Under the Weather: Halloween 2020 will be dry — and will feature first blue moon since 1944

Photo taken by Randy Small of Whatcom County

This Halloween is poised to be one like no other, with the normal festivities having to be altered or even cancelled due to the COVID-19 pandemic. But for those still venturing out for some safe fun, it is important to keep the weather in mind. In a year that has been anything but ordinary, will the weather actually cooperate?

Using data from Paine Field in Everett, it is possible to see the weather of past Halloweens, including temperatures and amount of precipitation. Below is a graph showing the high and low temperatures for each Halloween since 1998.

If you take an average of these values, the average high temperature on Halloween in our region is about 52.6 degrees, while the average low temperature is about 42.9 degrees. Back in 2006, it got as cold as 29 degrees. Talk about having to layer those costumes!

In terms of rain, 59% of the days had measurable rainfall—meaning that at least 0.01 inches of rain had to be recorded. The record maximum rainfall was a whopping 0.93 inches back in 2012.

This year, we are expecting relatively normal conditions for Halloween. The only exception? It’s supposed to be dry! After some modest rainfall amounts on Friday with the passage of a frontal system (and the potential for a Puget Sound Convergence Zone later in the day), high pressure builds over the area, keeping us dry for most of the weekend. If you are planning on going trick-or-treating in some capacity, this will be music to your ears. Temperatures are expected to be close to average, as well. Despite this, it will still be a bit chilly, so make sure to bring those coats for the kids.

The weather should cooperate enough for us to also view a special astronomical treat—a blue moon. A blue moon is the second of two full moons that occur in the same month. These occur more frequently than the “once in a blue moon” phrase suggests, about every two to three years.

There is something a little extra spooky about a full moon on Halloween, and it does not happen very often. In fact, this will be the first time since 1944 that there was a full moon on Halloween! If the clouds cooperate, we should get a prime view.

A picture of the moon (not full) I took over the summer with my Sony A6000 camera.

Make sure to enjoy the beautiful weather this weekend, while we still have it—models are suggesting the start of another rainy period early next week. I will be monitoring this possibility and update you all as needed.

I hope you all have a great (and safe) Halloween and weekend.

P.S. Do you have any fun Halloween weather stories? I would love to hear them—let me know in the comments below.

— By Kelsie Knowles

Kelsie Knowles is a meteorologist and recent University of Washington graduate who lives in north Lynnwood. After writing weather blogs as a KOMO News intern, she discovered a passion for writing about weather. You can learn more in her blog www.wxnoggin.com and you can also follow her on Twitter at @kels_wx3.


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