Summer isn't over across the Rockies and Mountain West as big thunderstorms increase the chance of floods today. The East and Plains remain quiet, but hot weather returns today. This, and our tropical update, are available at 5 a.m. ET in our daily briefing.

Strong thunderstorms producing damaging winds and increasing the risk of flash flooding will develop this afternoon and evening throughout the Rockies and parts of the Mountain West and Southwest. The WeatherRadar shows several waves of downpours, which could produce flooding in valleys and poor drainage areas.

Additional afternoon thunderstorms will be possible throughout the Upper Midwest and northern Plains, but these won't be nearly as extensive as the ones across the Rockies.

The eastern half of the U.S., from the central Plains to the Atlantic Seaboard, along with the immediate Pacific Coast, will have a sun-filled Friday. The exception will be Florida, where a few afternoon thunderstorms will be possible.

The autumn preview from earlier this week is over, with summer temperatures returning to the U.S. Afternoon highs will at least hit the upper 70s everywhere, with 80s and 90s found throughout the Mississippi Valley, Texas, and the Southwest. The TemperatureRadar has the latest view of today's high temperatures.

The tropics are quiet this week. A tropical wave is forecast to emerge off west Africa over the next couple of days, with development possible by early next week.

Although it has been quiet recently, the Atlantic Hurricane Season peaks in September, and you will want to be ready. Learn more about how our hurricane alerts work here.