Overview
- Heat advisories and Spare the Air ozone alerts are in effect across much of Northern and Southern California through midweek, with inland highs in the 90s to low 100s and officials urging limits on outdoor activity and burning.
- A cold front and Canadian high have delivered clear skies and much cooler mornings across the Midwest, Great Lakes and Northeast, producing scattered frost advisories and freeze warnings that threaten sensitive crops and outdoor plants.
- Parts of Montana are under Red Flag warnings and seeing near‑record warmth and gusty winds this week while models now favor a late-week trough that could flip conditions to much colder, wetter weather with accumulating mountain and valley snow.
- Coastal flooding, high surf and hazardous beach conditions are expected to develop along portions of the Bay Area starting Wednesday as higher tides and swells push water inland.
- Forecasters say near-term contrasts are confident but late-week outcomes remain uncertain, so residents should follow heat, air-quality and fire alerts now and watch forecasts for possible tropical interactions or a fast-moving cool-down this weekend.