A heat advisory is in effect in 37 Oklahoma counties until Saturday night, according to the National Weather Service.
An upper-level high pressure is likely to continue over the southern Plains region this week, causing hot afternoons and warm nights. Highs across the state should be near or just above 100 degrees, the service said.
Under the heat advisory: Alfalfa, Atoka, Blaine, Bryan, Caddo, Canadian, Carter, Cleveland, Coal, Comanche, Cotton, Garfield, Garvin, Grady, Grant, Hughes, Jefferson, Johnston, Kay, Kingfisher, Lincoln, Logan, Love, Major, Marshall, McClain, Murray, Noble, Oklahoma, Payne, Pontotoc, Pottawatomie, Seminole, Stephens, Tillman, Woods, and Woodward counties.
A cold front could approach northern Oklahoma late this weekend, but will bring a low chance of rain, forecasters said.
Highs on Monday were 100 in Oklahoma City, 101 in Guthrie, 102 in Lawton and 103 in Frederick.
Tonight's lows will be from the lower 70s to upper 70s.
Skies on Wednesday will remain clear with highs likely from the lower 80s to lower 100s and lows in the 60s and 70s.
• Tonight: Lows from the lower 70s to upper 70s.
• Wednesday: Highs from the lower 80s to lower 100s. Slight chance of rain and thunderstorms.
Oklahoma City-area forecast
• Tonight: Clear. Lows in the lower 70s. Southeasterly winds about 10 mph.
• Wednesday: Mostly sunny. Highs about 100. Southerly winds about 10 mph.
• Wednesday night: Clear. Lows in the mid-70s. Southeasterly winds about 10 mph.
National Weather Service extreme heat safety tips
FEMA extreme heat safety tips
American Red Cross extreme heat safety tips
NWS summer weather safety and survival