Midwest low pressure draws unusual November warmth into New York and Boston

New York and Boston have experienced unusually warm conditions for early November, with temperatures nearing 23C in recent days. The late spell of summerlike weather has put the two cities about 7-10C above their expected temperatures, even as autumn advances across the northern hemisphere.

The warmth has extended beyond the eastern United States into parts of eastern Canada. Temperatures there have risen above 20C, placing them roughly 10-15C higher than normal for this point in the year. Both areas have felt the effects of exceptionally warm air being drawn northwards from the Gulf of Mexico.

An area of low pressure over the US midwest is responsible for that movement of warm air along its eastern side. The system is forecast to move gradually east, allowing temperatures in the affected areas to return closer to their seasonal averages as it shifts.

Elsewhere in the United States, severe thunderstorms have brought disruptive conditions this week. Numerous flood warnings and evacuation warnings have been issued across several states. Polling stations have also been affected by the weather, including those in Florida, Oklahoma and Colorado.

In Keyes, Oklahoma, a tornado touched down during the week's powerful thunderstorms and forced a polling station to relocate. The tornado caused extensive damage throughout the town, although no casualties have been reported. Across many of the states affected by severe weather, officials have sought federal funding assistance following widespread damage to homes and infrastructure.

Across the Atlantic, thunderstorms and torrential rainfall associated with another low pressure system have prompted severe flood warnings in Mediterranean areas. Authorities in southern France, Corsica and Sardinia issued the warnings this week as the unsettled weather affected the region.

Rainfall totals of 50-100mm are forecast over the coming days. Localised amounts could exceed 100mm in the southern French regions of Provence-Alpes-Côte d’Azur and Occitanie, and on Corsica. In places where the heaviest rain persists longest, between 70mm and 80mm could fall over a single 24-hour period.

The Mediterranean forecast also points to further rainfall next week, with low pressure expected to remain the dominant influence on the region's weather. That continuing pattern contrasts with the eastward movement of the US midwest system, which is expected to ease the unusual warmth in eastern North America.