In general, our concepts of things like 100 Year Floods and 1000 Year Floods are based on what we have measurements for, which is usually roughly the 20th Century. But it’s quite possible that the 20th Century wasn’t all that representative. Perhaps the 21st Century will be quite a bit more extreme in one way or another.
Here’s another Old Weird California weather fact. Richard Henry Dana visited California on a sailing ship out of Boston in the mid-1830s and came back to write an 1840 bestseller about it, Two Years Before the Mast.
One of the themes of his book was the trouble caused by a routine cold wind out of the east which blew his ship away from the California coast almost to Hawaii. Back then, it had a name and was considered by Californios to be a common pest.
“There was a desert wind blowing that night. It was one of those hot dry Santa Anas that come down through the mountain passes and curl your hair and make your nerves jump and your skin itch. On nights like that every booze party ends in a fight. Meek little wives feel the edge of the carving knife and study their husbands’ necks. Anything can happen. You can even get a full glass of beer at a cocktail lounge.”
But, apparently, there used to be a cold wind from the East in Southern California. Yet, when Dana revisited California just before the Civil War, he mentioned that the cold East wind had stopped, which had made life much more pleasant in California.