August is prime time for summer vacations, but probably the most notable vacation was Seattle's rainfall, which ended up taking the entire month off.
The month finished with just a trace of rainfall -- the first time in the history of Sea-Tac Airport that August went with no measurable rain. The old record was 0.01" in 1974.
The upshot of the dry month was our still-alive streak of consecutive days without measurable rain -- up to 43 days through Monday and now third-longest.
Temperature wise, it was the first month since May that was above normal, finishing with an average high temperature of 78.5 degrees -- good for sixth warmest on record. It was capped off by two brief heat waves that saw the temperature cross 90 degrees a total of four times. First up was a pair of 93 degree days on Aug. 4-5 over SeaFair's hydro and Blue Angels weekend (the 93 degree temp on Aug. 5 made it the second-warmest hydro race on Lake Washington in Seattle's history.)
It was then followed by a week-long stretch of 80s that included two days of 87, an 88 then capped off with a 94 and 91 on the 16th and 17th. The 17th was the last date in the 80s, but the following two-week stretch of highs in the 70s to finish off the month didn't have anyone complaining. In fact, it was only the third time in Seattle history that August didn't have a high temperature cooler than 70. Who'd a thought after such a chilly, gloomy June and July?
The 30 day forecast indicates much of the same, going with higher than average chance of a cooler but drier September -- just like it has for July and August, of which it's batting 50-50. But dry and warm weather is the rule for the first part of the month.
September is though when we begin our rapid transition from summer to fall. August is quite dry. October 1 is the official start of the rainy season. The average high temperature is 74.3 on Sept. 1., but on Sept. 30, it's down to 65.7 degrees. Sept. 2's record high is 99; Sept. 21 is the latest 90-degree day on record.
At the start of the month, any day has on average about a 23 percent chance of rain. By the end of the month, it's up to 35 percent.
Suffice to say, if March comes in like a lion and out like a lamb, September is the exact opposite.
|Sea-Tac Airport Stats||August Average||August Observed||September Average|
|No. of days with Rain||6||0||9|
|No. of Sunny days (0-30% clouds)||9||12||8|
|No. or Partly sunny days||10||17||9|
|No. of Cloudy Days.||12||2||13|