Arctic air will sweep across the eastern United States, frost is expected as far south as Florida
The eastern half of the United States and part of southeastern Canada are about to be hit by an outbreak of Arctic air and a marked cold spell. For the first half of November, this will be an exceptionally cold air mass that will bring record-breaking low temperatures, especially across the southeastern U.S.
The cause of this cold outbreak is strong blocking of the atmospheric flow over parts of the Arctic adjacent to northern Canada and Greenland. This pattern significantly distorts the jet stream in that region, leading to a “push” of cold polar air far to the south. Over the western half of North America, a pronounced ridge of high pressure is strengthening from northern Mexico up into western Canada. On its eastern flank, cold air is beginning to flow southward in a broad corridor from the north and northwest. Beneath a deep upper-level trough, a low-pressure system is forming over southeastern Canada, the Great Lakes region, and the northwestern U.S. This low will deepen through Sunday while moving southward. In its wake, precipitation will turn to snow, and a snow cover is expected to develop across a broad swath near the U.S.–Canada border. The heaviest snowfall is expected downwind of the Great Lakes, where the still relatively warm water will produce a pronounced lake-effect event with heavy snow showers and even thundersnow. Local accumulations could reach up to half a meter of snow — quite significant for early to mid-November. Still, from a historical standpoint, the most remarkable part will be the intrusion of cold air far into the southern U.S.
By Sunday, a surface high will strengthen over the central United States, allowing very cold air to surge far south, reaching even Florida. The cold wave will peak on Monday across Alabama, Tennessee, Georgia, and parts of the Carolinas, with temperatures running 10–17 °C below seasonal averages. The drop compared to Sunday will be dramatic — for example, Atlanta’s high will fall from around 17 °C on Sunday to just about 4 °C on Monday. A brisk northwesterly wind with gusts near 50 km/h will make it feel as cold as −5 °C, with even lower wind chills farther north and west.
On Monday, the cold front will sweep across Florida. The strongest cooling will occur in the northern half of the state, with temperature drops of up to 15 °C. Nighttime temperatures will plunge even further — as winds ease and skies clear, Tuesday morning lows could reach −2 °C in northern Florida. This may have agricultural impacts, and could also lead to the odd sight of iguanas falling from trees — as they become lethargic and lose grip when temperatures drop below 7 °C. Tuesday morning will be freezing across much of the eastern half of the U.S. (except southern Florida), with daily minimum records likely broken in many places.
While the southeastern U.S. will be hit by an unusually cold air mass, the western half of North America will experience the opposite extreme, with very warm air flowing northward. Temperatures there will run 10–15 °C above normal, and in some places even higher, potentially breaking warm records. The cold spell in the eastern U.S., however, will not last long — the high-pressure system will weaken and shift eastward, allowing the cold flow to subside by Tuesday. In the following days, temperatures will gradually return to normal. Still, this brief but intense outbreak of Arctic air could cause significant agricultural damage.
