Suisun City's winters are cool, with temperatures often dropping below freezing and averaging around 11°C in January. By spring, the city warms up significantly, with April temperatures averaging 15°C, marking a mild transition into warmer months. Summer is warm to hot, with June through August temperatures consistently above 20°C, although July's average temperature of 19°C hints at slightly cooler days. Autumn brings a return to milder conditions, with October temperatures averaging 16°C, before cooling down again in the winter.