Do San Juan Islands *really* get 247 days of sunshine a year? I'd love
to see some proof.

I am moving to Seattle and am intrigued by the oft-repeated statistic
of "247 days of sunshine used to promote the San Juan Islands.

These links (see sunshine charts) seem to contradict the claim:

http://www.city-data.com/city/Friday-Harbor-Washington.html
http://www.city-data.com/city/Seattle-Washington.html

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Request for Question Clarification by tutuzdad-ga on 09 Mar 2006 09:22 PST

Well, what you heard is true but the truth is that the San Juan
Islands enjoy an AVERAGE of 247 days of sunshine and half the rainfall
of Seattle. This is due to a phenomenon known as the "rain shadow"
effect caused by the Olympic Mountains to the south. The rain shadow
effect is the result of the process by which moist air on the windward
side of a mountain rises and cools, causing precipitation and leaving
the leeward side of the mountain dry. These sources may help to
explain it better.

RAIN SHADOW EFFECT
http://www.weatherpages.com/rainshadow/

NATIONAL PARK SERVICE
http://www.nps.gov/sajh/pphtml/subenvironmentalfactors21.html

Please let me know if this suffices as "proof".

tutuzdad-ga

"247 days of sunshine a year" means that the sun shines sometime on
that many days, not that the weather is like in sunny Southern
California.
If you check out the sunshine graph for Friday Harbor you will see
that it gets less sun than the US average, and the cloud chart
indicates that there is a fair - maybe, unfair - amount of such.