If you've been watching over the past few days, it's probably no big surprise that it's been hot...and will be hot for one more day! What's so amazing about this hot weather, though, really isn't revealed until you look into the little details.

First, let's look at just how much temperatures have gone up - and down - in one day. I'll use Hillsboro because it's the best example. Yesterday morning the temperature bottomed out at 46 degrees - 46! And by afternoon it warmed to 93. That's nearly a 50-degree temperature swing in about twelve hours...pretty amazing. But that's not all.

The temperature swings that took place from hour to hour were pretty impressive, too. In Portland yesterday at 11am, the temperature checked in at 74. By noon it shot up to 86. Twelve degrees warmer in one hour! What happened in that one hour to push the temperature up so quickly? Our winds switched to an easterly direction.

To look at those hourly weather observations, click here.

I talked about it in my Monday blog - the quick overview is that easterly breezes have been descending the windward side of the Cascades, and as they do so they heat up. So all that heated air just surges right into the region. It's a front of sorts- and behind it, hot and dry air lurks.

So between 11am and noon yesterday, that front arrived, and the hot air pushed in.

But all this is about to change. The huge upper-level ridge of high pressure that has given us this warm weather is going to start breaking down...and cooler Pacific air will begin oozing in. Chances are, this will be the last 90-degree day we'll see until next summer. So if you like the warm sun - enjoy!

Joe M.