As predicted, the hot weather has hit the region in force Wednesday, with temperatures in the 90s and demand for energy rising, prompting Norwich Public Utilities to issue power alerts for Wednesday, Thursday and Friday, and several towns to open cooling centers.

Preston announced Wednesday that the town’s senior center, 42 Long Society Road, and the Preston Public Library, 389 Route 2, will be open as cooling centers from noon to 4 p.m. Wednesday through Friday.

New London and Ledyard earlier this week also announced that their public libraries will be available as cooling centers throughout the week, and that Ledyard’s Bill Library, 718 Col. Ledyard Highway, also will open Saturday.

As excessive heat and humidity continue in large sections of the country and across Connecticut, NPU has issued a power alert and is encouraging customers to voluntarily conserve energy for the next three days.

“While this summer has been relatively mild, given the recent weather, we have to ask our customers to help us get through the first heat wave of 2022,” NPU General Manager Chris LaRose said in a news release Wednesday. “By using energy wisely, customers can save money on their bill and reduce the likelihood of power outages over the next three days.”

NPU expects to see very high demand for electricity through the end of the week and is urging customers to use electricity wisely in the days ahead for two important reasons.

First, a portion of NPU’s annual costs for electricity is based on “peak demand” days, which are based on forecasts from the nonprofit regional transmission agency ISO-New England, that could take place on Wednesday, Thursday or Friday this week. By using energy efficiently for the next few days, customers can help keep overall electric costs, for NPU and themselves, lower throughout the year.

Second, conserving energy will lower the overall impact on NPU’s infrastructure — transmission lines, distribution lines and transformers — allowing the equipment to cool down faster in the early evening hours and overnight, which will help improve overall reliability.

“We’re also asking the public to look out for those who may have a tough time in extreme weather, particularly the elderly or infirm, to make sure everyone stays safe during the extreme heat this week,” LaRose said.

NPU is requesting that customers consider taking simple steps this week to conserve electricity that will have little or no impact on their comfort. These tips include:

• Only run a window air conditioner when someone is home. NPU recommends setting a central AC system to 73 degrees or higher.

• Wait until after 7 p.m. to use major appliances, such as dishwashers or clothes dryers.

• Minimize the use of appliances or devices that generate heat before 7 p.m., including computers, curling irons, hairdryers, and TVs. All can add to the heat in your home.

• Avoid using the oven to cook and consider using a stove, microwave or outside grill.

• Install energy-efficient lighting that runs much cooler than traditional lighting. Only about 10% to 15% of the electricity that incandescent lights use results in light, the rest turns to heat.

• Keep the sun out and minimize heat coming in by installing window coverings.

The National Weather Service on Wednesday evening issued a bulletin continuing the heat advisory through Sunday for the entire area. The heat index — what the combined heat and humidity feels like — for Norwich on Thursday is expected to be 99 degrees, and for the New London area shoreline, 96 degrees.

With overnight temperatures expected to be in the 70s, there will not be much overnight cooling, according to the forecast.

There is a slight to marginal chance of thunderstorms in the area from about noon to 6 p.m. Thursday.

The Connecticut Red Cross issued heat safety tips on Wednesday, advising people to be aware of both temperatures and heat indexes. The agency also cautioned that urban areas may be hotter than outlying areas and asked residents to check on neighbors who might be vulnerable to heat.

The Red Cross also suggested eating smaller, more frequent meals, drinking plenty of water, wearing light-colored, loose-fitting clothing and postponing strenuous outdoor activities, including games. Take frequent breaks when working outside.

The Red Cross has free mobile device apps that offer more than 35 customizable severe weather and emergency alerts. The Red Cross First Aid app offers access to information on handling the most common first aid scenarios, including heat emergencies. Download the apps by searching for “American Red Cross” in an app store or at www.redcross.org/apps.

c.bessette@theday.com