Do Sonoma County’s big October rains mean a wet winter’s on tap?

Santa Rosa enjoyed the second-wettest October on record, fueling hope that the North Coast’s rainy season will again spare the region from falling back into drought.

The city had accumulated 7.35 inches of rain as of 10 p.m. Sunday, enough to shatter the second-place total of 6.44 inches for the month of October set in 1975.

More rain was on tap for Santa Rosa Monday night, putting a damper on trick-or-treating. However, forecasters said the precipitation was unlikely to push Santa Rosa above the all-time record for wettest October - 9.47 inches recorded in 1962.

Nevertheless, water resource managers remain hopeful that the early rainfall bodes well for a wet winter.

“We’ve got the soils primed for action in terms of allowing runoff into the reservoirs,” said Brad Sherwood, a spokesman for the Sonoma County Water Agency. “And it’s a good sign for having a productive winter.”

The National Weather Service has gone back and forth predicting whether this will be a La Niña type of winter. The agency now places those odds at 70 percent. Such a weather pattern, in which sea surface temperatures are colder than normal, could mean colder and wetter conditions than average for Northern California. Already, snow blankets some Tahoe peaks at the highest elevations.

Closer to home, Lake Sonoma, the region’s largest reservoir, is currently at 86.1 percent of its water-supply capacity, while Lake Mendocino is at 89 percent of its maximum water supply level. For Mendocino, that’s just shy of the 25-year average of 90.2 percent capacity for this time of year, and for Sonoma, above the average 81.4 percent, according to the water agency.

Sherwood cautioned that a wet autumn is no guarantee that the trend will continue into winter and spring, when the timing of storms is crucial to maintaining reservoir levels.

He pointed to winter 2013, when the North Coast from the southwest corner of Sonoma County to the Oregon border received just ?12.6 inches of rain from December through February after a promising start. It was the region’s third-driest winter in history.

That winter, less than an inch of rain fell in December and January in Santa Rosa. The average total for December, January and February is 18.14 inches.

Last year, a series of “atmospheric rivers” - narrow, intense plumes of moisture - dumped ?23.74 inches of rain in the Santa Rosa basin from ?Oct. 1 through early March, along with 28.55 inches in the Ukiah basin, both within an inch of average for the date.

The rains also filled reservoirs to capacity and helped bring the North Coast officially out of severe drought.

Most of the North Coast, including Marin County and virtually all of Sonoma County, is now classified as abnormally dry, the mildest of the five categories issued by the United States Drought Monitor, a consortium of government climate experts.

Statewide, roughly ?60 percent of California remains in a severe, extreme or exceptional drought, mostly in Central and Southern California, according to the drought monitor.

As much as another inch of rain was expected to fall in Santa Rosa Monday into early this morning.

The forecast calls for dry conditions for the rest of the week.