Winters in Janesville are cold, with temperatures often dropping below freezing and averaging around -5°C in January. Temperatures gradually warm up in late winter and early spring, reaching averages of 4°C in March and 9°C in April. As summer approaches, temperatures rise steadily, peaking at an average high of 22°C from June to August. Autumn brings a return to cooler temperatures, with September averaging around 17°C before dropping back down into the cold winter months. Overall, temperature fluctuations are moderate, but the coldest months can be quite chilly.