A mild storm this weekend could nudge away the fog that has beset the area for much of January.
But the fog could be back early Monday, the National Weather Service predicted, so drivers should watch out on the roads.
Rain has been sparse for most of this month, after a very wet start to the winter. The Modesto Irrigation District reported 7.79 inches at its downtown headquarters as of Jan. 11 but just 0.9 inches since then.
As of Jan. 6, the snowpack in the central Sierra Nevada was 173 percent of average, according to the California Department of Water Resources. The figure dropped to 126 percent as of Friday.
The central Sierra supplies most of the water used by farms in the Northern San Joaquin Valley, and part of the city water.
More storms from now through early spring are needed to keep the year from slipping to below average.
Water managers note that the weather this year has been influenced by La Niña, a cooling of equatorial Pacific Ocean waters. It has been known to bring wet starts to winter, followed by dry months.
"We are still optimistic for a good water supply but realize that we can come up short any given year," water resources director Mark Cowin said in a news release Friday. "Our unpredictable weather and delivery restrictions make it clear that conservation must always be one of our top priorities."
The National Weather Service forecast a 20 percent chance of rain in Modesto after 10 p.m. today and a 50 percent chance Sunday morning and afternoon.
Snow is expected above Twain Harte on Highway 108 and near the Yosemite National Park gate on Highway 120. Travelers in the mountains should carry chains.
Areas of valley fog are expected Monday through at least Thursday. It tends to develop when the ground is moist and wind is light.
Bee staff writer John Holland can be reached at email@example.com or 578-2385.