4th Wettest “Water Year”

9pm Sunday

October is here and that means we have just wrapped up a “Water Year”.  So what is THAT?

Here’s the deal…our rainy season is late October through March; during the cool season.  As you know, we have a very dry warm season here compared to areas east of the Rockies.  That’s May through September.  All that winter rain and snowmelt is used to sustain our lives/properties/crops through the dry season.  So it’s important to know how wet our rainy season is each year.  But one rainy season crosses from the end of one calendar year into the first part of the next calendar year.  So for the purposes of ranking our wet seasons, we use a “water year”.  That year begins on October 1st and ends September 30th.  Make sense?

This last rainy season was VERY wet.  51.45″ in Portland and of course far more in the mountains.  We typically get around 36-37″ precipitation in the city each year so we gained a solid 15″ more rain than what we’d typically see

This season was the 4th wettest, behind 1996-1997, 1995-1996, & 1955-1956.  The highest on record was 58.67″.  The flooding in February, November, and a bit at the end of December pushed that year into the #1 spot.

Of course last year was a weak “La Nina” year so we expected higher than normal rain, but not THAT much rain!  It’s interesting that the dead of winter (December/January) was drier than normal due to the cold weather.  If we’re down around freezing we’re not getting the usual mild/wet systems coming through.

Snowfall in the Cascades ended up well above average up above 4,000′ and near average at pass elevations.  It’s about what we’d expect in a weak La Nina winter, although note Government Camp just barely reached a “normal” year.  The reason the ski season was so great down low was because the dead of winter was colder than normal and the good snow hit right away in late November and December.

We’ve got lots of sunshine ahead the next few days…this October is looking FAR different from last year’s washout.  We only had 3 dry days the entire month last year plus ZERO clear days.  We’ll easily exceed both of those stats in this first week of the month.

Chief Meteorologist Mark Nelsen


19 Responses to 4th Wettest “Water Year”

  1. Lee Wilson says:

    I can handle clear and cold..lol…better for Solar.

  2. Lee Wilson says:

    Um Mark…you for got the “Ice Scraper Alert”

  3. Jason Hougak says:

    First frost of season

  4. Jason's says:

    First frost of the season. Got to Canby and it was 47F.

  5. Paul D says:

    What makes the water year even more interesting is that we had below normal rainfall Nov-Jan. Oct, Feb & Mar more than made up for it and drove us way above average. Also, Hillsboro was only 8″ over normal – a bit difference compared to PDX’s 15″.

  6. Boydo3 N. Albany says:

    They’re still mowing the lawns at the the Fairbanks campus so I’m thinking we have have no worries for a while…

  7. longviewer says:

    Here in the hills near longview we were 2″ shy of being declared a rain forest! Quite the water year, bot wet and white.

  8. boninepaul says:

    Big thundershower right now in North Portland. Heavy rain and cloud to ground lightning.

  9. W7ENK says:

    Since the radar isn’t working…


    • Joshua Downtown PDX says:

      I barely escaped it. Fun to watch. When I left the office and saw the really dark clouds and felt a few large drops, I knew I had to hustle to cover.

  10. WEATHERDAN says:

    Another Summer behind us. 2017 was the 2nd warmest on record. behind 2015 and ahead of 2014. not a blip as some have said in the past but a growing pattern. Another pattern is the amount of extreme weather along with EPE,s. And now on to Winter. What will it be? Stay tuned. Peace.

  11. Roland Derksen says:

    I think this October will be a lot drier than last year’s. Unlikely though that it will be anywhere near as low as October 2002.

  12. Ellen Wallace says:

    How about possibility of a repeat of last year? Is this another “La Nina” year – weak or otherwise?

  13. W7ENK says:

    65.51″ for the water year here at my place in Milwaukie.

  14. pappoose in scappoose says:

    Makes sense!

%d bloggers like this: