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Chilly Northwest summer? It may all be in your mind

Some people feel it hasn't been much of a summer around western Washington, but the numbers tell a different story.

SEATTLE — People have complained about this being a chilly summer. There have been some chilly and wet days. But is this summer warmer or colder compared to most?

Turns out western Washington has actually been warmer than normal for high, low, and mean daily temperatures.

We keep track of each day's high, low and average temperature at Sea-Tac Airport, which is where our main climatological site is located. Generally, the high temperature in summer is more a measure of how "summery" a day may feel. 

In July, we had 15 days with above-normal high temperatures, 12 below-average high temperature days, and two days right on the 30-year normal. This is a pretty even split.

Credit: KING 5 Weather

August was a slightly warmer-than-average month with 17 days of above-normal high temperatures, 11 days below normal, and three days of normal temperatures.

Credit: KING 5 Weather

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This is what you would expect from a "normal" summer. This may seem strange, but that's because we use the term "normal" when we really mean "average." Some days are above and some days are below, bringing us to the average. But the "average" or "normal" seldom actually occurs. 

But how do July and August 2019 compare to the monthly averages over the past 30 years (the measure of "normal" for the National Weather Service)?  You can see that both months have actually been warmer than the normal. July's high temperature was just 0.7 degrees warmer than usual, but August's high temperature was 2 degrees warmer.

Credit: weather
Credit: KING 5 Weather

How can this be when it seems so cloudy and cool to some people? It may be that we are having much warmer-than-average summers more often. People's expectations have shifted to expect more sun and warmth as the "normal."

The big difference was the average low temperature. There has been a real trend in the last 10 years to have warmer low temperatures in August. Based on average low temperatures, seven out of the 10 warmest Augusts have occurred in the last seven years.

Based on monthly average high temperatures for the past 30 years, last summer was the warmest July recorded at Sea-Tac and the 12th warmest August. This recent tendency to warmer summer months is apparent. Listing the warmest months recorded in the past 30 years at Sea-Tac, you can see 12 out 15 of these have occurred in the past 10 years.

So it maybe we are just adjusting our expectations to the changing climate.