PHOENIX (March 12, 2026) – Valleywise Health physicians are issuing health warnings amid a historic March heat wave expected to push temperatures past 100 degrees next week.
A sudden heat surge can be especially dangerous — especially for out-of-town visitors — because our bodies haven’t had enough time to adjust to the high temperatures, raising the risk of heat stress and heat stroke.
“One of our concerns with early spikes in outdoor temperatures is that our out-of-town visitors are not acclimatized to the heat,” said Dr. Paul Pugsley, emergency medicine physician at Valleywise Health Medical Center. “Their bodies aren’t physiologically ready to ramp up and respond, and they might not recognize the signs of early heat illness.”
Forecasters are predicting a high temperature of 102 degrees on Tuesday, March 17, breaking a record for the earliest reading of 100 degrees in Phoenix.
Valleywise Health physicians warn that the intense heat is particularly dangerous at a time when residents and visitors are heading outdoors to the ballpark or to popular trailheads. Visitors unaccustomed to Arizona’s extreme heat may not recognize warning signs of heat stress.
“They might not realize they’re becoming dehydrated because their skin is dry. They might not recognize the signs of early heat illness and just push through,” Dr. Pugsley said. “They might just think they’re becoming fatigued or light-headed.
“When it becomes so hot this fast we just prefer that folks not exert themselves when they’re not used to this weather.”
Other at-risk groups include people with chronic health conditions, vulnerable adults and people who can’t afford air conditioning. Pugsley urged friends, family members and neighbors to check on the elderly who may be impacted by indoor heat.
Signs of heat exhaustion include headache, nausea, dizziness, thirst, sweating and an elevated body temperature. You should seek medical attention immediately.
Other tips:
- Stay hydrated when spending time outside by always having a water bottle on hand.
- Limit alcohol and drinks with high levels of sugar or caffeine.
- If working or exercising outdoors, try to do it in the early mornings or evening hours when temperatures are cooler.