When to hike the JMT — season, snow and weather

The John Muir Trail has a short, weather-defined season, and it is worth being precise about which edge of it you mean. The usual season — the window this site plans against — is July to September. Inside that, the stretch that is comfortable for most people is mid-July to mid-September. Outside it, the trail is often walkable from early July until the first real snow, usually in October⁠iYosemite National Park, Seasonsread 2 October 2026In most years, most trails except those at the highest elevations typically have little or no snow by early July and this remains the case until we get our first significant snow, which is typically sometime in October.nps.govPacific Crest Trail Association, JMT FAQread 2 October 2026Most years one can plan a trip beginning the first week in July, and only hike on snow near the tops of the passes. The first substantial snow usually comes sometime in October.pcta.orgBoth sources put the opening about a week later than the late June this article used to give. A low-snow year can open earlier; no agency gives a date for that., on conditions rather than on the calendar. A low-snow winter can open it in late June. The exact edges move by weeks depending on one number: the previous winter’s snowpack.

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WalkableOften walkable, from early July to the start of October. Both dates are approximate.

ComfortableComfortable for most, from mid July to mid September. Both dates are approximate.

Snow and fordsSnow on the passes and high fords, from the start of the chart in January to late June. It continues beyond the chart at the January end. The end date is approximate.

MosquitoesMosquitoes, from the start of July to early August. Both dates are approximate.

StormsAfternoon thunderstorms, from mid July to late August. Both dates are approximate.

BusiestBusiest, from the start of August to the end of August. Both dates are approximate.

Autumn stormsFirst autumn storms, from the start of September to the end of the chart in December. It continues beyond the chart at the December end. The start date is approximate.

Snowpack sets the start

The passes are what close the trail, not the valleys. Forester Pass at 13,200 feet, Muir Pass at 11,955 feet and Mather Pass at about 12,100 feet all hold snow on their north-facing approaches long after the trail below is dry. In a low-snow year the route can be effectively clear by late June. After a winter at 150 percent of average, dangerous creek crossings and firm snow on the passes can persist into late July⁠iSequoia & Kings Canyon National Parks, Rae Lakes Loopread 2 October 2026Glen Pass may be impassable to hikers until mid-late July and even later for stock.nps.govYosemite National Park, Seasonsread 2 October 2026Depending on the winter's snowpack, access to higher elevations may be limited until July or even later.nps.gov.

Check the April 1 snow-water-equivalent figures for the southern Sierra before you commit to a June or early-July start. If they are well above average, plan for an ice axe, traction, real snow-travel skill, and fords that are genuinely hazardous rather than merely cold.

Month by month

June. Long days and empty trail, but the highest risk. Creek crossings are at peak flow⁠iSequoia & Kings Canyon National Parks, River Safetyread 2 October 2026The most dangerous times are during spring and early summer when melting snow from the mountains makes river waters swift, icy cold, and extremely hazardous.nps.govYosemite National Park, Visiting in Summerread 2 October 2026Peak runoff typically occurs in May or Junenps.gov — Bear Creek, Mono Creek, Evolution Creek and the Whitney-side drainages have all injured or killed people at high water. Snow travel on the passes is likely. Mosquitoes are ramping up.

July. The mosquitoes peak in the first half of the month around lakes and meadows, and they are not a minor annoyance; head nets earn their weight. Fords drop steadily. From roughly mid-July the North American monsoon starts pushing moisture north, so afternoon thunderstorms become a daily planning constraint. Days are warm, nights are usually just above freezing.

