Japanese Weather Symbols (Tenki Kigō): Forecast Icons and Map Signs

The core idea: every symbol answers how much

Japanese weather symbols look like a random set of pictures until you notice that each one measures something. The forecast connectors measure time: how much of the period is affected. Kōsui kakuritsu measures likelihood. The weather-map circle measures sky: the Japan Meteorological Agency counts cloud cover in tenths, and the circle is drawn emptier or fuller to match. Wind feathers measure force. Keep asking how much, and each new symbol slots into place.

Start with the words. Hare (晴れ), from hareru, to clear up, is fair weather, and it covers a surprisingly cloudy sky: anything from two to eight tenths. Kaisei (快晴), literally pleasant clear, is one tenth or less; the agency uses it for observations but not in forecast text. Kumori (曇り), from kumoru, is nine tenths or more with nothing falling. Neighbours say all three at the bus stop.

Forecast icons: the basic pictures

Icons differ between providers, so learn them by idea rather than by drawing. A sun is hare and a grey cloud is kumori. Rain is shown as an umbrella on the agency's site and on the big Japanese weather portals, where many Western apps would draw raindrops. Snow is a snowman on the agency's site and a snowman or snowflake elsewhere. Behind each icon the agency keeps a code number: 100 for fair, 200 for cloudy, 300 for rain and 400 for snow, the first digit giving the main weather.

Everyday weather words, and following a spoken TV forecast, have their own guides; this one is about reading the symbols. Two colleagues checking a phone in the morning sound like this.

Nochi, tokidoki and ichiji: the grammar between two icons

A forecast line is a small sentence: main weather, connector, second weather. The connector says how the period is shared out, and the agency defines each one. Nochi (のち), later, means the weather changes partway through: hare nochi kumori, sunny then cloudy. Tokidoki (時々), sometimes, means the second weather comes and goes, with breaks of an hour or more, adding up to less than half the period. Ichiji (一時), literally one time, means a single continuous spell shorter than a quarter of the period.

Icons show this in two ways. An arrow between two equal pictures means nochi. A large picture with a small one tucked beside it means tokidoki or ichiji, and on the agency's own icons those two look exactly the same, so the words carry the difference. Connectors can combine: hare nochi tokidoki kumori is sunny, later on-and-off cloud.

UnihongoVocabulary

明日あしたは曇りくもり時々ときどき雨あめでしょう。Tomorrow will be cloudy with occasional rain.

Percentages and temperatures on the forecast screen

Kōsui kakuritsu (降水確率), literally falling-water probability, is the chance that at least 1 millimetre of rain or snow falls in a set period: six-hour blocks such as 06-12 and 12-18 in daily forecasts, whole days in the weekly one. It comes in steps of ten, and 0% means under 5%. Thirty percent means that on about thirty of a hundred occasions with that forecast, a millimetre or more fell. It says nothing about how hard or how long it rains.

In the agency's forecasts the two temperatures have their own clocks. Saikō kion (最高気温), the high, is the maximum between 9 a.m. and 6 p.m. Saitei kion (最低気温), the low, is the minimum between midnight and 9 a.m., so it is the next morning's chill, not the evening's. Many sites add zenjitsu-sa, the difference from the day before, as a plus or minus figure in brackets.

Beyond the basics: the weather-map circles, tenki kigō

Tenki kigō (天気記号), literally weather marks, are the symbols of the Japanese-style weather map taught in middle-school science and printed in newspapers. Everything grows from one circle at each observation point. Empty means kaisei. A vertical line means hare. A second, inner ring means kumori. Fill it black and it rains. This is the organising idea in miniature: the more sky is covered, the fuller the circle.

Other symbols modify the circle: six spokes for snow, a black dot in the centre for fog, a black lower half for thunder, and that half with a V above it for mizore, sleet. A small katakana beside a symbol adjusts it: tsu for tsuyoshi, heavy, ni for niwaka, showery, and ki beside a black circle for kirisame, drizzle. Niwaka ame is literally sudden rain, and kirisame is literally mist rain.

UnihongoVocabulary

快晴かいせいの記号きごうは、ただの丸まるです。The symbol for clear skies is just a circle.

Wind lines and the radio weather report

Wind is drawn as a line from the circle towards the direction the wind comes from, one of sixteen compass points, so a north wind is a line straight up. Feathers at the far end give the force, fūryoku, on the agency's scale from 0 to 12: one feather per step, up to six on one side, then more on the other. Calm gets no line.

These maps begin as sound. NHK AM radio broadcasts a daily weather report, kishō tsūhō, mainly for fishing boats, reading each station in a fixed order: place, wind direction, force, weather, pressure, temperature. Students draw maps from it in science class. Pressure is read as two digits, so 08 means 1008 hectopascals.

Common mistakes with Japanese weather symbols

Reading the double circle as excellent. In school marking and on menus, nijūmaru means top marks, so learners assume good weather. On a weather map it means kumori, overcast.

Reading every circle as fine weather. In daily life maru means correct or good, and the empty circle is indeed the best weather, kaisei; but hare needs its vertical line, and a map full of lined circles can still be fairly cloudy.

Hearing tokidoki as maybe. English sometimes can express doubt, but tokidoki describes timing, not probability. The doubt lives in kōsui kakuritsu.

Taking 30% as light rain, or rain for 30% of the day. The figure is only the chance of reaching 1 millimetre in that block.

Drawing the wind line pointing downwind. Arrows on most maps show where things move, so learners draw the line downwind. The Japanese wind line points into the wind, towards its source.