Winters in Summerville are mild, with temperatures ranging from around freezing to the mid-20s Celsius, averaging around 10 degrees. As spring arrives, temperatures gradually warm up, reaching averages of 15 degrees by March and 18 degrees by April. Summer brings warmer days, with highs often reaching into the low 30s and averages in the mid-to-high 20s. Autumn sees a slight cooling trend, with temperatures returning to around 10-12 degrees by November and December. Overall, Summerville's temperature fluctuations are relatively moderate throughout the year.