LYNN – Temperatures are expected to hit the mid-90s today and stay around 90 on Wednesday, before a cold front brings cooler and significantly dryer weather to the North Shore, according to Frank Nocera, meteorologist for the National Weather Service.Nocera said today?s high temperatures, combined with stifling humidity that has gripped the region for the past several days, will drive the heat index – what it actually feels like to be outside – to 100 degrees.All people, but particularly seniors and young children, should avoid being out in the sun between 10 a.m., and 4 p.m. today during the “peak heating hours,” Nocera said Monday.Nocera said the average temperature for this time of year is 82.But there?s already been four days hotter than 90 degrees in July, Nocera said, and temperatures will be soaring today to the mid-90s and probably reaching 90 again on Wednesday.?The key is to try to limit exercise and physical activity during the peak heating hours, and try to stay hydrated,” Nocera said.Stacey Minchello, director of the Lynn Council on Aging, said the Lynn Senior Center on Silsbee Street will stay open late today until 6 p.m., to serve as a cooling center for seniors seeking shelter from the near 100-degree temperatures.?It just provides air conditioning for anyone who needs it,” Minchello said Monday.The center typically closes at 4, she said.In addition, Senior Center employees will be making wellness checks for the group of about 75 home-bound seniors to make sure they are handling the heat okay, Minchello said.Senior Center employees will visit in person anybody they can?t reach by phone to make sure they?re okay, she said.Minchello also urged seniors to try to do any errands or work outside today either early in the morning or in the evening and to “try to stay out of the direct sunlight.”In Swampscott, the Senior Center there is expected to stay open until 9 p.m., according to Marilyn Hurwitz, director of Swampscott?s Council on Aging.She expects the town?s emergency management team to send out a message today telling residents the senior center on Essex Street will be open to 9 because of the soaring temperatures and high humidity.?If need be I?ll leave somebody here until 9 p.m.,” Hurwitz said Monday.Jean Graham, the marketing and media relations manager for the North Shore Medical Center, said typically these kinds of high temperatures combined with high humidity only leads to “a handful of extra emergency room visits.”?We don?t typically see a huge increase in visits,” she said Monday.And Nocera said relief will finally come late Wednesday afternoon or early Wednesday evening when a cold front moves through the area.Temperatures are expected to reach into the 80s during the day, but the humidity will drop dramatically, he said, as will the temperatures at night.?Thursday night temperatures are going to be in the upper 50s,” Nocera said.The cold front moving through could cause thunderstorms, he said, which could include “strong winds and heavy downpours.”Jeff McMenemy can be reached at [email protected] to Handle Heat and Humidity ? Prepare. Discuss heat safety precautions with members of your household. Have a plan for what to do if the power goes out.? Dress for the heat. Wear loose-fitting, lightweight, light-colored clothing. Avoid dark colors because they absorb the sun?s rays. It is also a good idea to wear hats or to use an umbrella.? Stay hydrated. Carry water or juice with you and drink continuously even if you do not feel thirsty. Avoid drinks with alcohol or caffeine, which dehydrate the body.? Eat small meals and eat more often. Avoid high-protein foods, which increase metabolic heat.? Slow down and avoid strenuous activity. If you must do strenuous activity, do it during the coolest part of the day, which is usually in the morning between 4 and 7 a.m. Take frequent breaks.? Stay indoors when possible. If air-conditioning is not available, stay on the lowest floor out of the sunshine.