After more than six weeks of unusually dry and warm conditions, the Napa Valley is due for cloudy skies and wet weather today.
On Monday afternoon, the National Weather Service was forecasting rain to begin blowing through the North Bay Area on Monday night and increase today. The agency said a thunderstorm and a small amount of hail are also possible.
High temperatures are likely to be in the low 50s and forecasters predicted wind gusts as strong as 18 mph. The heaviest rain should fall from morning until afternoon, but the NWS isn’t forecasting more than a half-inch in most places.
The rain should taper off later today, but it’s predicted to return this week on Thursday and Friday, according to the agency.
Today’s rain is due to a cold weather system moving down from Alaska that will sweep through the North Bay before heading farther south, according to forecasts.
The NWS said last week that the recent dry weather has been due to a high pressure system that’s remained above the area, warding off any potential storms that could have passed through.
In January, Napa State Hospital rainfall gauges recorded 0.34 inches of rain; they had 4.89 inches in January 2012, according to NWS climate data. That’s the driest January on record.
While some Napa residents may be dreading the return of clouds and rainy weather, it’s a welcome development for vineyards in Napa Valley, said Cate Conniff, communications manager for the Napa Valley Vintners trade association.
“From casual conversations, I know the vintners are glad to be seeing some rain this week,” Conniff said. “People are glad to see some saturation in the soil. They’re welcoming the rain.”
The dry weather isn’t causing too much alarm for local grapegrowers because the valley had a particularly wet winter, with major rainstorms blowing through in November and December, Conniff noted.
The vines are also dormant this time of year, she said.
“The vines are still dormant, so it doesn’t have an immediate effect on them,” Conniff said of the recent dry climate.
The dry weather has created a below-average amount of snowfall in the Sierra Nevada, a trend that could lead to trouble if it persists through the next six weeks. The state is projecting it will meet 40 percent of requests for water from the State Water Project this year.
Pat Costello, a water resources analyst for the city of Napa, said last week that the city’s water supply should be fine for 2013, as its reservoirs were filled during last year’s storms. The city also has carry-over supplies from its state water allocations in 2012.