SUMMER'S HERE-HOT DIGGETY!

US in ‘dome’ scorch

Sizzling temperatures fueled by a massive “heat dome” across the US are making for a steamy start to the summer and leaving some 70% of Americans facing temps of 90 degrees or more.

Heat alerts were active through Tuesday night in eight states, from Wisconsin to Kansas — with realfeel temperatures in Indiana expected to hit a sweltering 112 degrees Wednesday, Fox Weather meteorologist Stephen McCloud told The Post.

Oppressive weather covered much of the US Tuesday, from the Southeast up to the Great Lakes region, including in Chicago, where temperatures hit 99 degrees — just shy of the record 101 set in 1988, McCloud said.

The extreme conditions are expected to move South Wednesday to metro areas like Atlanta and Columbia, SC, as well as parts of Tennessee and into Florida, Georgia and Alabama, where a high of 105 is predicted in Macon on Wednesday, forecasters said.

Detroit hit a record 96 degrees Tuesday, as cities like Nashville, Tenn., and St. Louis came close to breaking their own records with blazing temperatures in the high 90s, forecasters said.

‘Stuck in a bubble’

“The South Central and South are really going to bake right on through to the start of the weekend,” Fox Weather meteorologist Geoff Bansen said, adding that residents from Texas to Florida and Georgia will feel the brunt of the oppressive heat now lingering in the Upper Midwest, Michigan and parts of the Ohio Valley.

New York and New Jersey, meanwhile, will be spared from the stifling heat, with showers and thunderstorms expected to start later Tuesday and persist into Thursday.

Conditions will clear up by Friday, with temps in the low to mid 80s over the weekend.

The high temps were being driven by a so-called “heat dome,” which experts likened to a “lid” on a boiling pot.

Heat domes occur when the atmosphere traps hot air that becomes “stuck in a bubble” and acts like a lid or a cap because there’s no mechanism to force it elsewhere, Fox Weather meteorologist Marissa Lautenbacher explained to The Post.

The high-pressure dome suppresses the air, which also continues to warm as it sinks, Lautenbacher said.

“It works kind of like a convection oven,” she said.

Heat domes typically occur a few times per year, Lautenbacher said.

They’re usually triggered by a strong change in ocean temperatures.