Welcome to the 2026 Summer Western U.S. "Daily Snow"! I'll be posting weather discussions focused on mountain weather and outdoor recreation a few times per week throughout the summer season.

Memorial Day weekend is the unofficial kickoff of the summer season, so let's get to it...

Friday Afternoon Big Picture Weather Update:

Most of the West is heading into a warming and drying trend, following an active week in which we saw cooler temperatures and significant mountain snowfall across portions of Colorado and Wyoming.

On Friday, the low-pressure trough responsible for active weather in recent days is exiting eastward onto the plains, but an unsettled west/northwest flow remains on the backside of this trough, stretching from Tahoe into Southern Colorado and Northern New Mexico. 

Pockets of convective instability will favor early to mid-afternoon thunderstorm development across some areas on Friday afternoon.

In California and Nevada, our in-house StormNet Model (free to download in the app store) favors a high probability of early afternoon thunderstorms on the south side of Tahoe, as well as across the Eastern Sierra near and east of the CA/Nevada border. 

The best chance of storms in the Sierra is expected between about noon and 3:00 pm PT before the atmosphere stabilizes late in the day. NW to SE storm movement will largely keep storms anchored to the higher terrain.

Locally heavy downpours are possible, but again, mainly over the higher terrain with limited rainfall potential for the valley and lowlands.

Across Colorado and New Mexico, most regions are looking at a dry and thunderstorm-free day, but there are a few exceptions.

A moderate (25-50%) threat of thunderstorm development is favored around Pikes Peak and Colorado Springs, with a higher threat (pockets of 50-90% risk) expected over the Wet Mountains of Southern Colorado and near the CO/NM border around Raton Pass. 

 

The peak lightning threat across these regions is expected between about 2pm and 6pm MT, with storms traveling fairly quickly from WSW to ENE. Small hail is certainly possible with stronger thunderstorms, but the risk of large hail (1+ inch diameter) is very low along the I-25 corridor. 

Along and west of the Continental Divide, mainly dry conditions are expected, though some isolated storms couldn't be ruled out in the San Juans.

Saturday (May 23) to Sunday (May 24):

Saturday is shaping up to be a beautiful day throughout the West with warmer temperatures and mainly dry conditions, save for some very isolated thunderstorm chances across the Great Basin.

On Sunday, the pattern starts to turn a bit more active in response to a developing trough off the California coast. Mid-level moisture and instability will increase, leading to a modest threat of afternoon thunderstorms across the Sierra and the Rockies.

Rainfall looks to be on the lighter side with most thunderstorms that develop on Sunday, meaning that lightning and gusty winds will be the main threats to watch out for.

When using our StormNet Model, note that we project hourly lightning risk out to 2 days in advance, followed by 12-hour increments beyond 2 days.

In other words, check back in with the model as we get closer to hone in on the hourly projections, and also be aware that accuracy further increases the closer we get to storm development.

Monday (May 25):

The pattern will start to turn more active on Memorial Day. First, a deep trough with an upper-level low pressure center ("upper low") will set up over the Pacific Northwest, leading to a transition to wet weather.

Meanwhile, a trough will also move into the Southwest with an uptick in moisture and shower/thunderstorm chances expected across the Southwest into the Rockies. 

In the Pacific Northwest, nice weather will prevail on Saturday and Sunday, with rain moving in early on Monday and likely continuing for most of the day. The heaviest rainfall is expected over the Olympic Peninsula, Vancouver Island, and BC Coast Range, where totals could exceed an inch in many areas.

In the Cascades, rainfall amounts are generally projected to range from 0.25 to 0.75 inches on Memorial Day, while the Inland Northwest may see rain chances hold off until Monday evening. 

Check out our 5-day forecast range charts for precipitation in the following locations in the PNW:

Hoh Rain Forest, Olympic NP:

Longmire, Mt. Rainier NP:

Seaside, Oregon:

In addition, colder air will move into the PNW on Monday, with snow levels projected to drop to around 5,000 feet in the Cascades on Monday night.

