This post explains the coming extreme heat threat to the Phoenix region and why temperatures will soar above 110°F this week. It also covers the limited but significant chances of storms and practical safety steps residents should take.
Drawing on decades of experience in weather hazards, I break down the forecast drivers and the likely impacts — including heat stress, dust, and wildfire risk. Clear preparedness advice is also offered.
What’s driving the heat and the forecast outlook
A strengthening ridge of high pressure moving westward is the primary driver pushing daytime highs back above 110 degrees in Phoenix by midweek. The ridge suppresses cloud cover and traps heat near the surface, causing temperatures to climb sharply.
The National Weather Service has issued an extreme heat watch beginning Wednesday, Aug. 20. Forecasts indicate highs around 112°F on Wednesday, Thursday, and Friday.
While the monsoon pattern will nudge storm chances into the forecast, widespread measurable rainfall across the Phoenix valley is still unlikely.
Storm chances, terrain differences, and associated hazards
Forecast probabilities are modest for the metro area: a 10–20% chance of storms starting Wednesday, increasing to 20–30% by Friday. Higher terrain east of Phoenix carries much greater odds — roughly 20–50% — and that’s where convective storms are most likely to form.
Even when storms are isolated they can produce severe local impacts:
- Gusty winds and blowing dust that reduce visibility and create hazardous driving conditions.
- Localized flooding in washes and low-lying urban areas from intense, short-duration downpours.
- Dry lightning and strong outflow winds that can spark or rapidly spread wildfires across parts of Arizona and southeastern California.
Who is most at risk and why prompt action matters
Extreme heat is more than uncomfortable — it’s a medical emergency for vulnerable populations. Infants, older adults, people with chronic illnesses, outdoor workers, and those without reliable access to cooling are at heightened risk of heat-related illness, which can escalate quickly to heat stroke.
The combination of high heat and the potential for dry lightning elevates wildfire risk. Even a brief storm with little rain can produce lightning that ignites dry brush, while strong outflow winds can carry embers and flames rapidly across landscapes.
Practical steps residents should take now
Prepare proactively: heat events strain power systems and emergency services. Your personal readiness can make a critical difference.
Key actions include:
- Stay hydrated — drink water regularly even if you don’t feel thirsty.
- Avoid outdoor activity during peak heat hours (typically late morning through early evening).
- Use sun protection: hats, lightweight clothing, sunglasses, and sunscreen.
- Check on vulnerable neighbors, family members, and pets frequently.
- Know the signs of heat-related illness — dizziness, confusion, rapid heartbeat, and lack of sweating in extreme cases. Seek medical help immediately if they occur.
- Have a plan in case of power outages: identify cooling centers, keep devices charged, and limit nonessential electricity use.
Monitor the National Weather Service and local emergency channels for updates. This is especially important if you live in or frequently travel to higher terrain east of Phoenix where storm odds and wildfire potential are increased.
Here is the source article for this story: Extreme heat is ramping up again in metro Phoenix. Here’s when to expect it