Autumn heat wave to build in California, Arizona, Nevada
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Temperatures will continue to soar to record-challenging levels from the southwestern United States deserts to the California coast into this weekend, AccuWeather meteorologists say. Along with surging temperatures will come a renewed wildfire risk. A break in the heat is coming next week.
"A vast zone of high pressure will expand across much of the West this week, allowing for temperatures to climb well above historical average, even along the Pacific coast, where it can be more difficult for temperatures to climb," AccuWeather Meteorologist Haley Taylor said.
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When temperatures rise across the interior west, a cool breeze is often pulled in from the Pacific Ocean, helping regulate temperatures along many beaches and the Interstate 5 corridor. In this case, however, the flow will turn offshore, and the ocean's cooling effect will be minimal or not occur at all.
The San Francisco Bay Area will be one coastal hot spot in the pattern this week. Following highs in the 60s Fahrenheit over the weekend, which is several degrees below the historical average, high temperatures trended upward into the 80s on Monday and into the 90s on Tuesday.
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The current heat wave brought the highest temperatures of the year for San Francisco. The temperature at the airport reached 94 degrees on Tuesday. The previous peak in the heat this year was on July 2, when the high was 88. Temperatures may dip a bit into the end of the week before spiking again this weekend in San Francisco.
Los Angeles will continue to feel the heat in the pattern as well, although temperatures are likely to stop well short of high marks well above 100 degrees earlier this month. On Sept. 6, the temperature reached 112 in downtown Los Angeles, just 1 degree shy of tying the all-time record of 113 set in on Sept. 27, 2010. Highs will generally be in the 80s to low 90s in downtown Los Angeles this week. As such, temperatures will be 5-10 degrees above the historical average. From Saturday to Monday, widespread highs in the 90s are forecast for the Los Angeles Basin. Temperatures will reach or exceed 100 over the Inland Empire with highs of 110 or greater in Palm Springs.
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The desert cities of Las Vegas and Phoenix will be plenty hot in the pattern this week and into next. In both cities, record-tying or record-breaking temperatures will be at or above 100 through Tuesday of next week. In Phoenix, temperatures this past Tuesday shattered the October record of 107 from 1980 with a high of 113.
Much of the interior Southwest will remain hot into next week. However, temperatures are forecast to tail off a bit from Thursday to Friday along the coast, before a new surge of heat develops for the weekend.
Experts urge that as temperatures soar, people should increase their intake of non-alcoholic, non-caffeinated fluids, especially when working or exercising outdoors.
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Surging heat, low humidity levels and dry vegetation are prime ingredients for wildfire ignition, and people should avoid the use of open flames and be cautious when using any equipment outdoors that can produce sparks.
"Along with stiff offshore breezes, there will be an increased risk of wildfires across Southern California, mainly in the mountains and foothills, through Wednesday," Taylor said.
Breezes could drive any fires that develop toward coastal locations.
The ongoing Line, Bridge, and Airport fires have burned over 100,000 acres, but all are almost fully contained. The Line Fire had the lowest containment, at 76%, as of Tuesday evening.
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