What is a heat wave? The Weather Service defines it as a period of abnormally hot weather that lasts more than two days. Not only does extreme heat create hazards for humans, but it also stresses transportation, utilities, clean water and agriculture. When heat waves occur over a period of weeks to months and are accompanied by drought, the costs can be steep. While the ultimate human and financial toll of the 2021 heat wave won't be known for some time, we do know the toll taken by major heat waves and droughts over the past four decades. Here is a list of the costliest heat waves in the U.S. since 1980 based on data from the National Oceanic and Atmospheric Administration. All dollar figures have been adjusted for inflation.

1. Summer 1988

Estimated cost: $45.4 billion

From June through August 1988, heat and drought across a large portion of the U.S. caused severe losses to agriculture and related industries. Eleven states declared disasters, and water levels in the three largest rivers within the continental U.S. were 45 percent below normal in June. An estimated 5,000 people perished from direct and indirect effects of the heat.

2. 2012

Estimated cost: $34.8 billion

The 2012 drought is considered the worst that has affected the U.S. since the 1930s. Extreme conditions affected more than half the country for most of the year, resulting in widespread loss of corn, sorghum and soybeans, among other crops. The associated summer heat wave was directly tied to 123 deaths, but the estimated number of deaths due to heat stress is still unknown.

3. Summer-Fall 1980

Estimated cost: $33.9 billion

The heat wave that hit the central and eastern U.S. damaged agriculture and related industries. Combined direct and indirect deaths due to heat stress were estimated at 10,000, the highest total by far on this list.

4. Spring-Summer 2011

Estimated cost: $14.2 billion

Drought and heat wave conditions pummeled Texas, Oklahoma, New Mexico, Arizona, southern Kansas and western Louisiana from March through August 2011. In Texas and Oklahoma, a majority of range and pastureland was declared to be in very poor condition for the growing season. Ninety-five deaths were directly tied to the drought and heat wave.

5. Spring-Fall 2013

Estimated cost: $11.9 billion

While an improvement over the historic 2012 drought with improving conditions in most of the Midwest and Plains states, moderate to extreme drought did remain or expand into western states from March through November, causing more crop losses. There were 53 deaths related to the extreme heat.

6. Spring-Fall 2000

Estimated cost: $7.8 billion

A heat wave hit western, central and southeastern portions of the U.S. from March through November. In all, 19 states stretching from Florida to Oregon were affected, with 140 direct deaths.

7. Spring-Fall 2003

Estimated cost: $7.3 billion

A 2003 drought across western and central portions of the U.S. caused major losses to agriculture. The drought and heat wave, which spread across 17 states, directly resulted in 35 deaths.

8. Summer 1998

Estimated cost: $5.8 billion

Severe drought and heat expanded from Texas and Oklahoma eastward to the Carolinas. There were 200 deaths directly associated with the summer's extreme heat.

9. Summer-Fall 2007

Estimated cost: $4.6 billion

Severe drought with periods of extreme heat hit portions of the southeast and the Great Plains, Ohio Valley and Great Lakes area, resulting in 15 deaths and major reductions in crop yields. Streams and lakes also experienced very low water levels.

10. Summer-Fall 2020

Estimated cost: $4.5 billion

The temperature hit an astounding 130 degrees Fahrenheit in Death Valley as widespread drought and record heat affected more than a dozen western and central states for much of the summer and continued into the fall. Crops and livestock suffered, and 45 died. Source - https://www.aarp.org