This month will go down as one of Portland’s wettest Septembers on record.

Just how wet has yet to be determined.

Monthly rainfall at the airport totaled 3.5 inches as of midnight. But overnight rain drenched the city, unofficially adding .29 inches to the total as of 7 a.m.

That’s already enough rain for the sixth-highest September since record-keeping began at the airport in 1940.

Portland’s rain total was aided, in part, by a thunderstorm Saturday with very scary skies and lots of social media posts.

Depending on what happens the rest of Sunday and on Monday, this month could crack the top 5. The forecast calls for up to a tenth of an inch today, although that could be higher depending on the location of potential thunderstorms.

“We definitely have a legitimate shot at getting into the top five,” said Colby Neuman, a meteorologist at the National Weather Service in Portland.

Fifth place on the list of rainy Septembers is 1969, with 3.86 inches. Second is 1986, with 4.3 inches.

First was 2013, at 5.62 inches.

Some records are meant not to be broken.

-- Brad Schmidt

bschmidt@oregonian.com

503-294-7628

@_brad_schmidt