AccuWeather.com

By Alex Sosnowski, Expert Senior Meteorologist

Jul 29, 2010; 11:50 AM ET

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While the economy is playing a role in increased heat-related deaths this summer, high AccuWeather RealFeel® temperatures are a major factor.

The combination of extreme heat, high humidity, very warm nights are taking their toll, increasing heat-related fatalities this year.

The bulk of the deaths are occurring in the elderly, children, homeless and immigrants in the Southwest.

In many states, the number of deaths attributed to the heat are ahead of last year's levels and the average over the years.

Temperatures from the Desert Southwest to the Great Plains, Midwest and the Atlantic Seaboard have been much higher than usual this year during the period from June 1 to the last week of July.

According to Fox News and the AP, 134 illegal immigrants have died in heat-related deaths as of July 15, 2010. This figure is up from 93 in 2009 and 102 in 2008 during the same point in the year.

According to Jan Null, Adjunct Professor of Meteorology at San Francisco State University, as of midsummer 2010, there have been 25 hyperthermia deaths of children left in cars. The average for the entire year, during the period from 1998 through 2009, was 37.

While we cannot say for sure if the increase in the number of heat-related deaths is up solely because of hotter-than-average weather conditions, it is likely a major contributor in addition to other related weather conditions.

Stressed parents scrambling to get to work and forgetting their toddler is still in the car, seniors cutting back on cooling their home and medication so they can pay other bills, and more homeless people due to economic conditions could be contributing factors to the greater death toll so far this year.

However, the higher the temperature, especially the RealFeel temperature, the more stress on the body. Hence, the greater risk of heat-related illness or death.

A Millennium Park security guard uses a towel to wipe her face as temperatures climbed into the 90s Monday, July 17, 2006, in Chicago. In 1995, approximately 700 people died in Chicago during a heat wave spanning five days. RealFeel temperatures soared past 115 degrees. (AP Photo/Julio Cortez)

The RealFeel temperature not only incorporates temperature and humidity levels, like the Heat Index, but also factors in wind, UV index, cloud cover, visibility and other parameters.

While records of the humidity, RealFeel temperature and Heat Index are not maintained, accurate temperature records have been kept in many areas for 100 years or more.

So far, this summer is ranking amongst the top-ten hottest on record and, in some cases, at least in parts of the Midwest and the East, it is rivaling the hottest ever.

New York City is on track for its hottest month on record this July. Records date back to the mid-1800s in the Big Apple.

In many cases, it is not only the high temperatures playing a role, but the failure of temperatures to drop off significantly at night, due to higher-than-usual humidity levels.

According to the National Weather Service, average nighttime lows in Tucson, Ariz., from July 1 through 15, 2010, have been the highest since records have been kept. The temperature has averaged 81.8 degrees through July 1 through 28 this year. The hottest month ever was 81.4 degrees during July 1999. A typical July averages 76.5 degrees.

It has been a similar story for much of the Midwest, South and the East this summer. In the major East Coast cities, where many urban dwellings are made of brick, those structures, roads and sidewalks absorb the heat during the day and give it off at night.

High humidity levels inhibit the overnight cooling process not only in those areas, but also over the countryside.

The hot, humid weather is a concern for all ages and interests ranging from those engaging in rigorous sports to spectators. Coaches and camp directors are urged to exercise caution in the hot, humid weather.

It appears temperatures will be a little less extreme on average in central and eastern areas of the nation during August. However, much of the same area that has been hotter and more humid than usual so far this summer will continue to experience at least above-average temperatures.

Computer model's forecast of temperature departures during the middle of August 2010.

If you have had enough of the heat, Long Range Weather Expert Joe Bastardi will be releasing his winter forecast next week on AccuWeather.com. Joe offers in-depth discussions on long-range and tropical weather in his blog.

Joe is concerned that heat may re-emerge in northern areas, after scaling back for a period in August, while a tropical influence evens out temperatures a bit in the Southeast.

Related to the Story:

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This ABC News Health story has more information on how the body reacts to heat and humidity.