Overview

• Surging monsoon moisture is boosting thunderstorm chances through Wednesday in California, with the Sierra and Foothills most likely to see lightning and isolated strikes possible in some valley locations.
• Because lower levels remain dry, the National Weather Service warns many storms may produce little rain, elevating the risk of dry lightning and new wildfire ignitions across interior mountains.
• Northern California’s brief inland heat spike is forecast to ease midweek, with valley highs stepping down from early‑week 90s to milder readings by late week.
• A strong cold front will sweep the Great Lakes and Ohio Valley Wednesday night into Thursday, bringing showers and a notable cooldown; Northeast Ohio is forecast to receive about 0.5–1.0 inch of rain before highs fall to the mid‑60s.
• New England and the Mid‑Atlantic stay dry and comfortably warm through midweek, with rain chances increasing late week as the front approaches, while Chicago turns cooler after Wednesday and Michigan prepares for breezy, cooler, wetter conditions.