An Extreme Heat Warning has been issued for most of New Jersey beginning Wednesday, with forecasters warning that a prolonged and potentially historic heat wave could bring some of the hottest weather the region has experienced in more than a decade.

The National Weather Service upgraded Extreme Heat Watches to Warnings for 18 counties, with the alert taking effect at noon Wednesday. Atlantic, Cape May, and Cumberland counties remain under an Extreme Heat Watch.

Forecasters say daytime high temperatures will range from 95 to 105 degrees through at least Friday, while the combination of heat and humidity will make it feel as hot as 100 to 110 degrees.

“The intensity and length of the extreme heat will exacerbate impacts to both people and infrastructure,” the National Weather Service said. “This is not the kind of heat event we see every year, and could be the hottest period of weather the area has experienced since July 2011.”

Tuesday will serve as a preview, with temperatures climbing into the upper 80s and low 90s. Thunderstorms are possible during the afternoon and evening, mainly along and north of Interstate 78, with damaging winds and frequent lightning posing the greatest threats.

The dangerous heat will build on Wednesday as highs surge into the mid- to upper-90s, with increasing humidity pushing heat index values to between 100 and 105 degrees. Isolated afternoon thunderstorms are also possible.

The hottest conditions are expected Thursday and Friday, when temperatures could top 100 degrees in some locations and heat indices may reach 110 degrees. Meteorologists say daily record highs could be broken on both days.

While temperatures are expected to ease slightly over the weekend, conditions will remain dangerously hot. Highs on Saturday are forecast to remain in the mid-90s to near 100 degrees, with a greater chance of afternoon and evening thunderstorms developing Friday and continuing into the holiday weekend.

By Sunday and Monday, temperatures are expected to settle into the low- to mid-90s.

Officials are urging residents to stay hydrated, limit strenuous outdoor activity during the hottest part of the day, check on elderly neighbors and vulnerable family members, and never leave children or pets inside parked vehicles.