Flagstaff's winters are extremely cold, with temperatures often below freezing and averaging just a few degrees above zero. Spring brings mild temperatures, gradually warming up throughout the month of April and May, with average highs reaching into the mid-teens Celsius by late spring. Summer is warm but not hot, with July and August averaging around 23°C, while September cools down slightly. Autumn sees a return to chilly weather, with temperatures dropping back down into single digits by November, similar to winter conditions. Overall, Flagstaff's climate is relatively cool year-round, with moderate temperature fluctuations between seasons.