Polar Vortex Collapse: Unsettled April Ahead

The stratospheric polar vortex, responsible for trapping Arctic cold, is undergoing its seasonal collapse. While this indicates a transition away from deep winter, fragmented remnants of the lower-level vortex over North America could still influence weather patterns, potentially pushing cold air southward and causing late-season snow or chills in the northern and eastern United States. This transition occurs annually as the Arctic warms, weakening the temperature gradient that sustains the vortex.

Looking ahead to April, the weather is expected to be varied. The first half of the month, from April 8-12, will see active weather across the central and northern Plains, Mississippi and Ohio Valleys, and the Great Lakes, with scattered showers and thunderstorms, and a risk of localized flooding in the Southern Plains and Lower Mississippi Valley. Cooler temperatures will persist in the Midwest and Northeast due to the lingering effects of the polar vortex.

From April 13-19, a high-pressure ridge in the eastern U.S. could enhance rainfall risks from northeastern Texas through the Mississippi Valley and up to the Great Lakes, particularly around April 13-14, with flooding concerns remaining in parts of Texas and Oklahoma. Temperatures are expected to gradually warm across much of the central and eastern U.S. The latter half of April (April 18-May 1) suggests slightly above-normal temperatures in the western U.S. and the Southeast, with above-normal precipitation expected in the Southwest. Spring 2026 is forecast to bring contrasting conditions, with slower warming in the north and east and earlier warmth in the Southwest, increasing drought and fire risk there.