Hot at Night?

If you had trouble sleeping last month, no wonder.

At 59.9 degrees, the average low temperature in August was the highest of any month in Seattle since record-keeping began back in 1891—smack-dab in the middle of Benjamin Harrison’s presidency. Simply put, no month has ever been warmer at night than last month was.

In other words, if Arthur Denny had founded Seattle in August 2013, we’d all have air conditioning.

What’s really remarkable about last August is that the low temperature only fell below average once—on the first day of the month, dipping to a “cool” 56 degrees. (The average that day was 57.) 29 of the remaining 30 days saw above normal lows, with the other day—Aug. 6—matching the typical low of 57. In the end, the month wound up with an average low temperature exactly 4 degrees above the norm of 55.9—blowing by previous records of 58.4 degrees at Sea-Tac Airport (August 1967) and 59.1 degrees at the Federal Building in downtown Seattle (July 1941).

Seattle will rotate between clouds and sun this week, with continued warm nights. A greater chance of rain arrives Thursday.
Seattle will rotate between clouds and sun this week, with continued warm nights. A greater chance of rain arrives Thursday.

Although the calendar now reads September, we’ll continue with our trend of warm nights the next several days as a lack of true marine air holds overnight lows near 60 degrees. (The average for this time of year is 55.) In addition, another upper level low spinning off the coast will keep things somewhat cloudy at night, preventing temperatures from dropping off too far.

What about highs? Today will actually be the warmest of the bunch, with the mercury again threatening 80 degrees under blazing blue skies. For tomorrow, increasingly cloudy skies will knock temperatures back a few degrees into the mid 70s—in line with the early September average of 74. There could even be a few showers as far east as Olympia, but most of the action will remain near the coast.

We stay in the mid 70s for Tuesday and Wednesday with scattered showers dotting the region—particularly over the mountains, where some thunderstorms could touch off a couple brief downpours. Overall, both days should be more dry than wet, with conditions alternating between partly sunny and mostly cloudy.

On Thursday, the upper level low starts to wander ashore, tracking inland somewhere between Seattle and Eugene. If the low barges in to our south, we could see a pretty wet day, with heavy showers and thunderstorms raking the region—similar to the 0.76” pounding we took last Thursday. A further northward track would result in lighter rainfall for the area.

Either way, there’s one thing you can bank on: it’ll be balmy at night.

Keep those windows open.