The best time to visit to Japan

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Climate notes

Maximum temperature

The average maximum day temperature gives a good indication of the highest temperatures to expect at the warmest time of the day for each month. Because the figures show the temperature of the air, they are always recorded in the shade. In direct sun it will generally be warmer, sometimes by as much as 15 to 20C (27 to 36F). This is because the sun also emits infrared radiation. For tropical and some sub-tropical destinations, be sure to check humidity, because high temperatures alone do not necessarily indicate how hot it 'feels'.

Minimum temperature

The average minimum night temperature gives a good indication of the lowest temperatures to expect during the night for each month. In some places it can become relatively cold at night, like at high elevations and in desert areas.

Sunshine hours

This shows the average number of hours of bright sunshine per day for each month, rounded to the nearest hour. Sunshine hours should always be viewed relative to the number of hours of daylight there are in the day, which gives an idea of the percentage of daylight hours that have bright sunshine.

Daylight hours

This shows the number of daylight hours for the middle day of each month. Since the earth is tilted on its axis, the further you travel away from the equator, the more variable day length can become. Within the Arctic and Antarctic circles, this extends to days with no daylight or permanent daylight depending on the time of year.

Rainfall

This shows the average monthly rainfall in millimetres and inches for each month. High levels of rainfall do not necessarily indicate poor weather conditions, as many places in the tropics have high levels of rainfall and lots of sunshine as well. The Maldives, for example, has more than twice the rainfall of Manchester but also has more than twice the amount of sunshine. Combining Average Number of Rainy Days with Rainfall you can build up an idea of both the frequency and amount of rainfall.

Rainy days

This shows the average number of days for each month when a measurable amount (defined as 0.1mm) of rain falls. This includes precipitation that may fall as snow in areas where it is cold enough. This statistic does not imply that it rains throughout the day; it merely shows the number of days in the month when some rain is recorded - a useful indicator of the frequency of rainfall. In conjunction with Average Monthly Rainfall amount you can build up an idea of both the frequency and amount of rainfall.

Humidity

This gives an indication of average levels of discomfort caused by high temperatures combined with high humidity. High temperatures alone do not necessarily indicate how hot it 'feels', because high levels of humidity in the air also play a role. As the air temperature approaches body temperature (37C / 98F) in humid conditions, the body's ability to cool itself by perspiring becomes impaired. The result is a feeling of discomfort.

The higher the level of heat and humidity the more uncomfortable you are likely to feel. Humidity is not an issue at temperatures below about 24C (75F), no matter how high the humidity.

Heat & humidity key
N: None
L: Low
M: Moderate
H: High
VH: Very high
E: Extreme

UV

The UV index gives an indication of how strong UV radiation may be at its maximum; that is, under clear sky conditions around midday. This shows the potential for skin damage through exposure to the sun at the most dangerous time of the day. The UV index is measured on the Global Solar UV Index (UVI) scale.

The World Health Organisation recommends protective measures be taken for all UV values over 2.

UV key
N: None
L: Low
M: Moderate
H: High
VH: Very high
E: Extreme

Sea temperature

Average sea temperature shows average monthly sea-surface temperatures for each month rounded to the nearest degree. As a general rule, travellers consider that water is cold to cool at 18-24C (65-75F), comfortable at 24-28C (75-82F), and warm at 28C or more (82F or more). Because the sun also emits infra-red radiation, swimming in the sea in direct sun can help to improve the sensation of cooler water temperatures.