Cool temps, high humidity. Will this help prevent wildfires?


PORTLAND, Ore. (KOIN) – You may have summer on your mind, I don’t blame you. June 20 is the official start to summer, but we know that it doesn’t just change over that moment.

We have already had brief stints of summer, going back to May. There were eight 80 degree days in May, with two back-to-back days in June where we hit 90 degrees or more. It has definitely felt like summer more than once around here this spring.

The counterbalance to that? How about a week that is slightly cool and wet. It won’t be enough to combat our drought, but it will feel more so like a traditional spring week. We remain cool Monday through Friday, with high temperatures below average, floating in the upper 60s.

A spotty shower here or there should help bring some raindrops to the spring flowers that are around. Expectations may feel high this week, with great hope for some measurable rain around here. Like most expectations, the reality doesn’t always match up. Although we are sitting in a trough of cooler air, measurable rain is still going to be hard to achieve.

Check out the weekly rain chance this week:

It’s clear that even though it looks like it may rain outside, the deep moisture isn’t here and the valley is missing out on the good stuff: water. With that in mind, there have been a few locations that may see some rain this week, and that is the northwest Oregon coast. Astoria is currently a quarter-inch above the average at this point in time. That’s not saying much in the grand scheme, especially since we have plenty of June to go, but it hasn’t happened in months. We’ve been dry from the coast to all bordering states.

If you look at the satellite loop below, you will notice one thing, there is a lot going on around here. That is a sign of possibility! We have a broad upper-level trough over the region which is maximizing our opportunity for shower development. If you look really close, you may even see the signs of small-scale disturbance spiraling west of Washington and Oregon.


You may not have realized this, but you could probably deduce, that our top wettest days this year have all come in January and February. It’s not uncommon for the winter to bring in hefty rain totals, but it is also not uncommon for our spring months to bring in some loaded rain events. This year it has been rare.

One thing you may not have realized is that those days that are on our list above, aren’t that wet (outside of Jan. 12). We’ve only had one day this year that has cracked one inch of rain. It looks like we will have to rely on the upcoming fall months to play catchup, which is never promised. There have been seven days this year that we have had half an inch of rain or more in 24 hours. Our yearly average is 18, which again means, we will have to count on the fall months to see that number increase.


Our wettest day in the meteorological spring months of March, April and May is a whopping quarter inch on March 7 (technically still winter). A few weak atmospheric rivers to show, but the rain in the valley was dismal. You can see the wettest days so far, by month, in the graphic below. It’s hard to believe that we have to hold some pride on a quarter inch of rain, but it is honestly the best we’ve done. Most systems that have decided to sweep through the valley have been astonishingly weak. That is exactly the story at hand this week. It seems like most rain events bring in less than one tenth of an inch in Portland, which is just not enough.



Wind and Humidity Observations NWS 6.7.2021 Morning

Although the soaking spring rains haven’t showed up, this week is still beneficial because of the cool temperatures and high humidity. If we aren’t going to pick up rain, we at least want the temperatures to remain low and the humidity levels to be high. When the temperatures warm up the relative humidity will drop, which aids to the progression of wildfires. Relative humidity is a gauge for how dry it may be, but mostly for the process for a moisture trade off between our atmosphere and the fuels. In the graphic above, you will notice in the green text, the humidity percentage at that location. When those numbers are in the teens or lower 20s, that is when conditions are not in our best interest. Of course we need rain, but if we can at least keep the cooler weather and high humidity levels, that ultimate is a helping hand.

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