The National Weather Service recently officially adjusted heat indexes in New England to more accurately portray the risk to residents, who are used to lower average temperatures year round than in other areas of the country.

Heat index, also known as apparent temperature, is a measure that combines temperature and humidity and is used by the NWS to estimate how hot people feel. For example, a day with a temperature of 85 degrees Fahrenheit and 80 percent humidity would have a heat index of 95 degrees Fahrenheit.

So, all other things being equal, a person would feel as if they were out in heat that was 10 degrees higher

The adjustment to New England indices was the result of a study released this year by a research team at Brown University chaired by Dr. Gregory Wellenius, an associate professor of epidemiology.

"There is mounting evidence from around the world that even moderately hot days may put people at risk of death or needing hospitalization, but how hot is too hot varies by location," Wellenius said. "We wanted to understand how moderate heat affects people's health risks, specifically in New England."

The team, Wellenius continued, found that New Englanders are at higher risk of death and hospitalization on very hot days. It also discovered they can face health risks on days with just a moderately high heat index.

"Days with a heat index of 95 degrees Fahrenheit or higher were associated with 7.5 percent more visits to the emergency department and 5 percent more deaths," Wallenius said. "That adds up to a lot of extra deaths and hospital visits."

That conclusion was fleshed out by one of the study's samplings from Rhode Island. There, among its 1 million residents, days with a heat index of 95 degrees or more account for about 300 extra emergency department visits and 13 deaths each summer.

Heatstroke and heat exhaustion were the most commonly reported afflictions.

According to the Mayo Clinic, heatstroke is a condition caused by the body overheating, typically after prolonged exposure to or physical exertion in high temperatures. It can occur if body temperature rises to 104 F (40 C) or higher.

As such, heatstroke requires emergency treatment. Untreated, it can quickly damage the brain, heart, kidneys and muscles. This worsens the longer treatment is delayed, increasing risk of serious complications or death.

Heat exhaustion is a condition whose symptoms may include heavy sweating and a rapid pulse, a result of the body overheating.

Causes of heat exhaustion include exposure to high temperatures, particularly when combined with high humidity, and strenuous physical activity. Without prompt treatment, heat exhaustion can lead to heatstroke, a life-threatening condition.


Over time people tend to adapt to the climate where they live. What this means is that a day with a heat index of 95 degrees Fahrenheit will tend to be more dangerous to a New Englander than to someone who lives in the southeast U.S. and experiences many more such days each year.

Wellenius explained that this is partly due to how our bodies adapt to heat over time and also due to how we adapt the way we live, based on the typical weather.

"We see potentially important differences in how people adapt to heat, even within New England," Wellenius said. "For example, hot days tend to occur more frequently in Rhode Island and parts of New Hampshire, as compared to Maine. Residents of Maine are also less likely to have home air conditioning, potentially putting those in Maine at higher risk on hot days."

Regionally, then, people need protection and prevention, said Robert Tarnas, a family physician at the primary care Pownal, Vt., campus of Southwestern Vermont Medical Center.

"If you are exerting yourself on a hot day, and you get thirsty, your body is already alerting that you've gone too far," Tarnas said. "The elderly, in particular, and people on certain medications that can limit the body's hydration, should be especially careful."

Tarnas recommended:

- Always have plenty of water on hand and make sure to drink before any kind of activity in the heat.

- Keep drinking even when not thirsty.

- On especially hot days, if you have access to air conditioning, take advantage of it and stay in it as long as possible.

- If away from air conditioning, try to find a place in the shade or one exposed to good air flow.

- Err on the side of caution in all you do

- People on the following medication types should be extra careful: Those that narrow blood vessels (vasoconstrictors), regulate blood pressure by blocking adrenaline (beta blockers), rid the body of sodium and water (diuretics), reduce psychiatric symptoms (antidepressants or antipsychotics) and stimulants for attention-deficit/hyperactivity disorder (ADHD)

Wellenius echoed such medical advice, adding that prevention is the key, especially for New Englanders.

"The most important message is that [people] need to protect themselves and their loved ones on days of both moderate and extreme heat," Wellenius said. "Some individuals, such as children, older adults, pregnant women, and those that work outdoors may be at particularly high risk of heat-related illnesses."

For more information on heat indices and heat illness, visit and The full report on the Brown University study can be found at

Reach award-winning freelance journalist Telly Halkias at or on Twitter @TellyHalkias.