It's so unusual in this season of endless drought, we have to mention it: Streets, sidewalks and parking lots in San Francisco and across the parched Bay Area have been moistened overnight by a precipitated substance very much like rain.

In fact, the National Weather Service's Bay Area office reports that rainfall has been recorded in seven of the nine Bay Area counties, from Poverty Ridge, east of San Jose in Santa Clara County, to Chalk Mountain, north of Santa Rosa in Sonoma County. The only counties with no rain reports are the region's northeasternmost, Napa and Solano.

The highest precipitation totals for the 12 hours through 8 a.m. Thursday were .12 of an inch at Tilden Park in the Berkeley Hills, with an identical total recorded at an official weather station in the closely associated Oakland Hills. locations in the Berkeley and Oakland Hills.

The weather service forecasts a 20 percent chance of rain throughout the Bay Area for the rest of the day Thursday, and says the cloudy, cool conditions we've been seeing -- and rain chances -- will persist through Friday. We're supposed to see some clearing and a slight warmup over the weekend.