St. Catharines' winters are long and cold, with temperatures often below freezing, averaging around -2°C in January, but occasionally reaching as low as -17°C. Spring arrives slowly, with March marking a gradual warming trend, but April brings more significant temperature fluctuations, still cool at night, but warm by day. Summer is mild and pleasant, with June to August temperatures rarely straying far from the mid-20s, ideal for outdoor activities. Autumn is similarly temperate, with September seeing the last of the warmth before a cooler November and December bring winter's chill back. Overall, temperature stability increases through summer but drops significantly during the colder months.