All of Iowa is under a Heat Advisory through Friday night, as afternoon and evening temperatures will be in the upper 90s to 100 degrees and heat index values will be above 100. An Excessive Heat Warning begins at noon in southeast Iowa and will last through Friday evening, due to even higher temperatures to 100 and heat index values as high as 110.

Here's a slideshow of the expected Heat Index Values from Thursday noon through Friday night:

A cold front will cross the state late Friday night and bring a few thunderstorms overnight and drop in temperatures. Highs will return to the upper 80s to 90 degrees Saturday and Sunday.

Keep track of all the weather at www.who13.com/weather.

A Heat Advisory goes into effect at noon on Wednesday and will remain in place through 9 PM on Thursday. The combination of high temperatures and high humidity will lead to heat index values in the afternoons and evenings above 100 in the next few days. This can lead to heat illness.

Temperatures look to stay at 90 or above for the next 7 days.

The longest stretch of 90+ degree weather for Des Moines was in 1936 from June 25 to July 19 that year. That was 25 days of 90+ degree heat.

A more recent 90-degree stretch of days happened in 2012 when we had 16 days from July 11 to July 26. In 2011, we had 13 days of 90+ degree highs from July 15 to July 27.

For 2023, we have only hit 90+ in Des Moines 6 days this year:

• June 15 - 90
• June 22 - 90
• June 23 - 91
• July 4 - 92
• July 11 - 93
• July 24 - 90

If you'll be spending an extended amount of time outside, stay hydrated, wear light and loose-fitting clothes, and find as much shade as possible. Watch for the signs of Heat Exhaustion and Heat Stroke. Heat illness is the top weather-related killer.

You can find a list of cooling shelters in Polk County here.

Keep track of the conditions at www.who13.com/weather.