Heerlen experiences a moderate climate with cold winters and warm summers. Winters are chilly, with temperatures often below freezing from January to March, but can occasionally rise above average in February and March. Spring brings mild temperatures, gradually warming up from April to June, with May being particularly pleasant, averaging 9°C. Summers are warm but not hot, with July and August being the warmest months, averaging around 16°C, while September is slightly cooler again. Autumn is characterized by moderate temperatures, dropping off slowly from October to November, before the cold winter sets in once more.