Climate Type and Basic Characteristics
Nantong City has a subtropical monsoon climate (some sources refer to it as the northern subtropical monsoon climate zone). It has distinct four seasons, with rain and heat occurring in the same seasons, and a strong maritime climate. The average annual temperature is approximately 15°C (15.9°C in Haimen District). Annual precipitation is 1,000-1,100 mm, with summer accounting for 40%-50%.
Seasonal Characteristics
Spring (March-May)
Frequent alternations of cold and warm air, unstable temperature rises, and frequent low-temperature, continuous rainy spells and spring frosts. The weather is changeable, with gradually increasing precipitation.
Summer (June-August)
Plum Rain Season: From mid-June to mid-July, precipitation is concentrated, with little sunshine and overcast weather. The average plum rain season lasts 25 days.
Midsummer: After the plum rain season, the city is controlled by subtropical high pressure, with sunny, hot, and high temperatures, with extreme temperatures reaching 39.7°C (in Haimen District). Typhoons frequently occur (an average of 2.9 per year), accompanied by severe convective weather such as thunderstorms, strong winds, and short bursts of heavy rainfall. Autumn (September-November)
Cold air activity intensifies, with temperatures dropping faster than they rise in spring. The weather is often clear and crisp, with less precipitation and abundant sunshine, making it ideal for the autumn harvest.
Winter (December-February)
Dry and cold with little rain or snow. Northwest winds prevail, with an average of 2-3 cold waves annually. Extreme lows reach -9.4°C (Haimen District). Precipitation accounts for only 11% of the annual total, making it the driest season.
Extreme Weather and Disasters
High Temperatures: Extreme summer temperatures can reach 40°C ( For example, the Nantong Station in 2022.）Haimen District experienced a high temperature of 39.5°C in 2024.
Heavy Rainfall: Summer rainstorms are frequent, with the maximum daily rainfall reaching 592.3 mm (in Haimen District in June 2015), which can easily cause flooding.
Typhoons and Severe Convection: Typhoons bring strong winds and heavy rain upon landfall, and hail may occur in some areas.
Other Characteristics:
Long frost-free period: Suitable for a double-cropping system, with triple-cropping possible in riverside areas.
Fog Days: Frequent in spring, peaking in April, and often occurring in the early morning to mid-morning.
Nantong's climate combines monsoonal and maritime characteristics, with abundant water and heat resources. However, meteorological disasters (such as typhoons, high temperatures, and heavy rain) have significant impacts on agriculture and urban management.