Winter Storm Warnings Issued in Montana and Idaho as Heat Dome Expands Across 30 States

Winter storm warnings are in effect for southwest Montana and parts of central Idaho, while a heat dome is expected to cover 30 central and eastern states from July 2-6. The National Weather Service has warned of heavy, wet snow through Monday in northwest Beaverhead County, Montana, with up to 3 inches near mountain passes and more than 6 inches at higher elevations.

The same high-pressure system is projected to push temperatures into the 90s and low 100s across the Midwest, Southeast, and Northeast. Heat index values are expected to exceed 100 degrees Fahrenheit in parts of Ohio, North Carolina, and Washington, D.C. The pattern is forecast to persist through the July 4 weekend, with little overnight relief and elevated risks of heat-related illness.

Meteorologists attribute both extremes to a single jet-stream configuration. A northern ridge supports the heat dome, while a southern dip draws cold air into the northern Rockies. A blocking high-pressure area has slowed the usual movement of weather systems, allowing the contrasting conditions to remain in place simultaneously.