The climatic range is greater than the limited size of the peninsula would suggest. The average January temperature is -17° C (1° F ) at Chunggang on the north-central border and -8° C (18° F ) at P'yongyang. In the hottest part of the summer, however, the variation is not nearly so marked, average temperatures ranging from 24° C (75° F ) in P'yongyang to 21° C (70° F ) along the relatively cool northeast coast. Spring and fall are unusually pleasant, but winters are colder than average for the latitude, and summers are hot and humid. Precipitation is around 50 cm (20 in) along the upper reaches of the Tumen, but more than half of the peninsula receives 75–100 cm (30–40 in) per year. Nearly all the rainfall occurs in the April–September period, especially during the rainy season, from late June to early August. Typhoons occur occasionally in the early fall. Days without frost number about 180 in the northern part of the peninsula and increase toward the south.