Based on typical July weather in Madison, WI, you can expect warm and humid conditions, as July is historically the hottest month of the year with average highs around 82°F (28°C). Average High: ~82°F (28°C) Average Low: ~63°F (17°C) Conditions: Expect very warm and humid conditions, with heat indices occasionally rising into the upper 80s or lower 90s. Rain: While July can be warm, there is a possibility of scattered, afternoon showers or thunderstorms.