Short heat waves aren't too uncommon in summer -- there were several times in the 1990s where we'd have 2-3, even 4 days of 90+ weather (something we haven't seen since, but don't take that as a personal challenge, Mother Nature). But five days is stretching it, and six days is nearly unheard of.

Monday's 87-degree high for Seatle marked the 5th straight day at 85 or more in Seattle. In going over the records, we found that hasn't happened since July 23-27 of 1996. I'll have to go back further to find the last 6 straight. The sixth day back then was under 85.

On the other hand, for half of western Washington, the heat wave broke Sunday. In fact, you can draw a line from about Port Townsend southwest to Long Beach. If you're to the west of that line, it's 70 or under. To the east of it, it's well over 80. To wit: Monday evening at 5 p.m., Hoquiam was at 61, Port Angeles was at 65, Everett was at 80, and it was still in the upper 80s in the Seattle area, and 90 in Bremerton and Tacoma.

You can check the high in your area at this link.

It does appear we're going to be sunny and hot once again for Tuesday -- at least for the same areas to the east of that line. Highs should reach the mid-upper 80s in the Puget Sound area, but be at 65-73 to the west of that line. Oh yes, and plenty of sunshine.

So, what's going on? Late last week, we had a thermal trough move up the coast and then move inland on Sunday. Normally, when the winds shift from east to west behind the trough, we get significant cooling as our "natural air conditioning" blows in the cool, marine air inland from the ocean.

However the marine breezes this time don't have much oomph to them. The nightly push of marine air is only making it to about Port Townsend to the north, and the west of Shelton to the south. So, spots to the west of that push are back to the normal 60s and 70s you'd expect for June. But inland, we're still baking.

A second factor is that we have a VERY warm air mass overhead -- so much so that we're into the mid-upper 80s even without our offshore/easterly winds that usually bring our hot air from the air sinking down the Cascades(read more about offshore flow here).

The forecast for the next couple of days does have the marine breezes slowly getting stronger, but they also have the air mass getting even warmer, which will counter-balance the cooling marine effect. So expect another toasty day Tuesday in the I-5 corridor areas.

We do think we'll cool a bit for Wednesday, and then a little more for Thursday. The big cool down looks like it'll occur this weekend, when a strong marine push is expected to drop us back to the upper 60s and low 70s everywhere in western Washington.

In the meantime, if you need to get away from the heat, head to the coast!