Hot and humid air returns to southern Wisconsin this Sunday, June 30, as a First Alert Day has been issued due to the risk of strong to severe thunderstorms developing by the afternoon and evening hours.
Heat and humidity dominate southern Wisconsin
Temperatures will climb into the upper 80s to low 90s Fahrenheit (31–33°C), with heat index values potentially peaking between 95 and 100°F (35–38°C) during the late afternoon. A steady southerly breeze and rising dewpoints will contribute to a muggy, oppressive feel, especially in urban areas like Madison and Janesville. Despite the sweltering atmosphere, heat indices are expected to remain just below advisory thresholds.
Storm risk grows through the afternoon and evening
Scattered thunderstorms are expected to develop later in the day, primarily along and ahead of a cold front pushing through southern Wisconsin. While dry air aloft may reduce the overall coverage of rainfall, any storms that do form could be intense, capable of producing gusty winds, particularly across areas north and west of Madison, including parts of Sauk, Columbia, and Dodge Counties.
There is still moderate uncertainty regarding storm coverage and exact timing, with weather models showing some disagreement on how widespread the activity will be. However, the potential for severe weather remains notable, especially during the late afternoon and evening hours.
Looking toward Independence Day
Conditions will ease slightly into early next week, with lower humidity and mostly dry skies expected for Tuesday and Wednesday across southern Wisconsin. However, as a large upper ridge shifts east, storm chances may return by Thursday, including July 4th, bringing another round of showers and thunderstorms to the region. This pattern would mirror the unsettled conditions experienced over the past week.
