Climate and Average Weather Year Round at Tateyama Ab Japan

At Tateyama Ab, the summers are short, warm, oppressive, and mostly cloudy; the winters are cold, windy, and mostly clear; and it is wet year round. Over the course of the year, the temperature typically varies from 38°F to 85°F and is rarely below 31°F or above 90°F.

Based on the beach/pool score, the best time of year to visit Tateyama Ab for hot-weather activities is from late July to early September.

The hot season lasts for 2.7 months, from June 30 to September 20, with an average daily high temperature above 78°F. The hottest month of the year at Tateyama Ab is August, with an average high of 85°F and low of 75°F.

The cool season lasts for 3.4 months, from December 8 to March 20, with an average daily high temperature below 57°F. The coldest month of the year at Tateyama Ab is January, with an average low of 39°F and high of 51°F.

At Tateyama Ab, 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 at Tateyama Ab begins around September 29 and lasts for 6.1 months, ending around April 1.

The clearest month of the year at Tateyama Ab is December, during which on average the sky is clear, mostly clear, or partly cloudy 74% of the time.

The cloudier part of the year begins around April 1 and lasts for 5.9 months, ending around September 29.

The cloudiest month of the year at Tateyama Ab is June, during which on average the sky is overcast or mostly cloudy 71% 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 Tateyama Ab varies significantly throughout the year.

The wetter season lasts 7.7 months, from March 5 to October 28, with a greater than 34% chance of a given day being a wet day. The month with the most wet days at Tateyama Ab is June, with an average of 13.9 days with at least 0.04 inches of precipitation.

The drier season lasts 4.3 months, from October 28 to March 5. The month with the fewest wet days at Tateyama Ab is January, 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 Tateyama Ab is June, with an average of 13.9 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 23.

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. Tateyama Ab experiences extreme seasonal variation in monthly rainfall.

Rain falls throughout the year at Tateyama Ab. The month with the most rain at Tateyama Ab is September, with an average rainfall of 7.7 inches.

The month with the least rain at Tateyama Ab is January, with an average rainfall of 2.5 inches.

The length of the day at Tateyama Ab varies significantly over the course of the year. In 2024, the shortest day is December 21, with 9 hours, 48 minutes of daylight; the longest day is June 21, with 14 hours, 31 minutes of daylight.

The earliest sunrise is at 4:26 AM on June 12, and the latest sunrise is 2 hours, 23 minutes later at 6:49 AM on January 8. The earliest sunset is at 4:28 PM on December 5, and the latest sunset is 2 hours, 30 minutes later at 6:58 PM on June 29.

Daylight saving time (DST) is not observed at Tateyama Ab during 2024.

The figure below presents a compact representation of key lunar data for 2024. 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.

Tateyama Ab experiences extreme seasonal variation in the perceived humidity.

The muggier period of the year lasts for 4.3 months, from May 30 to October 7, during which time the comfort level is muggy, oppressive, or miserable at least 24% of the time. The month with the most muggy days at Tateyama Ab is August, with 29.3 days that are muggy or worse.

The month with the fewest muggy days at Tateyama Ab is February, 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 at Tateyama Ab experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 7.6 months, from September 23 to May 9, with average wind speeds of more than 11.1 miles per hour. The windiest month of the year at Tateyama Ab is February, with an average hourly wind speed of 12.8 miles per hour.

The calmer time of year lasts for 4.4 months, from May 9 to September 23. The calmest month of the year at Tateyama Ab is August, with an average hourly wind speed of 9.3 miles per hour.

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

The wind is most often from the south for 5.0 months, from April 10 to September 11, with a peak percentage of 49% on August 8. The wind is most often from the east for 1.7 weeks, from September 11 to September 23, with a peak percentage of 33% on September 15. The wind is most often from the north for 6.6 months, from September 23 to April 10, with a peak percentage of 50% on January 1.

Tateyama Ab 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 2.6 months, from July 16 to October 4, with an average temperature above 75°F. The month of the year at Tateyama Ab with the warmest water is August, with an average temperature of 79°F.

The time of year with cooler water lasts for 3.9 months, from December 29 to April 25, with an average temperature below 64°F. The month of the year at Tateyama Ab with the coolest water is February, with an average temperature of 60°F.

To characterize how pleasant the weather is at Tateyama Ab 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 Tateyama Ab for general outdoor tourist activities is from late July to late October, with a peak score in the last week of September.

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 Tateyama Ab for hot-weather activities is from late July to early September, with a peak score in the second 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 at Tateyama Ab typically lasts for 10 months (305 days), from around February 24 to around December 26, rarely starting before February 5 or after March 16, and rarely ending before December 11 or after January 10.

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 at Tateyama Ab should appear around March 10, only rarely appearing before February 24 or after March 26.

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 4.5 months, from April 14 to August 29, with an average daily incident shortwave energy per square meter above 5.4 kWh. The brightest month of the year at Tateyama Ab is July, with an average of 5.9 kWh.

The darker period of the year lasts for 3.2 months, from October 31 to February 4, with an average daily incident shortwave energy per square meter below 3.3 kWh. The darkest month of the year at Tateyama Ab is December, with an average of 2.7 kWh.

For the purposes of this report, the geographical coordinates of Tateyama Ab are 34.987 deg latitude, 139.829 deg longitude, and 13 ft elevation.

The topography within 2 miles of Tateyama Ab contains only modest variations in elevation, with a maximum elevation change of 463 feet and an average elevation above sea level of 61 feet. Within 10 miles contains only modest variations in elevation (1,158 feet). Within 50 miles contains very significant variations in elevation (4,846 feet).

The area within 2 miles of Tateyama Ab is covered by water (73%) and trees (20%), within 10 miles by water (70%) and trees (22%), and within 50 miles by water (79%) and trees (11%).