Are Extreme Temperature Events Increasing Rapidly?

My Friday podcast on extreme heat events in the Northwest stirred up a lot of comment and some controversy, so maybe I need a detailed blog that puts the details in front of your eyes.

My baseline is that the maximum temperature, duration and frequency of extreme heat events are Not rapidly growing in the Northwest.

And the mean/average or minimum temperature is increasing faster than the poles.

Let me explain.

First, you must be careful to use reliable observation sites

The Seattle Times and some climate activists love to see the temperatures at Seattle Tacoma Airport, but SeaTac is the FINAL station you want to use for climate research. Why? Because of the airport’s dramatic growth, with the addition of a third runway, many additional buildings, and more concrete. Plus, massive urbanization around the airport. Plus, the observation record only goes back to the late 1940s and the sensor position has been moved.

SeaTac Airport. Weather sensors in the black dot

Based on the recommendation of former Washington State climatologist Mark Albright, let’s take a look at Olympia Airport. No more runways, a much less developed environment (see below), and records date back to 1941.

Below is a chart of the highest temperatures for July and August for the entire record at Olympia.

Do you see a trend in extreme heat? I do not.

There are great years in the earliest part of the record, so if you calculate a linear trendline you’ll get a slight upward tilt (about 1.2F over the period). Again, this is not due to the expansion temperature but rather to the unusually cooler early years on record.

Now let’s look at the trend of the average daily temperature for those months. This is the average of the daily highs and lows. There is more of an uptrend: around 2F over the whole period.

Next, let’s check out another location…in this case Lind 3NE, found in a completely rural area east of Washington (see surrounding image below). This station dates back to 1931. There is no urbanization here. An area of ​​arid natural or cultivated soil conditions.

This is a chart of the annual maximum temperatures in Lind. Mama Mia! The extremes are DOWNWARD. The warmest years soon hit records.

Well-contacted observation sites, mostly rural, also showed similar behaviour. In contrast, highly urbanized or disturbed locations (such as SeaTac), especially those with sensor exposure problems, showed a greater tendency for temperatures to rise. Clearly, these observations do not suggest an existential threat … just a small upward trend in mean temperatures and less of an increase in extreme warmth.

Six-day heat wave

A lot has been made in the press and by some climate activists about the SeaTac reaching six days above 90F for the first time. This kind of frequency above this threshold can be very deceiving, as very small warming (eg .1 F) can cause a frequency to cross the threshold.

It makes much more sense to look at actual temperatures for the six warmest days per year.

So let’s do it!

For Seattle, six warm days last week ranked third in record time. Note that many other years were right behind. And remember all the recent man-made warming caused by the third runway and beyond. Without all that growth, last week’s SeaTac temperatures would have been much lower on the list.

As for Olympia, last week fell to fifth, and was two degrees colder than the “winner” in 1981. 1941 was also warmer.

It was very warm in eastern Washington last week, so what about Lind (see below)? Last week’s heatwave didn’t even make the top 10.

Were we unusually warm for a long time last week? You bet. Does global warming contribute to it? Quite possibly in a few degrees. Is this a record six-day warm period at any lookout in the region? No.

Some people are concerned when I put our summer heatwaves in historical perspective, but it’s important to do so. Heat waves are nothing new in the Northwest. Although our average temperature is rising slowly, the poles are rising more slowly. And when it comes to impacts, the extremes are really what counts.