Longmont's winters are harsh, with temperatures often dropping below freezing and averaging around -4°C in January. Spring brings a slow warming trend, with March temperatures hovering near 0°C and April seeing averages of 2°C. Summers are warm to hot, with June and July temperatures frequently reaching the mid-30s Celsius and averaging around 16-18°C. Autumn is mild, with September's average temperature still above 10°C before dropping back down in October and November. Winters return with cold snaps and brief periods of warmth, but overall remain chilly, especially from December to February.