How to talk about change in Japanese — one forecast at a time

Japan Times

29-05-2025

As we head into June, 天気 (tenki, weather) will be an increasingly frequent topic for small talk — especially during 梅雨 (tsuyu, rainy season). This period of 雨 (ame, rain) and 湿気 (shikke, humidity) usually continues for a month or so until mid-July.
梅雨 also means it's time for 衣替え (koromogae), the term used to refer to a seasonal change of clothes that sees us put the sweaters away and bring out the T-shirts.
学校の制服などの衣替えは、6月に冬服から夏服へ、10月にまた冬服へ切り替えるのが一般的です (Gakkō no seifuku nado no koromogae wa, rokugatsu ni fuyufuku kara natsufuku e, jūgatsu ni mata fuyufuku e kirikaeru noga ippan-teki desu, It's common for schools to switch their uniforms from winter to summer versions in June, and switch back to winter uniforms in October).
General changes are usually indicated by the kanji 変 (hen, ka[eru], ka[waru]), which is also used in the noun 変化 (henka, change). However, the word 衣替え uses the kanji 替 (tai, ka[eru], ka[waru]) instead of the more common 変. Also representing change, 替 is more suitable when describing a switch between limited options such as 着替え (kigae, change of clothes) and 両替 (ryōgae, money exchange).
As the 最高気温 (saikō kion, high temperature) of the day begins to rise, wardrobe changes from 長袖 (nagasode, long sleeves) to 半袖 (hansode, half sleeves) are unavoidable. 気温が上がるにつれて、薄着で過ごす日が増えます (Kion ga agaru ni tsurete, usugi de sugosu hi ga fuemasu, As the temperature rises, there are more days when [we] dress lightly).
The grammatical structure ～につれて (~ni tsurete) regularly pops up in weather forecasts when describing gradual changes in multiple things. The structure ～にしたがって (~ni shitagatte) works similarly, and both terms loosely translate to 'as~,' 'in accordance with~' or 'consequently.' When you want to point out two things that are changing, put a noun or a noun clause in front of one of these components, and add additional information about the subsequent incident after them.
This may sound tricky, but it might sound familiar when phrased like this: 勉強するにつれてさらに難しい文法が出てくる (Benkyō suru ni tsurete sarani muzukashii bunpō ga dete kuru, As [I] study more, more difficult grammar comes up) or 昇進するにしたがって仕事の責任が重くなる (Shōshin suru ni shitagatte shigoto no sekinin ga omoku naru, As [I] get promoted, the job responsibilities become greater).
The good news is that these two components are often interchangeable. That said, their nuance can be slightly different depending on the situation. ～にしたがって is more formal and suited to written Japanese, sometimes putting more focus on a consequence that stems from the initial event.
～につれて explains two events linked in a more natural and passive manner, and it works well in conversation.
When we explain the link between weather and clothes, though, both structures sound correct. For example, the earlier example can be rephrased as 気温が上がるにしたがって、薄着で過ごす日が増えます (Kion ga agaru ni shitagatte, usugi de sugosu hi ga fuemasu) and maintain the same meaning — as the temperature rises, we wear light clothes.
However, if you are attending a business meeting and say, 売上の増加にしたがって店舗も増やさなくてはいけない (Uriage no zōka ni shitagatte tenpo mo fuyasanakute wa ikenai, As sales grow, [the number of] stores should be increased), it'll sound off if you opt to use ～につれて.
That's because つれて comes from the verb 連れる (tsureru, to bring along), while the core verb of したがって is 従う (shitagau, to obey [to follow]). Thus, if the resulting event is intentional — like increasing the number of stores — したがって will sound more correct.
As for weather, we normally follow the meteorologist's advice: 天気予報にしたがって洋服を選ぶ (Tenki yohō ni shitagatte yōfuku o erabu, Follow the weather forecast and choose clothes).
In order to be appropriately dressed when the weather is unstable, our activities during the 衣替え period can make a big difference. Here are some tips:
不要な服は処分し、その他の服は洗濯やクリーニングをしましょう (Fuyōna fuku wa shobun shi, sono ta no fuku wa sentaku ya kurīningu o shimashō, Dispose of clothes no longer needed, and wash or dry-clean the rest)
次のシーズンに探しやすいよう、季節や種類にしたがってまとめましょう (Tsugi no shīzun ni sagashiyasui yō, kisetsu ya shurui ni shitagatte matomemashō, Sort and group clothes according to season and type to keep them easy to locate next season)
服の種類や生地に合わせて、シワやカビにならないように収納しましょう (Fuku no shurui ya kiji ni awasete, shiwa ni naranai yōni shūnō shimashō, Store clothes properly based on their type and fabric to prevent wrinkles and mold)
湿度の高い場所には防虫剤や除湿剤を置き、定期的に交換しましょう (Shitsudo no takai basho niwa bōchūzai ya joshitsuzai o oki, teiki-teki ni kōkan shimashō, In humid places, put bug repellents and moisture absorbers and replace them regularly)
これから着たい服を手前に、季節外れの服を奥にしまいましょう (Korekara kitai fuku o temae ni, kisetsu hazure no fuku o oku ni shimaimashō, Put upcoming seasonal clothes at the front and store off-season clothes in the back)