By Rosemary Ford and Caitlin Agnew

This article has been edited for length and clarity.

The experiences of the week of June 23-29 have shown that heat waves are more than an inconvenience. They can cause many other problems, from exacerbating the health issues of those caught in their wake to causing electricity demand to soar, taxing an already burdened system. For many, the question becomes: Is this the new normal for summer in New Hampshire? If so, what can be done about it?

On this episode of “The State We’re in,” Melanie Plenda talks with Mary Stampone, the New Hampshire’s state climatologist and an associate professor of geography at the University of New Hampshire whose courses focus on weather, climate and natural hazards, and Matt Kakley, spokesperson for ISO New England, which operates the regional power grid and administers the wholesale electricity in the region.

Melanie Plenda:

Mary, tell us more about the future of our summers. Should New Hampshire expect warmer weather or earlier heat waves? What is going on with our climate?

Mary Stampone:

As average global temperature increases over time, this shift toward a warmer climate will bring with it more extreme heat. Heat waves have already doubled across the U.S., and models indicate that the Northeast region will likely see the greatest increases in heat exposure over the coming decades.

We're already seeing this trend play out in New Hampshire, where the number of days above 90 degrees Fahrenheit have already increased since the mid-20th century, and climate models project nearly twice as many 90+ degrees Fahrenheit days per year by the middle of this century compared to today.

Melanie Plenda:

What led to the June heat wave, and what impact did it have on the region?

Mary Stampone:

This heat wave formed within a weather system known as a heat dome, and in a heat dome, high pressure pushes warm air toward the surface, which suppresses cloud formation and kind of traps that heat and humidity near the surface for several days at a time. Then, as humidity increases, the air temperature feels even warmer and it makes it more difficult to cool off at night. So in addition to the dozens of daily high-temperature records that we set statewide, we also experienced 100+ degree Fahrenheit heat indices, and extreme nighttime temperatures in the 60s to even over 70s Fahrenheit. 

It can affect ecosystems and our water quality. When it comes to humans, we have a region that doesn't have a lot of air conditioning, so the ability for us to cool off is impacted. We're gonna see an increase in the amount of energy needed for indoor cooling over time. This is going to impact our economy in terms of how many hours people can work outside during the day as well as the health impacts for those people whose indoor spaces just don't cool off at night.

Melanie Plenda:

Matt, how is the power grid affected?

Matt Kakley:

Across New England, and really everywhere, weather is the single biggest driver of electricity use. In the summer, that means air conditioning. The hotter it is, the more humid it is, the more people are turning to air conditioning, and the longer and more hours that they're running those air conditioners drives up electricity demand across the regional system, and that means that ISO New England needs to call upon more resources to provide that electricity. That is what we're seeing right now and is largely what we have projected coming into the season. 

More broadly the last several years, we've seen a relatively flat demand due to largely energy efficiency and behind-the-meter solar that has been installed across the region. But as we look out towards the future, and we continue to electrify our heating and transportation systems, we are expecting demand to go up. We are expecting, particularly during periods of hot weather, demand to go up across the system.

Melanie Plenda:

What happens after a heat wave ends? This time we had thunderstorms and even a tornado warning. Is that typical?

Mary Stampone:

Often, persistent high pressure and heat like what we had will move out of the region ahead of cooler air that advances in behind a cold front. So in this pattern, that approaching frontal boundary will lift the very warm humid, unstable air ahead, forming a line of heavy rain and thunderstorms. Usually, under the extreme weather conditions that we had before. These thunderstorms can become severe, producing heavy downpours, strong wind gusts, possibly tornadoes — although tornadoes are still fairly rare here in New Hampshire.

Melanie Plenda:

How is this extreme weather affecting the power grid by summer electricity demands? What do preparations or precautions to keep it up and running look like during the summer as well as the rest of the year?

Matt Kakley:

It’s kind of a matter of short-term and long-term. On a day-to-day basis, we're evaluating what the next day's forecast is going to be. That allows us to schedule the necessary generation for that next day. What we've seen is that more and more, weather is playing a vital role in determining how reliable that system is going to be. It's always been true that weather is the biggest driver of electricity demand, but now as we get more and more weather-dependent resources — solar power, wind power — it's also affecting the generation side. At ISO New England, we've spent a great deal of time trying to get more and better weather data and weather forecasts so that we can add them to our software as we determine what we think is going to be the power demand for the next couple of days. We've added an on-site meteorologist to help us with that to determine exactly how the weather is going to impact the power system. 

We're also looking out towards a future where maybe historical weather is not as relevant in projecting future demand, so we’re working to incorporate more climate modeling into our forecasting to figure out what are the next five, 10, 50 years going to look like and what we need to do as a rule region to prepare for that.

Melanie Plenda:

Let's talk more about the future. What does the future look like for the power grid considering the changing climate?

Matt Kakley:

In the short term, we believe the power system is going to be reliable, but there's a lot of uncertainty as you get further out. That is for a number of reasons.

One is the general uncertainty of what the climate is going to be like in the mid-21st century. So we've worked with the Electric Power Research Institute, known as EPRI, to work on long-term forecasting, both in terms of what we would expect electricity demand from consumers to be but also what we would expect that weather to do to a power system that has more solar or wind power on it. 

That's really what we're trying to do — project out further in the future than we ever really had to. Typically, electric power planning was done over the course of the next decade. Now we're really looking out into the middle of the century to see how would we expect the power system that has a lot of wind power, that has a lot of solar power on it to behave, and what would we expect consumers to need from that powers system, as they look to charge electric vehicles, as they look to heat and cool with heat pumps and things like that. 

What we're seeing is a lot of uncertainty and a lot of variables going on. We've looked to develop better and more sophisticated tools to grapple with all those different variables and see how they play out with each other. What we're ultimately going to see is a power system that is even more sensitive to weather, both at the extremes but then also just on a day-to-day basis.

Melanie Plenda:

What can we expect for the rest of the summer?

Mary Stampone:

Above-normal temperatures, along with potentially increased humidity are strongly favored for the rest of July across all of New England. Above-average temperatures are expected to persist region-wide well into September, so this will likely be an overall warmer-than-average summer.

Melanie Plenda:

Mary Stampone, the New Hampshire state climatologist and an associate professor of geography at the University of New Hampshire, and Matt Kakley, spokesperson for ISO New England — thank you both so much for joining us.

“The State We’re In” is a weekly digital public affairs show produced by NH PBS and The Marlin Fitzwater Center for Communications. It is shared with partners in the Granite State News Collaborative, of which both organizations are members. These articles are being shared by partners in the Granite State News Collaborative as part of our Race and Equity Initiative. For more information, visit collaborativenh.org.