Overview

• The National Weather Service issued an Extreme Heat Watch for San Diego County’s mountains and deserts from Thursday morning to Friday evening, with triple‑digit highs and desert readings above 110°F.
• Extreme heat warnings and advisories cover parts of Southern California, with Los Angeles’ San Fernando Valley projected near 109°F on Thursday and some relief expected early next week as high pressure weakens.
• In Northern California, inland heat advisories begin Thursday as interior Bay Area and valley locations climb into the 90s and low 100s, and Sacramento Valley highs peak around 101–105°F late week.
• Fire danger is elevated under hot, dry and breezy conditions, prompting red flag warnings in Southern California through Saturday and the pre‑positioning of engines and crews ordered by Governor Gavin Newsom.
• National outlooks point to a cooldown later this week across much of the central and eastern U.S., while UK forecasts show a short cool spell with a possible brief return to 27–29°C next week and the Met Office monitoring ex‑Hurricane Erin for potentially unsettled weather.