Average Weather at Iruma Ab Japan
At Iruma Ab, the summers are short, warm, oppressive, wet, and mostly cloudy and the winters are very cold and mostly clear. Over the course of the year, the temperature typically varies from 30°F to 87°F and is rarely below 24°F or above 95°F.
Based on the beach/pool score, the best time of year to visit Iruma Ab for hot-weather activities is from late July to early September.
The hot season lasts for 2.6 months, from June 27 to September 15, with an average daily high temperature above 79°F. The hottest day of the year is August 7, with an average high of 87°F and low of 74°F.
The cold season lasts for 3.5 months, from December 2 to March 18, with an average daily high temperature below 55°F. The coldest day of the year is January 21, with an average low of 30°F and high of 47°F.
Average High and Low Temperature
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.
Average Hourly Temperature
At Iruma 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 Iruma Ab begins around October 7 and lasts for 5.8 months, ending around March 31. On December 27, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 76% of the time, and overcast or mostly cloudy 24% of the time.
The cloudier part of the year begins around March 31 and lasts for 6.2 months, ending around October 7. On July 2, the cloudiest day of the year, the sky is overcast or mostly cloudy 73% of the time, and clear, mostly clear, or partly cloudy 28% of the time.
Cloud Cover Categories
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days at Iruma Ab varies significantly throughout the year.
The wetter season lasts 6.7 months, from March 23 to October 13, with a greater than 30% chance of a given day being a wet day. The chance of a wet day peaks at 50% on June 24.
The drier season lasts 5.3 months, from October 13 to March 23. The smallest chance of a wet day is 10% on December 30.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 50% on June 24.
Daily Chance of Precipitation
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. Iruma Ab experiences extreme seasonal variation in monthly rainfall.
Rain falls throughout the year at Iruma Ab. The most rain falls during the 31 days centered around September 20, with an average total accumulation of 7.3 inches.
The least rain falls around January 1, with an average total accumulation of 1.3 inches.
Average Monthly Rainfall
The sliding 31-day liquid-equivalent quantity of snowfall at Iruma Ab does not vary significantly over the course of the year, staying within 0.1 inches of 0.1 inches throughout.
Average Liquid-Equivalent Monthly Snowfall
The length of the day at Iruma Ab varies significantly over the course of the year. In 2018, the shortest day is December 22, with 9 hours, 44 minutes of daylight; the longest day is June 21, with 14 hours, 36 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 4:25 AM on June 13, and the latest sunrise is 2 hours, 28 minutes later at 6:53 AM on January 7. The earliest sunset is at 4:28 PM on December 6, and the latest sunset is 2 hours, 34 minutes later at 7:02 PM on June 29.
Daylight saving time (DST) is not observed at Iruma Ab during 2018.
Sunrise & Sunset with Twilight
Iruma Ab experiences extreme seasonal variation in the perceived humidity.
The muggier period of the year lasts for 3.5 months, from June 11 to September 28, during which time the comfort level is muggy, oppressive, or miserable at least 23% of the time. The muggiest day of the year is August 8, with muggy conditions 93% of the time.
The least muggy day of the year is February 13, when muggy conditions are essentially unheard of.
Humidity Comfort Levels
The average hourly wind speed at Iruma Ab experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 4.8 months, from December 23 to May 18, with average wind speeds of more than 7.3 miles per hour. The windiest day of the year is March 25, with an average hourly wind speed of 8.3 miles per hour.
The calmer time of year lasts for 7.2 months, from May 18 to December 23. The calmest day of the year is August 1, with an average hourly wind speed of 6.3 miles per hour.
Average Wind Speed
The predominant average hourly wind direction at Iruma Ab varies throughout the year.
The wind is most often from the north for 3.1 months, from January 13 to April 15 and for 2.9 months, from September 17 to December 13, with a peak percentage of 50% on February 24. The wind is most often from the south for 4.7 months, from April 15 to September 7, with a peak percentage of 45% on July 24. The wind is most often from the west for 1.0 months, from December 13 to January 13, with a peak percentage of 45% on January 1.
Iruma 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 significant seasonal variation over the course of the year.
The time of year with warmer water lasts for 2.5 months, from July 14 to September 29, with an average temperature above 74°F. The day of the year with the warmest water is August 18, with an average temperature of 79°F.
The time of year with cooler water lasts for 4.0 months, from December 25 to April 25, with an average temperature below 61°F. The day of the year with the coolest water is February 24, with an average temperature of 57°F.
Average Water Temperature
Best Time of Year to Visit
To characterize how pleasant the weather is at Iruma 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 Iruma Ab for general outdoor tourist activities is from late July to early October, with a peak score in the first 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 Iruma Ab for hot-weather activities is from late July to early September, with a peak score in the second week of August.
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.
The growing season at Iruma Ab typically lasts for 8.5 months (260 days), from around March 21 to around December 6, rarely starting before March 3 or after April 8, and rarely ending before November 18 or after December 23.
Time Spent in Various Temperature Bands and the Growing Season
Based on growing degree days alone, the first spring blooms at Iruma Ab should appear around April 2, only rarely appearing before March 22 or after April 14.
Growing Degree Days
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 12 to August 27, with an average daily incident shortwave energy per square meter above 5.3 kWh. The brightest day of the year is May 22, with an average of 5.9 kWh.
The darker period of the year lasts for 3.1 months, from November 1 to February 4, with an average daily incident shortwave energy per square meter below 3.3 kWh. The darkest day of the year is December 20, with an average of 2.6 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Iruma Ab are 35.842 deg latitude, 139.411 deg longitude, and 249 ft elevation.
The topography within 2 miles of Iruma Ab contains only modest variations in elevation, with a maximum elevation change of 322 feet and an average elevation above sea level of 258 feet. Within 10 miles contains only modest variations in elevation (1,532 feet). Within 50 miles contains very significant variations in elevation (10,764 feet).
The area within 2 miles of Iruma Ab is covered by artificial surfaces (60%), cropland (23%), and trees (12%), within 10 miles by artificial surfaces (40%) and cropland (29%), and within 50 miles by trees (42%) and cropland (27%).
This report illustrates the typical weather at Iruma Ab, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
Iruma Ab has a weather station that reported reliably enough during the analysis period that we have included it in our network. When available, historical temperature and dew point measurements are taken directly from this weather station. These records are obtained from NOAA's Integrated Surface Hourly data set, falling back on ICAO METAR records as required.
In the case of missing or erroneous measurements from this station, we fall back on records from nearby stations, adjusted according to typical seasonal and diurnal intra-station differences. For a given day of the year and hour of the day, the fallback station is selected to minimize the prediction error over the years for which there are measurements for both stations.
The stations on which we may fall back include but are not limited to Yokota Air Base, Tokyo, Atsugi United States Naval Air Station, Tokyo International Airport, Shimofusa Ab, Yokosuka Fwf, Tateyama Ab, and Narita International Airport.
Time zones for aiports and weather stations are provided by AskGeo.com .