Does Tri-Cities really have 300 sunny days a year? See sunshine tally for 2025
When you tell someone you’re from Washington state, they often think of Seattle and constant rain.
Many people forget — or don’t realize — that there are massive differences between eastern and western Washington, both in climate and culture.
The east side of the Evergreen State has much colder winters and warmer summers than the west.
Misconceptions about Washington may have been a motivating factor in the push to brand Tri-Cities as having 300 sunny days per year. Over the years, the claim has been used by many local organizations to attract people to the area.
How sunny is Tri-Cities, really? Here’s what to know:
Does Tri-Cities really see 300 sunny days a year?
The assertion that Tri-Cities sees 300 sunny days a year has been attributed to different organizations over time — although no one has officially taken credit for the claim.
It’s been repeated by local chambers of commerce, Visit Tri-Cities, the Tri-Cities Airport and the Tri-Cities Development Council, even the Washington State Department of Commerce.
That sunny day count may be the work of a now-retired Visit Tri-Cities president, numerous sources say.
Julie Woodward, vice president of marketing at Visit Tri-Cities, previously told the Tri-City Herald that she “believed” that was true, but could not offer verification either way.
Visit Tri-Cities seeks to attract Northwest tourists to the region, making the weather a major selling point.
The local tourism organization often says Tri-Cities has the “best weather in the state,” hoping to attract folks from Western Washington eager to avoid rainy skies.
“The largest percentage of our visitors come from Seattle,” Woodward told the Herald via email in 2024. “They are looking for an escape from the rain and gray and seeking sunshine.”
What counts as a sunny day in Tri-Cities?
To be considered a “sunny day,” the sky must be clear during regular observation hours — but it doesn’t have to be free of clouds for a long period of time, according to numerous sources.
Following this criteria, Tri-Cities may have an average of 300 sunny days per year.
However, Pasco resident Jim Zimmerlin feels this definition was misleading, even counter-intuitive.
“This was obviously horrible methodology, so I set out to keep my own records of how many sunny days we had, using what I felt was a much better criteria,” Zimmerlin told the Herald via email in Janguary.
Zimmerlin requires a day to have more hours of sunshine than hours of cloudiness in order to be considered a sunny day. If a majority of hours between sunrise and sunset show sunshine, that’s a sunny day.
He’s kept up the daily practice of tracking sunshine from his Pasco home for several years.
How many sunny days did Tri-Cities have in 2025?
Zimmerlin counted 233 sunny days in Tri-Cities in 2025.
“It was our sunniest year since I started measuring three years ago,” Zimmerlin told the Herald.
In comparison, he counted 213 sunny days in Tri-Cities in 2024. The year before, the region had 195 days of sunshine.
Zimmerlin sent the Herald a breakdown of how many sunny days he recorded each month in 2025:
- January: 17 sunny days
- February: 8
- March: 12
- April: 26
- May: 27
- June: 29
- July: 26
- August: 25
- September: 22
- October: 19
- November: 11
- December: 11
Zimmerlin said January and December were much sunnier in 2025 than in previous years.
“In both 2023 and 2024, those were very cloudy months,” Zimmerlin said. “But we got lucky in 2025!”
In January 2025, Tri-Cities had 17 sunny days.
In comparison, the region saw only eight sunny days in January 2023 and just four days of sunshine in January 2024.
In December 2025, there were 11 sunny days in Tri-Cities, compared to three in December 2023 and six in December 2024.
How does one local determine sunny days in Tri-Cities?
To Zimmerlin, it’s important to consider people’s impression of what makes a sunny day, saying he wants to report a number most people would agree with.
Most days, he said, it’s an easy call to make.
On average, there are generally only about five days a year when it’s difficult to determine whether a day could be considered sunny, given fairly equal cloudy and sunny hours, Zimmerlin told the Herald.
“On the few where it’s a bit of a toss-up … I go with optimism and call it a sunny day, since we are still talking about something like six hours of definite sunshine that day,” Zimmerlin said.
That leaves him with a reliable confidence factor of 360 of 365 days, “or 92%,” he said.