Highlights
- Phoenix recorded 109 degrees as a multi-day extreme heat event began building Monday, Aug. 17.
- An Extreme Heat Watch is in effect from Monday morning through Friday evening, with afternoon highs forecast between 109 and 113.
- Overnight lows are expected to hold between 88 and 92, offering little relief, and rain chances across the lower deserts remain minimal.
- Phoenix hiking trails are closing during the warning period, according to AZFamily reporting.
Phoenix hit 109 degrees Monday as high pressure and dry air settled across Arizona, triggering an Extreme Heat Watch through Friday evening, with afternoon temperatures forecast to reach 113 and overnight lows holding between 88 and 92, according to FOX 10 meteorologist Erica Horvatin.
The forecast is corroborated by the National Weather Service Phoenix office, which shows major heat-risk conditions developing through the week with storm chances limited to Arizona high terrain and southeast Arizona. The lower deserts are expected to remain dry, eliminating any monsoon relief that could moderate temperatures.
A Weather Underground severe alert for Phoenix specifies the watch parameters: afternoon temperatures 109 to 113, overnight lows 88 to 92. AZFamily's First Alert Weather confirms an Extreme Heat Warning in effect Monday through Friday evening, with First Alert Weather Days declared across the period.
The city of Phoenix has begun closing hiking trails in response to the warning, AZFamily reported Sunday.
The Extreme Heat Warning remains in effect through Friday evening.
Sources
Every factual claim in this article traces to one of the sources below. See how we work for the editorial process.
- Fox 10 Phoenix retrieved 17/08/2026 01:25
- weather.gov retrieved 17/08/2026 01:25
- wunderground.com retrieved 17/08/2026 01:25
- AZ Family (3TV/CBS5) retrieved 17/08/2026 01:25
- AZ Family (3TV/CBS5) retrieved 17/08/2026 01:25
Authored by The Scottsdale Signal. Drafted by AI from primary-source material under our beat-specific editorial guides; reviewed by humans before publish under our five-gate process. Sources retrieved at 17/08/2026 01:25. Every claim traces to a source.
