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Extreme Heat Warning San Diego: Record-Breaking Heat Wave With Dangerous Humidity Hits County

By CALWIRE Weather Desk — Thursday, September 10, 2026
By CALWIRE Weather Desk  |  PUBLISHED: Thursday, September 10, 2026
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San Diego County is getting slammed by a record-breaking heat wave that's not letting up, and the dangerous part isn't just the temperature - it's the humidity. A blast of tropical moisture is making conditions feel suffocating across the region, raising serious health concerns heading into the Labor Day holiday stretch, according to early reports.

Related: Extreme Heat Watch San Bernardino County Mountains: What to Know Tuesday–Friday · Extreme Heat Warning in Central Valley: Triple-Digit Temps Before Cooldown Arrives

Temperatures have pushed into extreme territory and broken records across Southern California, with San Diego County among the hardest-hit areas. The combination of oppressive heat and unusually high humidity is what's making this wave especially punishing - your body just can't cool itself down the way it normally would in dry Southern California air.

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And don't expect relief tonight. According to KPBS, the record-hot Labor Day weather is not over yet for San Diego County. Residents are being urged to take the heat seriously, especially vulnerable populations like the elderly, young children, and those without air conditioning.

What's Making This Heat Wave Different

California doesn't usually deal with tropical humidity, but that's exactly what's hitting right now. The Los Angeles Times describes the conditions as "oppressive," and Yahoo News reports a dangerous surge of tropical moisture is driving temps to extreme highs across the state. For San Diego, a city that usually catches a break from ocean breezes, this is an unusual and serious situation.

See also: Extreme Heat Warning California: Heat Dome Expanding West With Triple-Digit Temps Expected · Heat on the Horizon: Southern California Braces for Another Punishing Wave This Week

What You Should Do Right Now

Cooling centers are typically activated during extreme heat emergencies in San Diego County - check with county services for your nearest location. Stay hydrated, avoid going outside during peak afternoon hours, and check on neighbors and family members who may not have AC. If someone is showing signs of heat stroke, call 911 immediately.

This Is Developing

This is a developing story and conditions are changing fast. Record highs and exact heat advisory boundaries may be updated throughout the day. Check back for the latest on this heat emergency as more information becomes available.

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Filed Under: Weather Extreme Heat Warning San