July 30, 2026. A heat dome is sitting on Arizona this weekend. Local forecasts have Phoenix near 116°F on Friday and Saturday (July 31 and August 1)—hot enough to tie daily records—under an Extreme Heat Warning for southern, central, and western Arizona through Sunday evening.

What’s forecast

Arizona weather desks (AZFamily, FOX 10 Phoenix, Arizona Republic) are calling for:

• Wednesday–Thursday: Phoenix climbs through the low-to-mid 110s (about 111°F Wednesday, ~113–114°F Thursday).
• Friday–Saturday: Forecast highs near 116°F, with a real chance of matching the calendar-day records.
• Sunday: Still extreme—forecasts near 115°F—before a slight easing early next week.
• Nights stay dangerous: overnight lows have been stuck in the upper 80s to low 90s. Phoenix recently matched its warmest overnight low on record (97°F) on July 24–25 mornings, then posted another very warm night later in the week.

Rain chances in the Phoenix Valley are near zero for several days. Dry ground under high pressure tends to run hotter, not cooler.

Regional context from national coverage (NPR / Fox Weather):

• This is described as the third major U.S. heat dome in about a month.
• Roughly 70 million people were under the broader heat footprint as the dome tracked from the South/Midwest toward the West.
• Las Vegas has been on a multi-day streak of highs at or above 110°F, with more triple-digit days expected.
• Forecast centers flag the wider Desert Southwest / Four Corners corridor—including parts of Southern California and Death Valley—for life-threatening weekend heat, with some outlooks mentioning highs in the high teens Fahrenheit above seasonal normals.

Heat vs UV

Heat warnings get the headlines. UV still runs alongside them when skies stay clear.

South Florida is a useful contrast this same week. Boca Raton–area forecasts for late July into August 2 called for:

• daily highs mostly in the low-to-mid 90s°F
• heat-index / RealFeel values near 110–112°F on the worst humid days
• peak UV Index values of 11.0–12.0 (Extreme) on several dates, including July 26, July 28, and August 2
• unprotected midday exposure timed to skin damage in under about 15 minutes on Extreme UV days

Arizona’s dry heat feels different from Florida’s humid heat, but both patterns punish outdoor time: one through radiant heat and full sun, the other through humidity plus Extreme UV between storm cells.

Heat tells you whether your body can cool. UV tells you how fast unprotected skin burns. This weekend in Phoenix, you need both answers.

Through Sunday

If you are in metro Phoenix or under the Arizona Extreme Heat Warning:

1. Treat Friday–Sunday midday as a no-go for long outdoor work unless it is essential and shaded.
2. Move exercise, errands, and kids’ outdoor time to early morning—before the daily climb into the 110s.
3. Do not trust overnight “cool-down.” Lows in the 90s mean your body may not fully recover between days.
4. Check live UV as well as temperature on the homepage. Clear desert sun routinely pushes summer UV into Very High / Extreme bands even when the weather story is only about thermometers.
5. Hydrate and watch heat-stroke signs (confusion, severe fatigue, nausea, headache). Heat stroke is a medical emergency; UV planning does not replace cooling someone fast.

If you are elsewhere under the shifting dome (Four Corners, Southern California deserts, lingering Gulf/South humidity), use the same rule: read the alert for your county, then check today’s UV peak before you commit to midday sun.

Beyond this weekend

Coverage has framed recent U.S. heat pulses as unusually persistent. For readers here, the useful takeaway is narrower: when a city is chasing record 116°F highs, outdoor time breaks into short, protected windows—not an all-afternoon default.

Sources and limits

This update summarizes publicly reported forecasts and alerts as of July 30, 2026 from Arizona local weather desks and national heat-dome coverage. Forecasts change. Always defer to the latest National Weather Service products for your county.

UV readings on UV Index Today are estimates for everyday sun-safety planning, not medical advice. For SPF and related Q&A, see the Guide. For your location’s current numbers, open the live UV index.