What's with all the single-digit low temperature records?
Want to know something unique about this coming weekend? It'll be two days (Jan. 26 and 27) whose record lows weren't set in 1950.
If you were wondering with our cold snap last week with lows down into the low-mid 20s why we weren't even in the same zip code as the record lows, you can thank one amazingly cold winter that has set dozens of low temperature records likely out of reach for ages, if not maybe forever.
The 34-day period between Jan. 1 and Feb. 3 had four incredible arctic blasts that crippled the city with several inches of snow and days upon days of bone-chilling temperatures that dropped to single digits overnight.
In fact, 18 of the 34 low temperature records from that time are from 1950 --12 of them in single digits, including the Holy Grail of our cold records, the 0 degree reading on Jan. 31. That stands as the coldest day ever recorded at any official Seattle reading, be it Sea-Tac Airport or the Downtown Federal Building, which kept records from 1891 through 1972.
The average temperature in January was 24.85 degrees and, you guessed it, the record for coldest January on record.
Not even close since then?
Aside from that winter, single digits have been quite rare in Seattle throughout our history. Current low temperature records show just seven other dates with a single digit record low* -- a 9 degree reading on Jan. 26, 1957, a 7 degree reading on Feb. 4, 1989 (the most recent single digit reading), a 9 and 6 degree reading on Nov. 14-15 in 1955, a 9 degree reading on Dec. 23, 1983 and an 8 and 6 degree reading on Dec 29-30 in 1968. There are a couple other single digit recordings that are not current record lows but not many.
(*There is also officially a record low of 2 degrees on Feb. 26, 1951 but I don't believe that it's accurate. It's emblazoned in the Seattle record books for that day, but the day before had a low of 29 and the day after had a low of 25 so this makes me think there is a second digit missing when getting entered in the climate record like "20" or "22" and it's just stuck since. Olympia had a low of 9 that morning; Bellingham 19. Even the Downtown Federal Building, which recorded data then, reports a record low of 24 on that date and it's not for that year (1962) which means it was 24 or warmer there in 1951.)
Part of this will be the urban heating effect -- now that Seattle is a much larger city, it creates its own heat a bit and all the buildings and blacktop and asphalt hold in nighttime temperatures better. So what might have given a low of 8 in 1955 might only give a low of 13-15 today. 1990's infamous arctic outbreak "only" got down to 12 in Seattle. Our 2008 extended snow event "only" got down to 14.
So it's going to take something truly historical before 1950's records ever feel threatened again.
By the way, if you want more information on the specifics of the storms, there are two past blogs you might be interested in:
This one goes into general detail about the storms and their impact on Seattle.
And then there is this blog I wrote last January with greater details on each individual storm, courtesy of a treasure trove of articles saved from the Bellingham Herald by the Albright family.
And in case you're curious, the warmest record low in January is 19 - Jan 7, 1973.
1950, Day by Day
Here is the day-by-day chart of January and February's weather at Sea-Tac Airport. (Dates higlighted in blue are still current record lows.)