San Francisco has experienced over the past two rainfall seasons nearly the driest weather in 170 years, according to Golden Gate Weather Services, which provides consulting meteorological services.

Just 20.46 inches of rain fell over the two rainfall seasons from 2019-21, second only to the 1975-77 period when just 18.53 inches fell.

The 20.46 inches is 45 percent of the normal amount, which is about 45 inches.

“It has been two very dry wet seasons back-to-back,” National Weather Service meteorologist Drew Peterson said.

Around the Bay Area, the total amount of rain this past season ranges from 39 to 41 percent of normal. Downtown San Francisco received 8.76 inches of rain, just 41 percent of normal, while 39 percent of normal fell at San Francisco International Airport.

Peterson said generally California has two to three years of rainy weather and two to three years of dry weather.

“This is a very boom or bust state,” Peterson said.

In the Monterey Bay Area, it has been a bit wetter, thanks to two recent atmospheric rivers which brought rain to that region and missed most of the San Francisco Bay Area, he said.