Parts of the U.S. have already experienced 100 degree heat. Experts say this summer is going to get even hotter

It’s already hot across parts of the U.S., with some communities seeing 90- and 100-degree days already - and forecasters say it's only going to get worse.

Florida residents have already been laboring under an oppressive heat wave over the course of the last few days, with highs in the 90s. These temperatures are slated to continue through much of the week, with brutal “feels-like” temperatures in the triple digits.

"It’s been a warmer-than-normal spring overall with eight 90-degree-plus days to date. Thursday’s high reaches 93 degrees, matching the temperature we hit back on April 27. In April alone, Jacksonville logged five days of 90 degrees or higher — marking the most 90-degree days in April since 2011, which had nine," News 4 JAX meteorologist Mark Collins explained.

But, now forecasters are warning that other parts of the nation can expect hot temps over the next few months.

“Warmer-than-normal temps are favored over the [United States} for June with the greatest probabilities stretching from the DesertSouthwest through the High Plains,” the National Oceanic and Atmospheric Administration said about June temperatures.

“The dry soil conditions in place along with a strong trend in temperatures (towards warmer values) combined with the North American Multi-Model Ensemble data that supports this warmth have led forecasters to have an increased confidence in the temperature forecast for [the summer months],” the agency added.

Where will it be the worst?

It’s the hottest across the West, with drought expected to persist there and over much of the Plains region. The combination of heat and drought there is a concern for wildfire activity.

The Rockies are also slated to see a “dry trend” next month, while the East Coast and Southwest are likely to experience above-average precipitation.

Humidity has also been a concern, with dew points in the low-to-mid-70s. High humidity can cause more blood flow to the skin and the heart to beat faster, according to the Mayo Clinic. Overexposure to humidity can also lead to overheating, reducing the body’s ability to cool itself through sweat evaporation.

Expected summer heat in the East is projected to be worst in the Northeast and Florida.

Summer-like heat is happening now

The summer-like temperatures are already hitting some areas.

“Last week saw summer-like heat in Austin, Texas. While 90-degree weather is not uncommon there in May, long stretches usually [hold] off till June, Cameron Self, a meteorologist with the National Weather Service’s office in the Houston and Galveston area, told The Associated Press.

“Definitely more like August this week than May,” he added.

Orlando Bermúdez, a forecaster in the Weather Service’s Austin and San Antonio office, agreed, according to The New York Times.

“This is something we see in mid-June and definitely in July and August,” he said. “But this early in May? This is rare.”

In Los Angeles, summer-like temperatures are set to hit the area by midweek. Forecasters are warning that the high could reach 103 degrees in parts of Southern California by Thursday, according to NBC Los Angeles. That could lead to heat advisories for part of the area.

In Louisiana, many areas will see temperatures in the upper 80s by the end of Monday’s workday, according to KPLC-TV. However, forecasters say that the heat index will make many communities feel like they are in the 100s.

“If you have plans to be outdoors working, or fishing or just to enjoy the weather, make sure to drink plenty of water to help stay hydrated,” forecaster Jacob Durham with KPLC warned.