Wauwatosa experiences a cold winter with temperatures often below freezing, averaging around -4°C in January and dropping as low as -27°C in February. As spring approaches, temperatures gradually warm up, reaching averages of 8°C by April and 13°C by May. Summer months bring moderate warmth, with June and July averaging around 21°C, while August remains slightly warmer. Autumn sees a return to cooler temperatures, with September averaging 18°C before dropping to around 3°C in November. Winters are typically the coldest period, with December temperatures averaging near freezing.