猛暑日（Extremely hot day）

猛暑日とは？

「猛暑日（もうしょび）」とは、最高気温が35℃以上の日を指す気象用語です。
この言葉は2007年に気象庁が公式に定義したもので、それ以前は特に区別されていませんでした。

「猛暑日」という言葉が生まれた背景

地球温暖化の影響で極端な暑さが増えた

・1990年代後半から、夏の最高気温が35℃を超える日が増加。
・それまでの「真夏日（30℃以上）」だけでは、暑さの強さを表現しきれなくなった。

2004年の異常気象がきっかけ

・2004年の夏、全国的に記録的な猛暑が続いた。
・東京でも39.5℃（観測史上最高）を記録し、「異常な暑さ」を表す言葉が必要になった。
・その後、2007年に気象庁が正式に「猛暑日」を定義。

「猛暑日」と他の暑さの基準

猛暑日の増加と地球温暖化

猛暑日の回数は増えている

・1980年代までは猛暑日は珍しい存在だった。
・2000年代以降は毎年のように猛暑日が全国各地で観測されるようになった。
・特に、ヒートアイランド現象の影響で都市部の猛暑日が増加。

猛暑日の影響

「猛暑日」と言葉の広まり

2007年頃からメディアで頻繁に使用されるようになり、流行語化。
気象情報では「今日も猛暑日です」といった表現が定着。
熱中症対策の重要性が認識されるきっかけにもなった。

猛暑日は「現代の夏」の象徴

1️⃣ 昔はなかった「猛暑日」という言葉が必要になるほど、日本の夏は暑くなった。
2️⃣ 温暖化の影響で、今後も猛暑日は増えていく可能性が高い。
3️⃣ 「猛暑日」が当たり前になりつつある今、熱中症対策や環境問題への意識が重要。

A “heat wave day” is a meteorological term that refers to a day with a maximum temperature of 35°C (95°F) or higher.
The term was officially defined by the Japan Meteorological Agency in 2007; prior to that, no distinction was made.

Background of the term “extremely hot day
Extreme heat has increased due to global warming.
In the late 1990s, the number of summer days with maximum temperatures exceeding 35°C (86°F) began to increase.
The term “midsummer day (over 30°C)” was no longer sufficient to describe the intensity of the heat.

Abnormal weather in 2004 was the trigger.
In the summer of 2004, a record-breaking heat wave continued throughout Japan.
Tokyo also recorded a record high of 39.5°C (the highest temperature ever recorded), making it necessary to use a term to describe the “abnormal heat.
Later, in 2007, the Japan Meteorological Agency officially defined a “heat wave day.

Extremely hot day” and other heat standards
Term Maximum temperature
Extreme heat day 35°C or higher
Midsummer day 30°C or higher
Summer day 25°C or higher
Tropical night Minimum nighttime temperature 25°C or higher

Increase in the number of extremely hot days and global warming
The number of heat wave days is increasing.
Until the 1980s, heat wave days were rare.
Since the 2000s, heat wave days have been observed every year in many parts of the country.
Especially, the number of extremely hot days in urban areas has increased due to the heat island effect.

Impact of heat wave
Impact Description
Increase in heat stroke cases, especially among the elderly and children
Damage to crops Poor growth and quality of crops due to high temperatures
Increased electricity consumption Increased use of air conditioners, resulting in a sharp increase in electricity demand
Spread of the term “heat wave day
Around 2007, the term was frequently used in the media and became a buzzword.
Expression such as “It’s another extremely hot day today” became a common expression in weather reports.
It also served as a catalyst for the recognition of the importance of heat stroke countermeasures.

The extremely hot day is a symbol of “modern summer
1️⃣ Japanese summers have become so hot that the term “extremely hot day,” which did not exist in the past, has become necessary.
2️⃣ Due to global warming, the number of extremely hot days is likely to increase in the future.
3️⃣ Now that “extremely hot days” are becoming the norm, awareness of heat stroke prevention and environmental issues is important.

AIが描いた「猛暑日」