There’s a big cool-down coming to Northern California. How much will it rain?
Forecasts earlier in the week promised rain for Northern California, showing a chance of desperately needed rainfall as thousands of firefighters continue to battle numerous major wildfires. But now there’s some bad news.
Precipitation is still expected before the end of the weekend, but it’s now looking more like a brief round of showers at best across the north half of the state, the latest forecasts show.
The National Weather Service anticipates the bulk of the Sacramento Valley and the Bay Area will each get less than one-tenth of an inch in this coming system, with showers starting Saturday and wrapping up early Sunday, according to forecasts issued early Wednesday. Slightly more rain could fall in the northwest corner of the state, and the Redding area could get closer to a quarter-inch.
A major cool-down is still on track for Sacramento, which started October with six straight days in the low- to mid-90s, roughly 10 degrees hotter than normal for this time of year.
Highs will plummet to the mid-70s, with Sacramento forecast to reach between 74 and 77 degrees each day Thursday through Sunday, according to the NWS. It’s expected to warm up slightly after the weekend, with temperatures in the low 80s predicted for next Monday.
The NWS Bay Area office, in an overnight social media post, phrased the latest outlook as a “much drier” storm track than what forecasters previously predicted. On Tuesday, the NWS forecast Sacramento could see as much as a half-inch of rain, and the Santa Rosa area — where the raging Glass Fire has destroyed hundreds of homes and continues to burn actively — could get around a quarter-inch. This earlier forecast had also predicted that rainfall could begin Thursday night or Friday rather than Saturday.
With an astounding 4 million acres scorched through early October, 2020 is already the most severe wildfire season by acreage in recorded California history. Weather experts and fire authorities have noted, in weeks’ worth of forecasts, red flag warnings and daily fire situation reports, the role that critically dry vegetation has played in the persistent wildfire danger.
Even minor rainfall, coupled with much cooler temperatures that are also on the way, should provide some benefit to crews battling existing fires across Northern California. Additionally, it should improve air quality by clearing out some lingering smoke.
But a weekend pass of light showers simply isn’t going to be enough to put a halt to the current wildfire season.
“Will help w/fires & smoke, but will not be season-ending,” UCLA climate scientist Daniel Swain tweeted Tuesday morning, before the NWS downgraded its precipitation forecast totals.
In recent years, many of California’s worst fires — the November 2018 Camp Fire, the October 2017 wine country fires, the December 2017 Thomas Fire in Southern California and last October’s Kincade Fire — have come in the last three months of the year. When there’s a lack of significant, widespread rainfall, those months often mark the intersection of dry vegetation and gusty winds.
This story was originally published October 7, 2020 at 7:51 AM with the headline "There’s a big cool-down coming to Northern California. How much will it rain?."
