Today, Monday, August 31st was a cloudy and cool day. Central PA was about 10 degrees below average for this time of the year. The high temperatures topped out in the upper 60s and lower 70s. The average high temperatures for today is 78 degrees. So, why was today so cool?
We had a couple of factors that kept the temperature down. The winds coming out of the southeast, a cloudy sky, and showers. When there is an easterly component to the wind Central PA struggles to warm. Cool moist air from the Atlantic Ocean keep the temperature down.
A high-pressure system is just to the northeast of Pennsylvania and a low-pressure system to the south caused the cool day. The winds around high-pressure spins clockwise and the winds around a low-pressure system spin counterclockwise. This allows the winds to come out of the southeast. The cool and moist air from the Atlantic Ocean moves into Central PA. The cooler air settles in the valleys east of I-99. The cool moist air leads to more clouds forming. The more clouds you have the cooler the day will be.