It’s going to be warmer than average this week, but there’s nothing unusual about this latest stretch of warmer weather, a National Weather Service meteorologist said.
“I think we could see 90,” John Darnley, one of the meteorologists based in Moon, said of Tuesday’s high temperature.
The National Weather Service tweeted Monday that the heat index is going to be nearly 90 degrees this week.
We will be getting a taste of summer for the next few days due to upper-level ridging. Make sure to stay hydrated out there! pic.twitter.com/SaODQFARFT
— NWS Pittsburgh (@NWSPittsburgh) September 9, 2019
The index is what the temperature feels like to the human body, according to the NWS.
While it’s significantly higher than the September average of 64 degrees for Pittsburgh, stretches of elevated temperatures aren’t unusual this time of year, Darnley said.
Air currents change with the season, and as the jet stream’s flow changes from the flow that makes summer warm and winter cold, these fluctuations happen, Darnely said.
This week’s warmer temperatures are caused by what meteorologists call “upper level ridging.” It’s when air is blowing downward toward the earth in the high levels of the atmosphere, creating heat, Darnley said.
Because it was drier than usual in August, it’s easier for the temperature to rise. The latest forecast shows highs in the 80s through the rest of the week, he said. It will change by this time next week, when wet, cooler weather will arrive.
The record high for Sept. 9 is 98 degrees, set in 1882. Monday’s high is forecast at 78 degrees, but it could top 80, Darnley said.
The last big September stretch of higher temperatures was a nine-day stretch between Sept. 19 and 27 in 2017 when the highs ranged from 84 to 91 degrees, according to the NWS.
A five-day hot streak from Sept. 18 through 22 in 1895 saw temperatures between 92 and 94 degrees.
The most recent September that was cooler than normal was 1984, when the average high was 61.4 degrees, according to the NWS.
People can expect more warm weather followed by cooler days at the month continues, Darnley said.
“This is pretty common for us to see,” Darnley said. “It’s pretty typical of Pittsburgh weather in September.”
