Why is there a heatwave in the Great Plains and South?

As of July 31, 2024, there is a heatwave in the Great Plains and South (1). The heat wave was caused by a strong upper-level high-pressure system situated over the southern-tier of the United States.

This system is driving temperatures into the low to mid-100s in the Central Plains and southern High Plains, and into the mid- to upper 90s in the Middle and Lower Mississippi Valley, as well as the Southeast and southern Mid-Atlantic regions. The regions affected include parts of states like Kansas, Oklahoma, Texas, and areas stretching eastward toward the Mississippi River.

Which cities or areas are affected by the heatwave?

There are heat advisories, excessive heat warnings, and heat watches across a broad swath of the United States on July 31.

While most of the heat advisories and warnings are impacting the central and southern Great Plains and Deep South, there is also an excessive heat watch in effect throughout the Pacific Northwest. Cities impacted include:

• Boise, Idaho
• Charleston, South Carolina
• Dallas, Texas
• Des Moines, Iowa
• Kansas City, Missouri
• Memphis, Tennessee
• Miami, Florida
• New Orleans, Louisiana
• Omaha, Nebraska
• St. Louis, Missouri
• Portland, Oregon

How long will the heatwave last?

The current heatwave started earlier this week and is expected to persist through at least Thursday, August 1.

An approaching cold front will bring some relief to the Middle Missouri Valley and Central Plains by Thursday. However, a new upper-level ridge is developing over the western United States, which will cause temperatures to rise significantly in those areas, potentially extending the overall period of extreme heat in the country.

Are there any alerts in place?

There are numerous heat-related warnings and advisories issued across the affected regions. These include heat warnings due to expected high temperatures and humidity, leading to heat indices reaching 105-110 degrees, with some areas experiencing up to 115 degrees.

Residents and visitors are advised to stay updated with local emergency management agencies for any potential evacuation orders or the location of evacuation centers, especially in wildfire-prone areas.