Northern California will stay unseasonably cool and unsettled through midweek, with temperatures running about 10 degrees below normal for late May and a chance of scattered showers, isolated thunderstorms, and some Sierra snow. The strongest impacts are expected Tuesday through Thursday as a weather disturbance spins over Northern California and gradually shifts east by Friday.
In the Valley, highs are expected to hold in the low to mid 70s on Tuesday and Wednesday, before edging closer to 80 degrees by Friday and reaching the 80s over the weekend. The foothills should remain cooler, with highs in the mid to upper 60s, while Sierra communities will see highs mainly in the low to mid 50s. Tahoe is forecast to stay especially cool, with highs around 48 degrees on Wednesday.
Windy conditions in the Sierra and Tahoe Basin are easing, though it remains breezy to gusty at times, especially early Tuesday morning. Gusts near 45 mph were reported around South Lake Tahoe Airport overnight, and scattered clouds over the high country signal the changing weather pattern. Some cloud cover may produce virga, where precipitation appears to fall from clouds but does not always reach the ground.
The best chance for showers and thunderstorms will be over the Sierra and foothills, including Plumas, Sierra, and Nevada counties, where a rumble of thunder could develop Tuesday afternoon. A stray shower cannot be ruled out in the Valley, including areas near Sonora and Stockton, but widespread rainfall is not expected there. More scattered foothill showers and thunderstorms are possible Wednesday, with the disturbance lifting a bit farther north Thursday before moving out of the region.
Snow is also possible above 6,000 feet, and slushy snow may develop at Sierra pass levels from late Tuesday into Thursday. Forecasters do not expect major travel impacts, but mountain travelers should be prepared for cooler, unsettled conditions. After the system exits, temperatures are expected to improve heading into the weekend, bringing a return to warmer weather across the region.
Overall, the pattern will feel more like early spring than late May, especially in the Sierra, where cloudy skies, intermittent showers, and a lingering chill will continue to define the week.
