Extreme Heat Alerts: Danger in 21 States

Heat warnings and alerts have been issued for 110 million people in 21 states over the coming days.

The western part of the country is facing dangerously extreme and potentially historic heat with temperatures that could reach up to 115 degrees.

The National Weather Service office in San Francisco warned that this heat event could last from 6 to 12 days.

This makes it the longest period of extreme temperatures the Bay Area has seen in at least 18 years.

Extreme Heat and Critical Weather Warnings

On Tuesday, several daily heat records were broken, and more than 130 could be broken by next Tuesday.

The weather service warned of an exceptionally dangerous situation.

We are entering a potentially historic and deadly heat event.

Heat is the leading cause of weather-related deaths in the U.S.

We are likely to increase that statistic if preparations are not taken seriously.

Excessive heat warnings are in effect for much of California, southern Nevada, and parts of Arizona, Washington, and Oregon.

An excessive heat warning means potentially deadly conditions with high or very high risk for much of the population.

Prolonged heat offers little or no relief during the night.

Temperatures had already reached 77 degrees in the Bay Area with 18% humidity at 5 a.m. on Wednesday.

In the plains and the southeast, the heat index could reach between 100 and 115 degrees on Wednesday.

Little Rock, Arkansas, could record a heat index of 116 degrees, while Phoenix, Arizona, will reach 113 degrees.

Excessive heat and humidity will stretch from Nashville to New Orleans on Wednesday and Thursday.

Slightly cooler temperatures will arrive on Friday.

Extreme heat brings an increased risk of wildfires.

About 4 million people in California are under Red Flag warnings.

The warnings urge caution with open flames, an additional risk with July 4th fireworks.