Glacier National Park is one of America’s most iconic national parks and offers some of the most epic hiking and outdoor adventures. Whether you’re looking for the best weather or the most solitude, every season in Glacier has something to offer.
This guide takes a look at the prevailing weather patterns that impact hiking and outdoor adventures conditions in Glacier, while also taking a month-to-month and seasonal look. The guide also provides monthly weather averages for three distinct locations in the park.
Prevailing Weather Patterns
1. Moist Pacific storm systems in a westerly flow that bring heavy precipitation to areas along and west of the Continental Divide and warm and dry Chinook winds to areas east of the Divide. This pattern is common from late fall through early spring (November-March) and most pronounced when the jet stream is oriented from west to east and located near or just south of the park.
2. Slow-moving low pressure systems that are common in the spring and occasionally in the fall. In these patterns, precipitation initially falls west of the Divide ahead of the Low, before shifting to areas east of the Divide as counterclockwise (cyclonic) winds around the low pressure center shift to an easterly flow.
3. Continental or arctic cold fronts that arrive from the north, and move from north to south across the adjacent plains, leading to significant cool-downs along with light to moderate upslope precipitation falling along and east of the Continental Divide. Areas west of the Divide are typically drier in these patterns and experience less pronounced cool-downs compared to areas east of the Divide.
4. Spring and summer convective showers and thunderstorms. In these setups, instability and topographic uplift contribute to the development of showers and thunderstorms. The convective nature of these showers/storms overrides the orographic/rain shadow effect, so rainfall differences due to altitude or location east vs. west of the Divide are less pronounced. In fact, in many instances storms will develop right along the Divide before tracking east.
Wet and Dry Seasons
Annual precipitation in Glacier National Park is around 30 inches across the western border of the park, 25 inches around the eastern border of the park, and up to 70 inches along the crest of the Continental Divide above 6,000 feet.
The wet season in Glacier typically lasts from mid-October through the end of June, with the heaviest precipitation falling from November through January. The park sees an uptick in precipitation in May and June as well. The dry season in Glacier typically lasts from early July through mid-October when precipitation is lighter and less frequent.
July and August are the two driest and warmest months overall, but are also the two most crowded months in terms of visitors.
The two graphs below show the historical daily precipitation percentages over the course of the year at West Glacier (west side of the park) and St. Mary (east side of the park).
Months and Seasons
Visiting Glacier in May
May is the first month of the year when things begin to open up, ever so gradually, in Glacier after the long winter season. Most of the roads will open up by early in the month, depending on how heavy the snowpack is.
The exception, of course, is Going to the Sun Road which remains closed between the end of Lake McDonald and St. Mary. However, as crews work on plowing the road, you can access and ride your bike on the plowed portions of the road — a neat way to see areas that are normally crowded in mid-summer.
Hiking trails across the lower elevations near the eastern and western borders of the park typically dry out and become do-able in May while the higher elevations remain snowed in.
Backcountry skiers looking for some corn turns and more stable snow will find that May is a good time to access Glacier National Park, especially as road access starts to open up.
In terms of weather, expect a mixed bag. May is the second rainiest month of the year in Glacier with rain or precipitation falling on an average of 10-13 days. Snow will fall at the higher elevations periodically through the month, and occasionally can fall at the lower elevations as well.
Average high temperatures range from the 60s at the lower elevations to the 40s at the higher elevations with average low temperatures in the 20s to 30s. On the warmest days in May, high temperatures can reach the upper 70s to near 80, while on the coldest days, low temperatures fall into the 20s.
May is the 5th busiest month on average, but visitation is only 18% of the peak visitation month in July, so overall this is a quiet month.
Campgrounds begin to open up in May and facilities will gradually start to open up as well, yet many areas will still remain closed until Memorial Day or later.
Pros of visiting in May: Solitude, Improving road access compared to winter, Hiking options at lower elevations, Early enough that bug aren’t bad yet, Long days, Low elevation green-up and wildflower blooms, Biking on Going to the Sun Road, Good backcountry skiing.
Cons of visiting in May: Rain is frequent, Hiking is limited due to snow, Temperatures can be chilly, Road access to higher terrain is limited to nonexistent, Facilities and camping are limited.
Visiting Glacier in June
Snowpack continues to rapidly decline in June, which allows for more hiking options as the month progresses. Most trails up to 6,000 feet typically become do-able by mid to late month, though lingering areas of snow and areas of running water from snowmelt should still be expected.
Going to the Sun Road will gradually open up as the month progresses, but the top of the road at Logan Pass may not open to thru-traffic by the end of the month unless it has been a light snow year and/or a warm spring.
Most of the facilities and campgrounds in the park will open up during June as well, but crowds also begin to increase. June is the 3rd busiest month on average with visitation at 62% of peak.
Although temperatures are warmer in June, the weather can be challenging at this time of year. June is the last month of Glacier’s traditional wet season, but it is also the rainiest month of the year in the park with rain falling on 12-14 days on average. Thunderstorms also become more common during June compared to prior months.
