Excessive Heat, Smoke, and Critical Fire Weather

For residents of the Inland Northwest, the heat has likely felt relentless to most of us.  While hot temperatures may feel normal given that it's July, the data suggests otherwise.  The current stretch of hot weather is about to break some more records (more on that later).

Most of the region had a much drier than normal spring and early summer.  Here is a look at percent of normal precipitation over the past 120 days.  

Percent of normal precipitation past 120 days (March 20th - July 17th, 2024)

Enhancing the dry conditions, has been the relentless heat over the region.  Spokane has now reached the 90 degree mark for 14 consecutive days (including today).  The chart below shows the normal range in temperatures (brown shading), with the observed values shown by the blue bars.  The readings on July 8th, 9th, and 10th set records for the date.

Spokane International Airport Observed, Normal, and Record Temperatures for July 2024

The record streak of 90 degree days is 15, so this will easily be broken.  In fact, the heat will intensify.  Here is a look at a map of Excessive Heat Warnings that are in place over much of the region.

Map of NWS Excessive Heat Warnings and Heat Advisories as of 8 PM July 18th, 2024

The number of 100 degree days is also noteworthy.  So far Spokane has reached 100 degrees three times this season (through July 18th).  The record is 6, which recently happened twice in 2022 and 2021.  With the forecast reaching that mark Saturday, Sunday, and Monday there is good chance that record will be tied yet again.  Of course one more heat wave this summer could push us above that.

Here is a look at forecast high temperatures from July 19th-23rd, from the forecast published on July 18th.

The heat is likely to peak on Sunday for most of the region (except parts of North Idaho).  And you'll notice a cool down on Tuesday with highs in the lower 90s.  This could cause some problems (more on that later).

Of great concern is the recent lightning event that occurred on July 16th and 17th across the northwest.  Several wildfires were ignited, especially across Oregon, just east of Grand Coulee, and in the North Cascades of Washington.  There were also some new fire starts in the Central Panhandle Mountains in Idaho.  Here is a snapshot of fires across the region as of July 18th. 

With so many fires, several areas of smoke were noted on satellite this evening (July 18th)

Satellite image evening of July 18th, with smoke highlighted inside pink area.

With record heat this weekend, the expectation is that several of these fires will become larger, putting out an increasing amount of smoke.  Here is one model projection showing smoke over the region the next couple of days.

5 PM July 18th HRRR Total Smoke forecast valid from 8 PM July 18th-5 PM July 20th, 2024

Surface smoke impacting air quality is expected to continue to be most impacted near wildfires.  But hazy skies from regional wildfire smoke will be prevalent over all of the region.

Finally, as mentioned earlier, with fires becoming more active through the weekend, there is a concern of dry, breezy winds as temperatures begin to trend cooler early next week.  Below is the National Blend of Models output for the chance of wind gusts exceeding 30 MPH on Monday.

Any new or existing fires in Central Washington will have the potential to spread rapidly.  These gusty winds will likely continue through at least Tuesday.

So, be prepared for excessive heat, potential for increased smoke into early next week, and then critical fire weather conditions in Central Washington on Monday (and likely into Tuesday as well).