August. For most people the best compromise. Snow is gone from all but the shadiest aspects, fords are manageable, and the mosquitoes, generally prevalent in July and early August⁠iInyo National Forest, Wilderness Safetyread 2 October 2026Protect yourself against sunburn and early season mosquitoes, generally prevalent in July and early August.fs.usda.govThe sentence sits inside the collapsed Weather panel; open it to read it. Before this source the article had mosquitoes fading after mid-August., thin out as the month goes on. Thunderstorms are still common in the afternoon. This is also when the trail is busiest⁠iSequoia and Kings Canyon Wilderness Stewardship Plan / FEIS, Appendix A (PDF)read 2 October 2026The busiest month of the year, August, alone accounts for one-third of the year’s total.parkplanning.nps.govFrom 2010–2012 permit data, and it excludes JMT hikers who start in Yosemite. Recreation.gov reservations for 2024 and 2025 agree for Inyo, SEKI and Sierra NF; at Yosemite July and August are about equal, and the busiest days are Labor Day weekend (docs/reviews/2026-10-02/season-sources).: late July is nearly as crowded, and the rush runs through Labor Day weekend into early September.

September. Arguably the best trail conditions of the year: afternoon storms thin out, no bugs, clear light, low water. The trade is cold. Nights at 10,000 to 11,000 feet regularly drop into the 20s Fahrenheit and can reach the teens late in the month. Daylight shrinks fast. The first real Pacific storm can arrive as early as September⁠iYosemite National Park, Seasonsread 2 October 2026At higher elevations, snow may fall as early as September or October.nps.govInyo National Forest, Mount Whitneyread 2 October 2026The trail is usually snow-free from July to late Septemberfs.usda.gov, and it can drop snow on the passes overnight.

October. Occasionally glorious, frequently over. Resupply points close, days are short and cold, and a single storm can end the trip.

Daily weather rhythm

Between mid-July and late August the pattern is reliable enough to plan around: clear mornings, building cumulus by late morning, thunderstorms between roughly 1pm and 5pm, clearing in the evening. Monsoon storms can continue through September⁠iYosemite National Park, Lightning Safetyread 2 October 2026During July through September, the North American monsoonal weather pattern can cause moisture from the Gulf of California to flow into the Sierra Nevada, resulting in thunderstorms.nps.govDevils Postpile National Monument, Weatherread 2 October 2026Afternoon thunderstorms are possible in July and August.nps.govDevils Postpile names July and August; Yosemite names July through September. The article keeps mid-July to late August as the reliable pattern and says storms can continue through September., less predictably. The practical rule is to be over your pass and off exposed ground before early afternoon. That means starting at first light on pass days, which also gets you firmer snow in early season and softer light for the walk.

Firmer is not always safer. In a snowy early season, snow that softens during the day refreezes overnight⁠iAndrew Skurkaread 2 October 2026the snow to firm up or crust over. This can make even low-angle snow problematic for early-risers and dawn-to-dusk hikers.andrewskurka.com, and on steep, shaded north-facing slopes it can be hard ice at first light. Mather Pass is the case hikers write about: its north side, above Palisade Lakes, can be a steep ice chute in the early morning⁠iHalfway Anywhereread 2 October 2026If you decide to cross Mather Pass in the early morning, you can expect the northern side to be a steep ice chute.halfwayanywhere.comHalfway Anywhereread 2 October 2026To the north of Mather Pass is the Palisade Basin – home to Palisade Lakeshalfwayanywhere.com. Check the Sequoia and Kings Canyon trail conditions page, which reports passes by name⁠iNPS Sequoia & Kings Canyonread 2 October 2026Mather Pass 09/01/2026 - Clear and stock passable.nps.gov, before a snowy-year pass day. If the passes still hold snow, carry traction and an ice axe, and know how to use them before you need them.

Temperatures to plan for

Most nights are spent between 9,000 and 11,500 feet, so the numbers that matter are alpine numbers, not valley ones. Expect daytime highs of roughly 60 to 75°F and overnight lows of 25 to 40°F through the core season, colder in September. A 20°F sleeping bag is the common choice; a 30°F bag works in August for people who sleep warm.

Smoke is now part of the calculation

Late summer and autumn are peak wildfire season in California. Smoke from fires hundreds of miles away can sit in the Sierra for days, and closures can appear with very little notice. Check air quality and active incidents in the days before you start, and again at every resupply where you get signal.