Here is our snow level forecast range chart for the Paradise Visitor Center near Mt. Rainier, which is located at an elevation of 5,400 feet.

Across the Rockies and Southwest, an uptick in thunderstorm chances is expected region-wide on Monday in response to the troughs over the Southwest and Northwest.

StormNet projects the highest risk of lightning across Arizona and New Mexico, which makes sense given the location of the trough over the Southwest, which favors large-scale "lifting" that should generate more thunderstorms. Also, there is an overnight risk of thunderstorms in Arizona and New Mexico on Sunday night and into Monday morning. 

Elsewhere, the main lightning risk across the Rockies should be expected on Monday afternoon, with Monday morning likely offering a better weather window. Rainfall amounts are projected to be heavier across the Southwest into the San Juans, with lighter rainfall further north across the Central and Northern Rockies.

Also, within Colorado, StormNet is projecting a higher lightning risk across the San Juans and the Southern Front Range (south of I-70), with more isolated activity and lower probabilities elsewhere. But keep in mind that Monday is still a few days away, so this could always change between now and then.

Tuesday (May 26) to Thursday (May 28):

The middle of next week looks more active throughout the West, as the upper low over the PNW is projected to dip southward and stall over the Great Basin for several days. 

This will result in a wetter pattern with frequent rounds of showers and thunderstorms expected across the Interior West from the Sierra to the Northern and Central Rockies.

Here is a 3-day precipitation projection from the European AIFS Ensemble Model from Tuesday through Thursday, to give a general idea of how this pattern may shake out. But keep in mind, this is subject to change as slow-moving upper lows can be tough to pin down this far out.

Also, thunderstorms are expected to develop each afternoon across the Rockies during this stretch.

Check out our 7-day StormNet lightning risk chart for Berthoud Pass in Colorado's Front Range. Notice how the threat generally increases each day heading into the middle of next week. 

These lightning risk charts can be viewed for any location in the U.S. in the StormNet app by tapping on the graph symbol in the bottom left-hand corner of the screen (this will then show a down arrow, as seen below), and by hovering the target over the location you want to view the risk for.

Outlook for May 29 to June 5:

During the end of May and into the first of June, longer-range models are hinting at a trough-dominant pattern setting up over the West, with a southwest flow favoring above-average moisture levels across most of the West.

This should lead to a fairly active pattern with routine afternoon shower and thunderstorm chances for many areas, though the day-to-day details are uncertain this far out of course.

This pattern would also favor near to below average temperatures across the Northwest and the Southwest, and above-average temperatures (but not excessively above average) from California into the Northern Rockies.

The next map below shows projected week 2 precipitation totals (May 29 to June 5) from the European AIFS Ensemble Model, which represents the average of 50 simulations of this model. Since we are talking 1-2 weeks out, using an ensemble average is best to get a big picture idea. 

Most regions of the West are projected to receive meaningful rainfall during this stretch, with the Pacific Northwest, Eastern U.S. Rockies, and BC and Alberta favored for the highest totals. 

Thanks so much for reading, and have a great holiday weekend!

Next update on Tuesday (May 26).

Alan Smith 

P.S. In case you missed it, we published a summer season outlook for North America here, with an emphasis on the emerging El Niño and how it could influence summer weather patterns.

View → North America Summer 2026 Outlook

OpenSnow: Your Daily Weather App

Ready to replace those "other" weather apps?

As the snow begins to melt and summer conditions quickly take over, remember that you can always use OpenSnow as your daily weather app during the non-winter months.

Features →

My Location 15-Day Forecast
Severe Weather Alerts
Global Storm Forecast
Super-Res Radar + StormNet
Current & Forecast Radar w/ Precip-Type
Recent Satellite Maps
Wildfire Smoke Forecast Maps
Active Fire & Perimeter Maps
3D & Offline Maps
And Much More!

Getting Started

1. Go to the OpenSnow app or OpenSnow.com
2. Tap the "My Location" tab for 15-day forecasts.
3. Tap the "Maps" tab for high-resolution maps.