May Rain


It rained last night in our part of the Bay Area. Not a lot–just enough to sort of wet everything down and leave water beaded everywhere on foliage this morning (like the neighbor’s parking-strip apple tree). In most of the country, rain in May would not be news. Here it’s rare, but not unheard of. As Jan Null, a local meteorologist who has pored over San Francisco’s precipitation history, told his email list over the weekend:

Rain in San Francisco at some point during the Memorial Day* weekend has occured on 34 occasions (21% of the the time) in the 163 years since rainfall records began in San Francisco in 1850. Rain has fallen on Saturday 15 times (9%), Sunday 23 times (14%) and on Monday 16 times (10%).

The last time there was rain at any point on a Memorial Day weekend was Sat., May 28, 2011, when 0.28 inches fell. The last time rain fall on the Monday of Memorial Day weekend was in 1993 when 0.01 inches fell. And the last time there was rain on all three days of the weekend was in 1932 with 0,26, 0.18 and 0.10 for a total of 0,54 inches.

The rainiest Memorial Day weekend was 1906 with a total of 1.64 inches, and the rainiest single day of a Memorial Day weekend was Sunday, May 27, 1990 with 1.42 inches.

* Formerly known as Decoration Day dating back to the Civil War.

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