Winters in Northglenn are cold, with temperatures often below freezing and averaging around -5°C. The coldest months are January and February, with temperatures sometimes dropping as low as -23°C. Spring brings a gradual warming trend, with temperatures rising to an average of 2°C by April and 7°C by May. Summer is warm, but not hot, with July and August averaging around 18°C. Autumn sees a return to cooler temperatures, with averages ranging from 4°C in November to -1°C in December.