MARQUETTE, Mich. (WLUC) -The heat returns early next week. An upper-level ridge in the jet stream will bring unseasonably hot air to the region. Temperatures will trend 15-20 degrees above normal for this time of year. Download the First Alert Weather App here Highs will soar into the 90s for Monday and Tuesday. However, Gulf moisture surges in, increasing humidity. This will cause heat index or feels-like temperatures to reach around 100-105°. It will feel rather steamy and tropical at times.