By ANI FREEDMAN, InDepthNH.org

Heat has ravaged New Hampshire this week, with temperatures soaring into the high 90’s in southern New Hampshire beginning on Tuesday and lasting through Thursday. The National Weather Service issued an excessive heat warning for southern New Hampshire, with “heat index values up to 105 expected.”

“What makes it unusual is that it’s occurring in mid- to late-June,” said Dr. Eric Hoffman, professor of meteorology at Plymouth State University. “It is much different and probably more noticeable to people.”

New Hampshire is currently under what meteorologists call a heat dome. Hoffman explained that means the pressures in the upper atmosphere are higher than in the lower atmosphere, which compresses the warmer temperatures to create a dome as hot air expands upward.

Hoffman said New Hampshire’s hardest-hit areas are south and east of the lakes and mountains. Manchester and Nashua have hit highs of 97 degrees Fahrenheit, with heat indices over 100 degrees. But New Hampshire has experienced heat like this in June before, Hoffman said.

“I was looking at record-highs in previous years for all this week,” Hoffman said, “and the record-high in Concord is 98.”

This atypical heat has to do with the jet stream, Hoffman said, which is “a ribbon of fast-moving air about 10km above earth’s surface.” The jet stream’s pattern dips and rises—as it dipped further south near Montana, unseasonable snow fell as the Rockies became cooler than typical for June. Meanwhile over New England, he said, the jet stream moved further north, corresponding to a surge in higher temperatures.

Hoffman said the dome will affect areas as far west as Chicago, and as far south as the mid-Atlantic. Once you start getting down to Washington, D.C., he said, these hot temperatures are much more normal.

Hoffman could not acknowledge that this specific event was caused by climate change, but he did say this type of heat wave is likely to be more frequent as the Earth continues warming. He’s anticipating another heat wave or two this summer as well, especially in New Hampshire’s hottest months of July and August.

“I’d expect more days in the 90s,” Hoffman said.

In the National Weather Service’s excessive heat warning, they advised those impacted to “drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors.”

They also cautioned to “not leave young children and pets in unattended vehicles. Car

interiors will reach lethal temperatures in a matter of minutes.”

Dartmouth Health also put out a press release with precautions to take during the heat wave:

• Hydration is key—don’t wait until you’re thirsty. Sip water throughout the day, even if you don’t feel dehydrated. Avoid sugary drinks and alcohol, which can dehydrate you further.
• Seek cool relief. Limit strenuous activity during the hottest part of the day. If you must be outside, wear loose-fitting, lightweight clothing and sunscreen. Spend time in air-conditioned spaces whenever possible, such as libraries, shopping malls, or cooling centers.
• Listen to your body: Be aware of signs of heatstroke or heat exhaustion, such as dizziness, headache, or excessive sweating. If you experience any of these symptoms, move to a cool place, remove excess clothing, and drink fluids. If symptoms worsen, seek medical attention immediately.

• Never leave children or pets unattended in a parked car, even for a short period. The temperature inside a car can rise rapidly, leading to heatstroke or death.
• Check in on older neighbors or relatives who may be living alone. Heat waves can be particularly dangerous for older adults.
• Schedule air-conditioned activities during the hottest part of the day. Consider visiting a library, senior center, or shopping mall for a cool respite. A list of cooling centers and open public swimming pools around New Hampshire may be found on WMUR-TV’s website.
• If you live alone and have concerns about managing during the heat wave, reach out to a friend, family member, or local social service agency for assistance.