Overview
- Extreme heat continues across large swaths of the country with Heat Advisories and Extreme Heat Warnings in effect and heat-index values commonly above 100°F.
- High humidity from monsoonal and tropical moisture is driving dangerous heat-index readings that increase the risk of heat illness for outdoor workers, students and vulnerable populations.
- Wildfires and elevated fire danger in the Pacific Northwest are producing smoke that is degrading air quality across the West and reaching the Midwest and Great Lakes.
- Monsoonal flow is raising the threat of heavy mountain thunderstorms, frequent lightning and localized flash flooding on burn scars and downstream areas, and the NWS has issued mountain storm warnings.
- Forecast models show a likely midweek trough that should bring gradual relief, and forecasters are monitoring an uncertain tropical-wave signal in the Atlantic for possible development later in the week.