There's still three weeks left of autumn. Tell that to Mother Nature.

Brace yourself, the season's first snowfall — not just a passing flurry or two — is on the way. The National Weather Service in Pittsburgh has issued a winter weather advisory for Butler County and parts of Western Pennsylvania from 1 a.m. Tuesday to 7 p.m. Wednesday.

A winter-although-it's-still-fall storm is expected to dump two to four inches on the county.

“Travel could be very difficult,” the advisory said. “The hazardous conditions could impact the morning or evening commute.”

The predicted snowfall, however, is not as bad as when the advisory was first posted Sunday night. The initial forecast was for four to six inches.

For today, expect rain, according to the weather service. The rain will transition into snow showers likely about 8 p.m., with low temperatures around 30 degrees.

Snow accumulation of less than one inch is possible tonight. On Tuesday, the snow really hits, with the high near 32 and west winds of 10 to 14 mph, and gusts as high as 28 mph.

The weather service said there will be snow showers overnight Tuesday night, mainly before 1 a.m. Wednesday with a low around 27. The temperature later in the day is to hit 36, with no more snow.