Groningen's winters are cold and occasionally frosty, with January averaging just 2 degrees Celsius. As spring approaches in March and April, temperatures rise steadily, with daytime highs reaching up to 23 degrees Celsius. Summer months June to August bring warm days with average highs around 26-33 degrees Celsius, but the mercury rarely drops below 9 degrees at night. Autumn is mild, with September averaging a comfortable 16 degrees Celsius, although October and November can see temperatures dip again. Winters return in December, with temperatures ranging from -10 to 13 degrees Celsius.