We are back to below freezing days and nights till Friday afternoon. Maybe some flurries on Thursday afternoon otherwise dry until Saturday. It will warm to close to normal by Saturday and we should see some rain that afternoon. But big changes start on Sunday with the arrival of a strong arctic front on Sunday. With the passage of the front, we may see snow arriving by Sunday evening. Whether it's flurries or a plowable event will be determined in a few more days. Either way the coldest air of the season will arrive by Monday night and last through much of next week.
Of historical note on this date back in 1912 the coldest reading in Chester County PA history was recorded at Coatesville 1SW and matched on January 22, 1961 at Phoenixville of 19 degrees below zero.