Northwest Montana

Issued: 05/11/2026 6:40 p.m. MDT

Tonight...Fair skies. Lows in the mid 30s to mid 40s with mid 40s around 5000 feet. Light wind.

Tuesday…Mostly sunny and very warm with a few afternoon clouds. Highs in the 80s to near 90 except locally upper 70s cooler higher elevation valleys near Trego with near 70 around 5000 feet. Local east to northeast wind 5 to 15 mph with gusts to 20 mph through favored canyons, along portions of Lake Koocanusa and across ridge tops.

Tuesday night…Variable cloudiness and very mild. Isolated sprinkles or light showers possible towards dawn along the Idaho border. Lows in the mid 40s to mid 50s with lower 50s around 5000 feet. Light wind except ridge top winds north to northwest 10 to 15 mph.

Wednesday...Considerable cloudiness and cooler with scattered to numerous afternoon showers and thunderstorms. Some thunderstorms may produce heavy rain, small hail, gusty winds and frequent lightning. Highs in the 70s with upper 50s around 5000 feet. West to southwest wind 10 to 20 mph in the afternoon with gusts to 30 mph through favored canyons, along portions of Lake Koocanusa and across ridge tops. Gusty winds possible near thunderstorms.

Extended Outlook(Thursday through Monday):

Thursday...Locally breezy to windy with a chance of showers, mainly in the morning. Lows in the 40s with mid 30s around 5000 feet. Highs in the upper 50s to mid 60s with mid 40s around 5000 feet.

Friday through Sunday...A chance of showers and locally breezy. Lows in the 30s all elevations. Highs in the mid 50s to mid 60s with upper 40s around 5000 feet.

Monday...Dry and seasonal. Lows in the lower 30s to lower 40s with upper 30s around 5000 feet. Highs in the 60s with mid 50s around 5000 feet.

In-Depth Weather Discussion for Northwest Montana/North Idaho/Northern Rockies 

Issued 05/11/2026 7:10 p.m. MDT / 6:10 p.m. PDT

SHORT TERM (MONDAY NIGHT THROUGH WEDNESDAY):

     Upper level ridge will continue to migrate across the Northern Rockies overnight into the day on Tuesday with the surface thermal trough following as well. For much of the day on Tuesday the ridge axis along with the thermal trough will remain across Central Washington before shifting east of the region overnight Tuesday into Wednesday as a compact but somewhat dynamic upper level closed low approaches the Oregon coast. Temperatures will warm considerably on Tuesday with enough mixing from a northeast gradient to help the warmer air aloft to mix down to the surface and most valley locations will likely see their warmest day of the year on Tuesday. High temperatures will average nearly 20 degrees above mid May climate seasonal climate averages. The approaching upper level low will need to be watched carefully as our region will be in the favored northeast quadrant of the upper level low with favorable diffluent flow aloft. If the low shifts a bit further north then we could see our first outbreak of elevated convection fire off overnight Tuesday into early Wednesday morning. This would likely feature quite a bit of lightning and thunderstorm activity with locally heavy rains and hail possible with this convection. The moistening of the atmosphere through airmass modification will then make surface based convection more likely on Wednesday especially by late in the day which is when CAM models are showing the most organized shower activity across our region. Preliminary rainfall amounts range between about a quarter to a half inch but some areas could see less and others possibly considerably more especially if a thunderstorm moves overhead. Temperatures will drop 15 or so degrees on Wednesday due to all of the cloud cover and showers around. In addition, surface pressure falls will take place east of the Continental Divide along with surface pressure rises along the West Coast. This will create a tight thermal gradient from the southwest across the Northern Rockies with gusty southwest winds developing on Wednesday.

LONG TERM (WEDNESDAY NIGHT THROUGH MONDAY): 

     Still a fair amount of uncertainty in the extended forecast period with a rather robust zonal North Pacific jet residing to the south of a rather cold upper level low in the Gulf of Alaska. Where this feature sets up will largely influence how much precipitation we get this upcoming weekend with outcomes ranging from a few showers and breezy to windy conditions to rather wet and yes snow up in the mountains. This weekend is a rather busy one with several activities ongoing throughout our region with the annual Lost in the 50s event in Sandpoint and the annual Eagle Valley community auction in Libby. For now have simply included a chance of showers for the Friday through Sunday period although it is not likely to be raining the entire time. Again keep this in mind if you are planning an early season backcountry trip as snow levels could be down to near 5500 feet this weekend. By next week the pattern looks to modify a bit with slightly higher heights and a bit of warming but by and large temperatures remaining near seasonal averages for mid May which is lower to mid 60s in the valleys and near 50 up in the mountains.