The higher elevations in Glacier, including Logan Pass, will occasionally see late season snowfall events in June, but new snow melts quickly as the sun is strong at this time of year. The longest days of the year do occur in June after all.
Average high temperatures in June range from the upper 60s to low 70s at the lower elevations to the 50s at the higher elevations with average low temperatures in the 30s to 40s. On the warmest days in June, high temperatures will reach the 80s, while on the coolest days, low temperatures will fall to around freezing (and even colder up high).
Pros of visiting in June: Improving road access, Improving hiking trail access across mid-elevations, Long days, Comfortable temperatures, Vegetation is very green, Wildflowers, Most if not all campsites and facilities are open, Access to late season backcountry skiing.
Cons of visiting in June: More crowded, Bugs increase across the lower elevations, Rainiest month of the year, Higher elevations are still snowed in, Logan Pass usually remains closed through late June if not longer.
Visiting Glacier in July
July is the start of the prime season for hiking and recreating in Glacier National Park as the high elevations melt out and trail access opens up. In heavy snow years, the higher trails could still be difficult to access during the first half of the month, but typically by mid to late July, things are good to go.
Going to the Sun Road typically opens up by early July as well, which further increases access in the park. Of course, July is also the busiest month in the park. That shouldn’t deter you from visiting, but make sure to plan accordingly, start your hikes early, choose some lighter traffic areas and book your campsites in advance when possible while also being flexible with your plans.
July is the start of the traditional dry season in Glacier and is the 2nd driest month of the year on average. Even so, rain still falls on an average of 8-9 days, with most of this in the form of afternoon convective showers and thunderstorms.
Thunderstorms are less frequent in Glacier compared to parks farther south in the Rockies, but they do happen somewhat frequently and lightning is definitely a hazard that should be taken seriously on the higher elevation and trails and more exposed areas.
Average high temperatures in July range from the upper 70s to low 80s at the lower elevations to the 60s at the higher elevations with average lows in the 40s. On the hottest days in July, high temperatures will reach the low 90s, while on the coolest days, low temperatures will fall into the 30s.
Given that July is the warmest month of the year, this is a great time to hang out at the many wonderful lakes in Glacier.
Pros of visiting in July: Warm temperatures, Rain is less frequent, All roads are open, Most hiking trails are accessible, Long days, Wildflowers are at their peak, All campsites and facilities are open, Logan Pass typically opens by early July
Cons of visiting in July: Crowded, Bugs are at their worst, Wildfires and smoke can be issues during dry years
Visiting Glacier in August
August is also a wonderful time of year to visit Glacier and hiking season is at its prime. You are less likely to run into snow hiking at the higher elevations in August than in any other month of the year.
August is the second busiest month of the year and only slightly less crowded than July with visitation at 91% of peak.
August is also the driest month of the year on average. Similar to July, rain falls on an average of 8 days in August, typically in the form of afternoon showers/thunderstorms. Occasionally, an early fall system will arrive in late August and bring a day or so of more widespread rain and even snow to the higher elevations, but this doesn’t happen every year.
Temperatures in August are very similar to those in July, though average temperatures do start to cool off some (especially at night) toward the end of the month. Another noticeable trend in August is that the days get shorter.
Perhaps the only downside about August (crowds aside) is that this tends to be the peak of fire season since it is the driest month of the year and the vegetation has had all summer up until this point to dry out. Wildfires and smoke conditions vary significantly from year to year and day to day.
Pros of visiting in August: Warm temperatures, Infrequent rainfall, All trails are accessible, All roads are open, Wildflowers are still good especially early in the month, Bugs start to die off by mid to late month, All campgrounds and facilities are open, Logan Pass is open
Cons of visiting in August: Crowded, Peak of wildfire and smoke season if it’s a dry year/dry summer, Days are starting to get shorter
Visiting Glacier in September
September is often a wonderful time to visit Glacier as the crowds are tapering off while access to the higher elevations remains good for most of the month (save for the occasional early season snowfall, which will quickly melt). Also, the bugs are gone in September!
Some facilities and campsites will start to shut down in September, but all roads remain open unless an early season snow forces a temporary closure (most likely on Logan Pass). Hiking access is good at this time of year, and it can be a beautiful time to visit as the fall colors start to appear.
Glacier typically remains crowded through Labor Day weekend, but then the crowds quickly start to dwindle after Labor Day. If you want to access the best of Glacier’s hiking trails with the most solitude, then September (post Labor Day) is your month. Overall, September is the 4th busiest month of the year, but visitation is only 39% of peak — a significant decrease compared to August.
September is the third driest month of the year behind July and August with rain falling on an average of 8-9 days. However, when it does rain in September, it can be longer in duration compared to the afternoon showers of mid-summer, as the first organized fall low pressure systems arrive at this time of year. Thunderstorms are also less common in September, but can still happen on occasion.
The first cool systems of the fall often bring snow to the higher elevations during September (and on more rare occasions, even the lower elevations), but snow that falls this early in the season melts quickly in the days to follow.
Average high temperatures in September range from the 60s at the lower elevations to the 50s at the higher elevations with average lows in the 30s. On the warmest days in September, high temperatures will reach the 80s, while on the coolest days, low temperatures will fall into the 20s.
