Metro-east under heat advisory as heat index values break 100 degrees | Belleville News-Democrat

Forecasters have put several metro-east counties under a heat advisory beginning 1 p.m. Monday as the hot temperatures in the area are accompanied with high humidity levels.

St. Clair, Jefferson, Madison, Monroe, Saint Charles and St. Louis counties are all under the advisory — which states temperatures will reach up to 104 degrees due to temperatures in the high 90s and dewpoints around 70.

“People in the advisory area are advised to avoid poorly ventilated areas and prolonged work in the sun,” the advisory states. “Also, keep plenty of liquids on hand and try to stay in an air conditioned environment.”

The heat index, what hot weather feels like to the body, takes humidity into account in addition to temperature. When the air is more humid, it makes it harder for sweat to evaporate, which means that people’s bodies are less effective at cooling down.

This week’s forecast for the metro-east from the National Weather Service:

Today ... Mostly sunny, with a high near 96 degrees. Heat index values as high as 101 degrees. Southwest wind 6 to 11 mph increasing to 12 to 17 mph in the afternoon. Winds could gust as high as 26 mph.

Tonight ... Partly cloudy, with a low around 74 degrees. Southwest wind 6 to 11 mph.

Tuesday ... Mostly sunny, with a high near 96 degrees. Heat index values as high as 105. Southwest wind 5 to 8 mph.

Tuesday Night ... Partly cloudy, with a low around 74 degrees. South wind around 6 mph.

Wednesday ... Sunny, with a high near 96 degrees. Southwest wind 5 to 8 mph.

Wednesday Night ... Partly cloudy, with a low around 77 degrees.

Thursday ... A 40 percent chance of showers and thunderstorms. Partly sunny, with a high near 92 degrees.

Thursday Night ... A 40 percent chance of showers and thunderstorms, mainly before 1 a.m. Mostly cloudy, with a low around 72 degrees.

Friday ... A 30 percent chance of showers and thunderstorms, mainly before 1 p.m. Partly sunny, with a high near 89 degrees.

Friday Night ... Partly cloudy, with a low around 70 degrees.

Saturday ... Sunny, with a high near 90 degrees.

Saturday Night ... Partly cloudy, with a low around 69 degrees.

Sunday ... A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 89 degrees.