Historic Pacific Northwest heat wave is almost here

SEATTLE - Yesterday was a very comfortable day with highs in the mid 70s. This morning, some marine layer clouds have advanced a bit inland, but not as far as yesterday morning. Any morning clouds will break for afternoon sunshine. As a result Puget Sound lowlands will be several degrees warmer than yesterday with most of us getting into the 80s.

Tomorrow we will start our ascent into some pretty hot weather by the weekend. Friday looks to be up in the 85 to 90° range. The NWS has issued an Excessive Heat Watch which begins on Friday and lasts into Monday. This will become an excessive heat warning as we get closer to this time period. The Q13 weather team has issued Weather Alert Days for Sat/Sun/Mon. 

One thing that's making this hot weather so hot is the downslope warming wind E/NE Cascadia wind. Compressing air heats it up -- and we'll see that happen as the ridge of high pressure off shore moves to a sweet spot over southwestern British Columbia. 

This period will have some of the hottest temps of the year as the mercury goes into the 95 to 100° range each afternoon. Seattle metro has only achieved triple digit temperature readings 2 other times since record-keeping began in 1894. Now it could happen two days in a row! 

For a region unaccustomed to such heat and only a third of homes with AC, this will be a dangerously hot stretch of weather. Normal for this part of June is 73.  Overnight lows will be uncomfortably warm as well, like near 70° for most of us around Puget Sound. Normal lows are around 53. This weather pattern does not include any precipitation for the foreseeable future either so fire risk will increase. Today is our 10th dry day in a row already.  

Our water temperatures will remain very cold for individuals looking to beat the heat. Puget sound water temperatures remain in the low 50s, Lake Washington has warmed to only 66 so far, and some of our snowpack fed rivers will be only in the upper 40s/low 50s. Practicing fire and water safety will help save lives. -Tim Joyce 

Q13 FOX WEATHER RESOURCES: 

DOWNLOAD: Q13 Weather and News Apps 
WATCH: Forecast and Radar 
READ: Closures and Delays 
CHECK: Latest Weather Alerts and Live Traffic Map 
INTERACT: Submit your Weather Photo
FOLLOW: Lisa Villegas, MJ McDermott, Tim Joyce, Erin Mayovsky, Grace Lim and Scott Sistek