Pros of visiting in September: Comfortable temperatures, Infrequent rains, Fall colors, Trails are accessible on most days, All roads are open (except for temporary closures during early season snowfalls), No bugs, More solitude after Labor Day, Fire season tapers off, Logan Pass remains open as long as it’s not snowing.
Cons of visiting in September: Shorter days, Early cold snaps can bring snow and chilly temperatures, Wildflower season is over, Some facilities and campgrounds start to shut down after Labor Day.
Visiting Glacier in October
October is a transition season and a time of year when much of the park remains accessible before shutting down for the winter. It is also a time when late season hikers and adventurers can find plenty of solitude as visitation is only 8% of the peak month.
Snow becomes more common across the higher elevations as the month progresses. Logan Pass often shuts down for the winter during the first week or two of the month, at which point higher elevation trails above 6,000 feet also start to become more difficult, both in terms of access and more frequent snow.
Hiking often remains accessible across the low to mid elevations well into late October before the winter snows really set in, though in some years it may be earlier. Hiking in October can be very beautiful, however, with the changing seasons.
Also, across the western and southern ends of the park, the unique larch trees change colors in October, usually peaking around mid-month. Larch trees are rare “deciduous conifers” whose needles turn yellow in the fall and drop off in the winter. They are spectacular in their fall foliage form, too!
Facilities and open campsites become very limited in October, although the Apgar and St. Mary Campgrounds remain open year-round and you can still camp in the backcountry with a permit as well. Otherwise, you’ll want to arrange camping or lodging accommodations for outside of the park.
October is typically the month of transition from the dry season to the wet season, and you can expect anything from days-long stretches of sunny, dry weather to multi-day cold, wet, and snowy systems. On average, there are 9-12 days of precipitation during the month of October and snow is possible at all elevations.
Average temperatures in October range from the 50s at the lower elevations to the upper 30s to low 40s at the higher elevations with average lows in the 20s and 30s. On the warmest days in October, high temperatures will reach the upper 60s to low 70s, while on the coldest days, low temperatures will fall into the teens.
Pros of visiting in October: Solitude, Can have stretches of sunny and dry weather, Many hiking trails are still accessible, Fall colors — especially Larch trees, No bugs, Fire season is over, Logan Pass may stay open through early/mid-month if weather stays nice, Off-season deals on lodging/food outside of the park.
Cons of visiting in October: Rain and snow become more frequent, Short days, High elevations start to become snowbound, It can get cold especially for camping, Logan Pass/upper portions of Going to the Sun Road start to close, Limited facilities and campgrounds, Can be tough to plan outdoor adventures in advance since fall weather patterns vary from year to year.
Visiting Glacier in the Winter (November-April)
True to its name (and also to its northerly latitude on the Canadian border and mountainous environment), winters are long, cold, and snowy in Glacier National Park. Most of the park shuts down in the winter, and it is generally not known as a park where destination travelers visit during the winter months.
However, Glacier is just as beautiful in the winter and is well worth a trip if you’re in the area. Combining a ski trip at nearby Whitefish Ski Resort (or Fernie in BC) with a side trip to explore Glacier National Park in the snow would make for an awesome trip.
Access to Glacier in the winter is possible along and just inside the boundaries, specifically from Apgar/West Glacier, Lake McDonald, Polebridge, Marias Pass, Lower Two Medicine Lake, and St. Mary.
Cross country skiing and snowshoeing on trails can be done from all of these access points. More adventurous and experienced winter backcountry travelers can also ski tour/backcountry ski inside the park, starting from Marias Pass or Lake McDonald primarily.
The Glacier National Park Ski and Snowshoe Trail Page has good information about winter trails in the park.
If you wish to backcountry ski, then please consult the Flathead Avalanche Center for current avalanche conditions.
Also, surprisingly two campsites in Glacier remain open during the winter — Apgar and St. Mary — if you’re looking for a unique experience. Winter backcountry camping is also available as well with a permit, which is free during the winter months.
Weather can be rather harsh during the winter, and prolonged cloudy/snowy stretches are common from November through January especially, meaning you might not see the higher mountains. When westerly flows are bringing heavy snow to the west side of the park, keep in mind that strong Chinook winds are likely impacting the eastern side of the park.
During the coldest months (December-February), average highs are in the 20s and 30s and average lows are in the teens, but during arctic cold snaps, temperatures can fall well below zero.
Pros of visiting Glacier in the winter: Solitude, Seeing the beautiful landscapes covered in fresh snow, Cross-country skiing, Snowshoeing, Backcountry skiing, Nearby downhill skiing at Whitefish, Winter camping
Cons of visiting Glacier in the winter: Limited access since most of the roads are closed, Mountains can be covered in clouds for days on end, Temperatures can be very cold
These monthly/seasonal summaries should give you a good idea of what to expect at various times of the year in Glacier. Next, we’ll take a look at the monthly weather averages at three locations in Glacier: West Glacier, Flattop Mountain (located on the Contiental Divide), and St. Mary.