No relief: Heat wave plaguing Southwest set to expand

SAN FRANCISCO (CN) — Oppressive heat that has been punishing much of the U.S. Southwest this month has set its sights on Central California and beyond in the coming days.

The heat wave during the Independence Day holiday left many parts of California and the West in extremely hot, dry conditions, raising concerns about the danger of fireworks shows and wildfires. But cities across the Southwest have faced a relentless “heat dome” all month: so far, the National Weather Service has recorded nine consecutive days of temperatures above 110 degrees in Arizona. The state’s longest stretch of consecutive days over 110 degrees was 18, in 1974.

The heat dome will begin expanding northward this week. “Looking at our high temperature forecast, we can’t help but feel like we’ve fallen into a ring of fire,” the National Weather Service’s Sacramento office tweeted.

Meteorologists in Sacramento reported Monday that “some minor to moderate heat risk is becoming evident throughout the valley during this time frame, primarily driven by warming overnight low temperatures."

The forecast shows very high probability — 85%-95% — of daytime highs exceeding 100 degrees Fahrenheit throughout the Sacramento Valley and many inland areas. And there will be limited relief overnight, with lows expected to top 70 degrees throughout the northern Sacramento Valley.

Still recovering from disastrous winter and spring flooding, the Central Valley is about to bake. Fresno and Bakersfield will likely see high temperatures of at least 110 degrees, with poor overnight recovery during the weekend.

“Most of the valley will have at least 50% chance of overnight lows into Sunday being above 70 degrees, with the exception of Merced and Madera,” forecasters said.

That puts the San Joaquin Valley in a major and even extreme heat risk through the weekend, and officials are warning residents to avoid time outdoors as much as possible while staying hydrated to prevent heat illness or death.

The heat waves will also boost melting of the Sierra’s historic snowpack.

“With the overall warming trend that has been ongoing over the past few months, mountain snowmelt continues to occur,” the report warned. “As a result, area rivers and creeks are still running fast and cold.”

California and much of the West are out of the yearslong drought thanks to that snowpack, but experts have warned that more time is needed to ascertain how much the extremely wet winter will alleviate the lasting effects.

As for whether the heat wave is a by-product of the El Niño weather pattern that’s been growing in the Pacific Ocean, experts think not.

“This type of ridge is something that typically set up around this time of year — it’s just a little stronger than usual,” National Weather Service meteorologist Dalton Behringer said.

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