After a day of record-tying heat, a synoptic-scale weather pattern consisting of a large ridge to the west and a large, high-amplitude negative-tilt trough centered over the Northeast.

The upper-air winds were very strong for this time of year, and this brought in some chilly temperatures to most of Maine. The dewpoints on Friday were close to 73°F (6:50pm 8/25/03 it was 73.8°F). Once this blast of cool, dry air rolled into Maine, the dewpoints dropped rapidly. By Sunday, August 24, 2003, the dewpoint at Weather Maine had dropped to a pretty dry 31.1°F! That is a drop of over 40°F over one weekend. A marked dewpoint drop is a sure sign of the arrival of a new air mass.
The NWS (National Weather Service) issued frost warnings for Northern Maine's weather zones during this weekend, but there was no widespread frost over our Southern Zones. Sanford did get into the 30's on Saturday night, which after the recent hot weather, is quite a shock to the body. Welcome to sniffle season.