April 03, 2017

The First 60 Degree Day of the Year in Western Washington

There are all kinds of weather records, but one of great importance to residents of sun-starved western Washington is the first 60F day of the year.

What is so special about 60F?  Perhaps because with some sun, this temperature is warm enough that one is comfortable outside without a sweater or jacket.  Whatever the reason, after a cold late winter and spring, Seattle-Tacoma Airport has yet to hit 60F.  In fact, we are getting close to a record--the latest into the spring that Seattle has hit 60F.   Not the kind of record one likes to break.

When was the latest time Seattle hit 60F?  As shown below, early November, 5 months ago.

Below are the ten latest 60F dates at Seattle Tacoma Airport (whose observations extend back to the late 1940s).   The worst year (latest 60F) was 1954 with April 11th.   Now the first day we could hit the big 6-0 this year is Tuesday (April 4th), so we will at least be tied for 4th place with 1950/51.

So when will we reach 60F?  Weather.com is suggesting we will just make it  on Tuesday:

The ultra-high resolution (1.3 km) UW WRF model is going for 60-64F (medium red color) over much of Puget Sound at 5 PM on Tuesday:

As I have noted many times, it is important to forecast probabilistically using an ensemble of many forecasts, since all weather predictions have uncertainty.  The fabled European Center ensemble forecasting system suggests that average of the ensemble members (black line) just reaches 60F on Tuesday, with a range of temperatures from 56 to 64.   Roughly a 50% chance of reaching 60F that day.

 How about the National Weather Service Short Range Ensemble Forecasting System (SREF)? Barely reaches 60F on Tuesday, with a much better change on Wednesday.

So we have a real shot at it on Tuesday....keep your fingers crossed.   If we miss 60F on Tuesday we have a chance of beating the big record with 60F being reached after April 11th.


Help Determine Local Impacts of Climate Change
Society needs to know the regional impacts of climate change and a group at the UW is trying to provide this information with state-of-the-art high resolution climate modeling.  With Federal funding collapsing, we are experimenting with a community funding approach.  If you want more information or are interested in helping, please go here.  The full link is: https://uw.useed.net/projects/822/home


  1. My money is on not hitting 60 here in the south Sound this week.

  2. Sunday in the Skagit Valley, fields of daffodils, tulips still hiding. 60 degree days will switch on the color.

  3. The first 60 degree day of the year for Western Washington has already been reached. In Olympia, at KOLM, the temperature reached 60 degrees on April 1; not sure if it reached 60 degrees earlier in other parts of Western Washington. Maybe you meant the first 60 degree day of the year for SEATAC or Seattle?

  4. How will we know if we got there today or not? It seems that some weather stations (for example Renton) may have passed the 60-degree mark, but it appears the SeaTac station may not have. Can you give us an update later today (Tuesday the 4th)?

  5. On February 15, BLI measured 61F. My PWS, located about 1.5 miles southeast, reached 60F. Today, my PWS measured 60F for the first time since, though BLI appears to have only reached 58F.

  6. Don't know if this is hotter than 60 degrees,
    but as Cliff mentioned a bill is in motion
    to improve weather forecasts
    and is hitting the president's desk.



Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

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