Extreme heat in the Northwest brings elevated danger of wildfires

Many areas will experience temperatures above 100 degrees for the next several days

Hot Dry Windy Index weather fire wildfire
Hot Dry Windy Index, central Oregon.

The extreme heat that is gripping the Northwest this week is establishing weather conditions that are favorable for wildfires to spread more rapidly than usual. The Hot Dry Windy Index for Central Oregon on Monday and Tuesday is far above the 95th percentile. Other locations in Oregon and Washington also show the HDWI at high levels this week, generally above the 90th percentile and higher. (We first wrote about the HDWI in 2019.)

Many areas in the Northwest will have high temperatures above 100 degrees for the next several days. Here is an excerpt from an article published Monday at Oregon Public Broadcasting:

Seattle, Portland and other cities broke all-time heat records over the weekend, with temperatures soaring well above 100 degrees Fahrenheit. Forecasters said Monday would be worse, with the mercury possibly hitting 110 F in Seattle and 115 F in the Portland area before it begins to cool Tuesday.

In Eugene, the U.S. track and field trials were halted Sunday afternoon and fans were asked to evacuate the stadium due to extreme heat. The National Weather Service said it hit 110 F in Eugene, breaking the all-time record of 108 F. Portland reached 112 F Sunday, breaking the all-time temperature record of 108 F, which was set just a day earlier.

The temperature hit 104 F in Seattle. The weather service said that was an all-time record for the city better known for rain than heat and was the first time the area recorded two consecutive triple digit days since records began being kept in 1894.

The heat wave stretched into British Columbia, with the temperature in Lytton, a village in the Canadian province, reaching 115 F Sunday afternoon, marking a new all-time high recorded in Canada.

Red Flag Warnings June 28, 2021 fire wildfire
Red Flag Warnings June 28, 2021.

Red Flag Warnings are in effect Monday for a number of areas in California, Washington, and Oregon. The Fire Weather Watch areas on the map above for locations in California and Nevada are for thunderstorms and strong outflow winds Tuesday afternoon through late Tuesday night.

So far the extreme heat has not led to large fires in Washington and Oregon. Monday’s Situation Report does not include any that are less than 95 percent contained. However the 1,446-acre Lava Fire near Weed, California, 37 miles south of the Oregon Border, bears watching. Started from lightning on June 25, it will be subject to winds gusting to 26 mph Monday afternoon.

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Author: Bill Gabbert

After working full time in wildland fire for 33 years, he continues to learn, and strives to be a Student of Fire.

3 thoughts on “Extreme heat in the Northwest brings elevated danger of wildfires”

  1. I’m seeing HDW index values here over 250 (near Winthrop, WA) even with light winds. Tomorrow there are even higher temperatures forecast along with gusty winds to 20mph.

    Note that the methods for calculating HDW from the paper typically produce very low values in the presence of light winds, so seeing a value that high is remarkable.


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