It might actually rain

The National Weather Service predicts that it might actually, finally, possibly rain in San Francisco over the next few days, a spectacle not seen in the city since the spring.

The latest forecast calls for “drizzle” on Friday and Saturday night, a “chance of showers” (around 20 percent) on Monday morning and then a stronger change of rain on Monday night and Tuesday.

It’s not much to work with, but other forecasts, such as the Weather Channel’s Weather.com site, agree, putting the chances of rainfall on Tuesday around 40 percent.

According to the NWS archives, San Francisco has recorded zero precipitation since the end of April.

That’s low (of course), but according to the weather site Intellicast these months are rarely rainy anyway; the historic SF average for May through September is at most 0.54 inches, with July averaging just 0.04 inches most years.

The historic rainy season lasts from November through March, with the heaviest rainfalls usually in January, which holds a historic average of 4.72 inches.

In 2018 SF saw 4.85 inches in January, an alarmingly dry February (just 0.39 inches) and then a more or less average spring.

The U.S. Drought Monitor assesses Bay Area conditions as “abnormally dry” as of this week, though less so than much of the rest of the state, 47.94 percent of which is in some state of drought, with “extreme drought” in 4.97 percent of the state (that area concentrated in the far southeastern portion).

• SF Forecast [NWS]
• SF Weather Data [NWS]
• Local SF Averages [Intellicast]
• SF Forecast [Weather.com]
• California Drought Map [US Drought Monitor]