Climate and Average Weather Year Round in Xihu China

In Xihu, the summers are short, hot, oppressive, wet, and mostly cloudy and the winters are very cold and partly cloudy. Over the course of the year, the temperature typically varies from 33°F to 93°F and is rarely below 26°F or above 99°F.

Based on the tourism score, the best time of year to visit Xihu for warm-weather activities is from mid September to mid October.

The hot season lasts for 2.9 months, from June 14 to September 10, with an average daily high temperature above 83°F. The hottest month of the year in Xihu is July, with an average high of 91°F and low of 78°F.

The cool season lasts for 3.1 months, from December 3 to March 6, with an average daily high temperature below 55°F. The coldest month of the year in Xihu is January, with an average low of 34°F and high of 46°F.

In Xihu, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.

The clearer part of the year in Xihu begins around September 2 and lasts for 6.3 months, ending around March 12.

The clearest month of the year in Xihu is October, during which on average the sky is clear, mostly clear, or partly cloudy 70% of the time.

The cloudier part of the year begins around March 12 and lasts for 5.7 months, ending around September 2.

The cloudiest month of the year in Xihu is July, during which on average the sky is overcast or mostly cloudy 70% of the time.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Xihu varies significantly throughout the year.

The wetter season lasts 6.7 months, from February 19 to September 11, with a greater than 32% chance of a given day being a wet day. The month with the most wet days in Xihu is June, with an average of 13.4 days with at least 0.04 inches of precipitation.

The drier season lasts 5.3 months, from September 11 to February 19. The month with the fewest wet days in Xihu is December, with an average of 5.2 days with at least 0.04 inches of precipitation.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. The month with the most days of rain alone in Xihu is June, with an average of 13.4 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 50% on June 22.

Rainfall

To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Xihu experiences extreme seasonal variation in monthly rainfall.

Rain falls throughout the year in Xihu. The month with the most rain in Xihu is June, with an average rainfall of 7.6 inches.

The month with the least rain in Xihu is December, with an average rainfall of 1.4 inches.

Snowfall

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Xihu experiences some seasonal variation in monthly snowfall.

The snowy period of the year lasts for 1.8 months, from December 29 to February 20, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow in Xihu is January, with an average snowfall of 1.8 inches.

The snowless period of the year lasts for 10 months, from February 20 to December 29. The least snow falls around July 20, with an average total accumulation of 0.0 inches.

The length of the day in Xihu varies significantly over the course of the year. In 2025, the shortest day is December 21, with 10 hours, 12 minutes of daylight; the longest day is June 21, with 14 hours, 6 minutes of daylight.

The earliest sunrise is at 4:57 AM on June 11, and the latest sunrise is 2 hours, 0 minutes later at 6:57 AM on January 10. The earliest sunset is at 4:58 PM on December 2, and the latest sunset is 2 hours, 7 minutes later at 7:05 PM on June 30.

Daylight saving time (DST) is not observed in Xihu during 2025.

The figure below presents a compact representation of key lunar data for 2025. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases.

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

Xihu experiences extreme seasonal variation in the perceived humidity.

The muggier period of the year lasts for 4.8 months, from May 12 to October 6, during which time the comfort level is muggy, oppressive, or miserable at least 25% of the time. The month with the most muggy days in Xihu is July, with 30.6 days that are muggy or worse.

The month with the fewest muggy days in Xihu is January, with 0.0 days that are muggy or worse.

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in Xihu experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 3.5 months, from January 31 to May 15, with average wind speeds of more than 7.4 miles per hour. The windiest month of the year in Xihu is March, with an average hourly wind speed of 7.9 miles per hour.

The calmer time of year lasts for 8.5 months, from May 15 to January 31. The calmest month of the year in Xihu is June, with an average hourly wind speed of 6.8 miles per hour.

The predominant average hourly wind direction in Xihu varies throughout the year.

The wind is most often from the east for 1.0 months, from March 13 to April 13; for 3.9 weeks, from May 20 to June 16; and for 2.0 months, from August 11 to October 12, with a peak percentage of 42% on September 27. The wind is most often from the south for 1.2 months, from April 13 to May 20 and for 1.8 months, from June 16 to August 11, with a peak percentage of 48% on July 14. The wind is most often from the north for 5.0 months, from October 12 to March 13, with a peak percentage of 47% on January 1.

Xihu is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.

The average water temperature experiences significant seasonal variation over the course of the year.

The time of year with warmer water lasts for 3.3 months, from June 23 to October 1, with an average temperature above 75°F. The month of the year in Xihu with the warmest water is August, with an average temperature of 82°F.

The time of year with cooler water lasts for 3.4 months, from December 24 to April 5, with an average temperature below 52°F. The month of the year in Xihu with the coolest water is February, with an average temperature of 45°F.

To characterize how pleasant the weather is in Xihu throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit Xihu for general outdoor tourist activities is from mid September to mid October, with a peak score in the first week of October.

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Xihu for hot-weather activities is from late July to mid September, with a peak score in the last week of August.

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

The growing season in Xihu typically lasts for 9.2 months (279 days), from around February 26 to around December 2, rarely starting before February 5 or after March 17, and rarely ending before November 13 or after December 22.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

Based on growing degree days alone, the first spring blooms in Xihu should appear around March 10, only rarely appearing before February 22 or after March 29.

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy experiences some seasonal variation over the course of the year.

The brighter period of the year lasts for 1.8 months, from April 25 to June 19, with an average daily incident shortwave energy per square meter above 5.2 kWh. The brightest month of the year in Xihu is May, with an average of 5.6 kWh.

The darker period of the year lasts for 3.0 months, from November 10 to February 10, with an average daily incident shortwave energy per square meter below 3.5 kWh. The darkest month of the year in Xihu is December, with an average of 3.0 kWh.

For the purposes of this report, the geographical coordinates of Xihu are 30.242 deg latitude, 120.119 deg longitude, and 52 ft elevation.

The topography within 2 miles of Xihu contains very significant variations in elevation, with a maximum elevation change of 1,066 feet and an average elevation above sea level of 225 feet. Within 10 miles also contains very significant variations in elevation (1,765 feet). Within 50 miles contains very significant variations in elevation (5,354 feet).

The area within 2 miles of Xihu is covered by trees (69%), water (14%), and artificial surfaces (10%), within 10 miles by cropland (38%) and artificial surfaces (26%), and within 50 miles by trees (46%) and cropland (33%).