The National Weather Service has expanded its HeatRisk map nationally, in time for Memorial Day weekend.
The map predicts heat risk for the next seven days, with a color-coded map to simplify the warning levels. It’s similar to other predictive maps that forecasters issue, such as for storm risks, and reflects the reality that excessive heat will be a growing weather risk in a warming world. People planning to go to the beach, outdoor concerts, or take a summer hike can now plan accordingly with localized extreme heat data, according to Jessica Lee, public weather services program coordinator for the National Weather Service.
“Heat is the number one weather-related killer in the United States,” Lee said.
Last year, 119,605 people visited the emergency room for a heat-related illness in the U.S. Charlotte averages 45 days of extreme heat, according to an analysis of federal heat wave data by financial risk research group ValuePenguin. This is a major problem for the fifth of the city that might have trouble finding relief from extreme heat due to economic or social factors, such as lack of air conditioning or tree cover.
Lee said that heat risk occurs on a spectrum, and the map’s colors correspond to less or greater threat. Green areas are at “little to no risk.” Yellow and orange areas pose a concern for individuals who are sensitive to heat, such as children, older adults, low-income community members, people suffering chronic health conditions and unhoused individuals.
This group also includes first responders, construction workers, athletes and other people who work outside. In North Carolina,there are no state-level occupational safety and health standards for heat, putting outdoor workers at greater risk for heat-related illness.
“[The map] is especially useful for populations who are heat sensitive or for decision-makers who may need to make decisions below our typical heat advisory, excessive heat warning criteria,” said Lee.
Periodic activity breaks and shelter can help people cool off. Water redistributes heat in the body and helps with sweating, so drink plenty of fluids while avoiding alcoholic and caffeinated drinks. Lee recommends dressing appropriately for the weather by wearing light, loose-fitting clothing that protects from the sun.
“And never, never leave children or pets in vehicles,” said Lee. “That’s just kind of a year-round thing.”
The sun goes down, but temperatures stay up
The most extreme risk is denoted by a different color: threat-level magenta. Anyone without effective cooling and hydration is particularly vulnerable. Parts of south Florida and Texas will experience extreme heat this holiday weekend with “little to no overnight relief.”
“People think, ‘Oh, the sun’s gone down. Everything’s fine!’ [That’s] not necessarily true,” Lee said.
Urban heat islands form when concrete and other built materials absorb heat during the day and then radiate that heat throughout the night, keeping temperatures high. For people without access to shelter or air conditioning, this interrupts the body’s nocturnal recovery time. When the body can no longer cool down, damage to the brain and other organs may ensue, according to the U.S. Center for Disease Control.
The CDC released a similar dashboard using the same data that focuses more on public health information. The application offers similar advisories but offers recommendations for avoiding or reducing heat stress and information regarding air quality by ZIP code. Poor air quality adds additional stress to people who are already vulnerable to heat, such as those with asthma or heart conditions.
The HeatRisk map is currently open for public comment. Users can provide feedback on the National Weather Service website.
Wildfire risk shifts with the temperature
As temperatures rise, the risk of wildfires also increases during North Carolina’s two fire seasons, in the fall and spring. Since 1973, Wilmington, Greenville and the Triad added over a week to their respective fire seasons. When these fires ignite, they can cost millions to extinguish. For example, the 2022 Ferebee Road Fire in Hyde County cost $2.6 million to mobilize personnel and equipment alone, not including damages.
“Higher temperatures and lower relative humidity quickens the drying out of grasses, shrubs, woody debris, and any biomass that can burn in a wildland fire,” said Molly Hunter, science advisor for the U.S. Bureau of Land Management’s Joint Fire Science Program in a written statement.
“Under dryer and warmer conditions, wildland fuels are more available to burn,” Hunter said.
By contrast, the Charlotte, Asheville, and Raleigh areas experience fewer days when conditions are right for wildfires than 50 years ago, despite rising temperatures and decreasing relative humidity. Hunter said local windspeeds may play a role, since “there are no real discernible trends between climate change and windspeed.”
