Climate and Average Weather Year Round at Chichijima Japan

At Chichijima, the summers are long, warm, oppressive, wet, and mostly cloudy; the winters are comfortable and mostly clear; and it is windy year round. Over the course of the year, the temperature typically varies from 61°F to 85°F and is rarely below 56°F or above 88°F.

Based on the tourism score, the best time of year to visit Chichijima for warm-weather activities is from late October to early April.

The hot season lasts for 4.2 months, from June 15 to October 20, with an average daily high temperature above 82°F. The hottest month of the year at Chichijima is August, with an average high of 85°F and low of 79°F.

The cool season lasts for 3.1 months, from December 21 to March 26, with an average daily high temperature below 71°F. The coldest month of the year at Chichijima is February, with an average low of 61°F and high of 68°F.

At Chichijima, the average percentage of the sky covered by clouds experiences extreme seasonal variation over the course of the year.

The clearer part of the year at Chichijima begins around September 26 and lasts for 6.6 months, ending around April 13.

The clearest month of the year at Chichijima is February, 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 April 13 and lasts for 5.4 months, ending around September 26.

The cloudiest month of the year at Chichijima is June, during which on average the sky is overcast or mostly cloudy 78% 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 at Chichijima varies throughout the year.

The wetter season lasts 11 months, from July 23 to June 14, with a greater than 30% chance of a given day being a wet day. The month with the most wet days at Chichijima is May, with an average of 12.0 days with at least 0.04 inches of precipitation.

The drier season lasts 1.3 months, from June 14 to July 23. The month with the fewest wet days at Chichijima is February, with an average of 6.0 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 at Chichijima is May, with an average of 12.0 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 43% on May 24.

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. Chichijima experiences extreme seasonal variation in monthly rainfall.

Rain falls throughout the year at Chichijima. The month with the most rain at Chichijima is May, with an average rainfall of 5.7 inches.

The month with the least rain at Chichijima is January, with an average rainfall of 1.8 inches.

The length of the day at Chichijima varies over the course of the year. In 2025, the shortest day is December 22, with 10 hours, 26 minutes of daylight; the longest day is June 21, with 13 hours, 51 minutes of daylight.

The earliest sunrise is at 4:36 AM on June 10, and the latest sunrise is 1 hour, 46 minutes later at 6:22 AM on January 12. The earliest sunset is at 4:37 PM on November 30, and the latest sunset is 1 hour, 53 minutes later at 6:29 PM on July 2.

Daylight saving time (DST) is not observed at Chichijima 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.

Chichijima experiences extreme seasonal variation in the perceived humidity.

The muggier period of the year lasts for 8.3 months, from March 28 to December 7, during which time the comfort level is muggy, oppressive, or miserable at least 29% of the time. The month with the most muggy days at Chichijima is August, with 31.0 days that are muggy or worse.

The month with the fewest muggy days at Chichijima is January, with 1.9 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 at Chichijima experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 6.5 months, from October 6 to April 22, with average wind speeds of more than 13.0 miles per hour. The windiest month of the year at Chichijima is January, with an average hourly wind speed of 15.9 miles per hour.

The calmer time of year lasts for 5.5 months, from April 22 to October 6. The calmest month of the year at Chichijima is June, with an average hourly wind speed of 10.5 miles per hour.

The predominant average hourly wind direction at Chichijima varies throughout the year.

The wind is most often from the north for 1.7 months, from February 5 to March 26 and for 2.3 months, from November 20 to January 28, with a peak percentage of 37% on February 8. The wind is most often from the east for 1.5 months, from March 26 to May 9 and for 4.3 months, from July 11 to November 20, with a peak percentage of 55% on September 28. The wind is most often from the south for 2.1 months, from May 9 to July 11, with a peak percentage of 49% on June 13.

Chichijima 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 some seasonal variation over the course of the year.

The time of year with warmer water lasts for 4.0 months, from June 26 to October 27, with an average temperature above 80°F. The month of the year at Chichijima with the warmest water is August, with an average temperature of 82°F.

The time of year with cooler water lasts for 3.6 months, from January 5 to April 23, with an average temperature below 72°F. The month of the year at Chichijima with the coolest water is February, with an average temperature of 69°F.

To characterize how pleasant the weather is at Chichijima 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 Chichijima for general outdoor tourist activities is from late October to early April, with a peak score in the last week of November.

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 Chichijima for hot-weather activities is from late August to mid November, with a peak score in the third week of October.

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).

Temperatures at Chichijima are sufficiently warm year round that it is not entirely meaningful to discuss the growing season in these terms. We nevertheless include the chart below as an illustration of the distribution of temperatures experienced throughout the year.

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.

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 significant seasonal variation over the course of the year.

The brighter period of the year lasts for 1.7 months, from June 3 to July 26, with an average daily incident shortwave energy per square meter above 5.7 kWh. The brightest month of the year at Chichijima is June, with an average of 6.1 kWh.

The darker period of the year lasts for 2.5 months, from November 14 to January 30, with an average daily incident shortwave energy per square meter below 3.8 kWh. The darkest month of the year at Chichijima is December, with an average of 3.2 kWh.

For the purposes of this report, the geographical coordinates of Chichijima are 27.083 deg latitude, 142.183 deg longitude, and 0 ft elevation.

The topography within 2 miles of Chichijima contains significant variations in elevation, with a maximum elevation change of 787 feet and an average elevation above sea level of 63 feet. Within 10 miles contains significant variations in elevation (1,047 feet). Within 50 miles also contains very significant variations in elevation (1,440 feet).

The area within 2 miles of Chichijima is covered by water (79%) and trees (13%), within 10 miles by water (97%), and within 50 miles by water (100%).