Normally February is our second wettest month of the year, second only to January, with almost 4 inches of rain. This February we had .48 inches, or about an eighth the normal amount. Yet the year has been so dry so far that even so February was our second wettest month.
In strong El Niño years February is our wettest month with about 9½ inches. We got about a 20th of that amount.
From 1 Sept we have received 7.66 inches, the historical average for this period is 13.37. We’re at about 57% of normal. The average for strong El Niño years is 24.59 inches. We’re less than a third of that.
We’ve received less rain this year than last. We’ve received less rain this February than last.
That may change. Some long term predictions suggest we’ll have a wet March, that the high pressure ridge (the Martin ridge) that keeps the storms from Southern California is finally breaking up. Indeed the weather forecast shows a series of storms hitting us next week.
It’s probably too late to hope for a rainy year. We’re currently down 5.71 inches from normal, if we’d like to get up to normal rainfall by the end of the month then we need that much rain, plus what we normally get in March, or 8.67 inches total.
We have approximately 150 years of rainfall data for downtown SB, and we’ve gotten that much (or more) rain in March a total of nine years in the past, and in two of those (1912, 1991) they had received even less rain to this point in the year than we have.
So it is possible.
Interestingly enough none of those years was a strong El Niño year. Two of them were “weak” El Niño years and a third was neither El Niño nor La Niña. (the others occurred before we were able to take the measurements currently used to classify a year as El Niño or not).
The strong El Niño years have averaged 3.6 inches in March, only marginally more than the historical average of 2.96 inches.
Given that this is a “very strong” El Niño year, the historical precedents suggest we will not even get up to normal rainfall for the year.
Looking at this year (so far) and the last two, Mother Nature appears to be running a rather interesting experiment. This year we got a lot of rain in January and the rest of the year has been dry. Last year we got a lot of rain in December and the rest of the year was dry. The year before that the rain came at the end of February/early March and the rest of the year was dry.
In other words we can compare these three years to see how the plants react to a single spurt of rain in either Dec, Jan or Feb.
For most plants it’s too early to tell (for this year anyway), but bigpod ceanothus has already been affected. This is the species that covers our hillsides in a blanket of white in early February, so it’s a very common, and obvious species.
In a normal year bigpods start blooming in late December and bloom into April with a peak in February. This year (January rains) they started blooming in early February, never really peaked, and are almost gone already. Last year (December rains) they started in December, as usual, peaked as usual, but faded fast and were gone by the end of February. Two years ago (February rains) they started in early January and fizzled out in February, but about three weeks after the rain they started blooming again — they never reached a peak were they covered the hills though.
So it looks to me as if bigpod (at least) needs significant rain in December to have a February peak where the hillsides are white.