected
NWS updated its forecast for Mammoth, at 5,745 feet, at 5:47 a.m. MDT October 28. It called for mostly sunny daytime skies and south-southwest winds of 9–13 mph, then partly cloudy conditions with an overnight low below freezing. October 29 was forecast at 45°F by day and 31°F at night.
Conditions could change from the night of October 30. The forecast gave Friday night a 30% precipitation chance and Saturday 70%, with mixed rain and snow possibly changing to rain after noon. This was a point forecast for Mammoth, not a confirmation of snowfall or road closures throughout the park. Higher passes and southern areas required their own forecasts.
NPS’s 2026 road schedule listed October 31 as the closing date for major sections including Mammoth–Norris, Norris–Canyon and Madison–Old Faithful. The basic winter connection open to ordinary vehicles runs from the North Entrance at Gardiner through Tower Junction to the Northeast Entrance at Cooke City. Beartooth Highway was already listed as seasonally closed, so roads beyond the northeastern exit needed separate review.
What RV Travelers Need to Know
Year-round Mammoth Campground lists October 15–April 1 as its first-come, first-served period. The NPS winter table limits RV and vehicle combinations to 30 feet, with no electric or water hookups. Daytime arrival does not guarantee a site. Check total vehicle length, heat and water preparations, and have alternative lodging in mind.
Summer reservation experience should not be applied unchanged. The NPS schedule listed Madison and Fishing Bridge RV Park as closing October 17, 2026. After full-hookup Fishing Bridge closed, travelers could not plan on finding an equivalent site inside the park. NPS also noted that dump stations may close as temperatures fall.
Travelers from Mammoth toward Tower Junction also needed to consider Gardner River High Bridge construction. NPS described one-lane traffic and delays up to 15 minutes through late October. On the departure date, consult current park conditions and road information at 307-344-2117 for actual access. Weather closures can precede scheduled seasonal closing dates.
Sources: NWS Mammoth forecast · NPS 2026 road schedule · NPS campground operating table · Mammoth Campground
Photo: NPS / Neal Herbert · Original photo · Photographed October 10, 2014 · Public domain