Late-summer heat wave to build in Washington, Oregon into first week of September
A dangerous late-summer heat wave will build across Washington, Oregon and British Columbia into early September, spreading toward the Pacific Coast and raising wildfire risk as California also heats up.
Autumn Anthony explains the differences in astronomical and meteorological fall.
One of the most significant heat waves of the year will build from the interior of Washington, Oregon and British Columbia toward the Pacific coast in the coming days, AccuWeather meteorologists say. Some areas east of the Cascades could approach their highest temperatures of the year so far.
August was hotter than average across much of the northwestern U.S. and southern British Columbia, with temperatures running several degrees above normal. Kamloops, British Columbia, has averaged 6.5 degrees Fahrenheit (about 3.5 degrees Celsius) above the monthly historical average temperature. In Portland, Oregon, temperatures have averaged 3.1 degrees higher than the 30-year norm.
Through midweek temperatures will approach or exceed 100 degrees in parts of eastern Washington, Oregon and southeastern British Columbia. At this level, temperatures will be 15-20 degrees above the historical average for early September.
Before this heat wave, Spokane, Washington, reached a high of 97 degrees in late July. There were multiple days during June, July and August with highs in the mid-90s. After reaching 99 degrees the first two days of September, the city will approach 100 once again on Wednesday.
The high temperature on September 2nd reached 102 degrees in The Dalles, Oregon. Highs could once again reach near 100 degrees Wednesday and Thursday.
Daily record highs, some dating back to the late 1800s, may be challenged in some locations.
The heat will expand westward and spill over the Cascades to parts of the Northwest coast once a nearby Pacific storm departs. That storm will help direct cool air from the Pacific shore inward along the coasts of Oregon, Washington and British Columbia for the first half of the week.
Portland, Oregon reach 90 degrees on Tuesday and is projected to reach near 90 through Thursday.
Marine air is expected to keep temperatures in check west of the Cascades. If offshore winds become strong enough, temperatures could rise 5–10 degrees higher along the Interstate 5 corridor in the U.S. and the Vancouver area in British Columbia.
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As the heat continues and becomes more extreme, people are urged to take it easy, when possible, during the middle of the day and the afternoon hours and to keep hydrated to avoid the risk of heat exhaustion and heat stroke.
The surging heat, combined with ongoing drought, will elevate the already high wildfire risk across the region.
Those spending time outdoors or using power equipment this week should use caution and follow all restrictions on open flames. Avoid parking vehicles with hot exhaust systems in tall brush, as this can quickly ignite a fire. If cooking outdoors, keep water nearby to extinguish any accidental sparks or flames.
The heat wave and ongoing wildfires will lead to a buildup of smoke and other pollutants in the region. Air quality will decline, which could have adverse effects on some individuals.
Farther south, heat also intensified in California and Nevada early this week, with highs running 5–10 degrees above average in most areas this week. Highs reached 100 and above in Sacramento, California both Monday and Tuesday with highs projected to be in the low to mid-90s through Thursday. In downtown Los Angeles, highs will be in the low 90s on Wednesday.
Marine air is expected to keep highs steady in San Francisco, generally in the upper 60s and 70s.
During the week, an uptick of tropical moisture in the eastern Pacific may spread from coastal Southern California to the deserts and the rest of the Southwest.
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