Steam-Bath Heat (Jjimtongdeowi)

Steam-bath heat (찜통더위) is a phenomenon where the perceived temperature becomes extremely high due to hot and humid weather, seriously affecting health and society.

Steam-Bath Heat (찜통더위)

Overview

Steam-bath heat (찜통더위) refers to hot and humid weather where summer temperatures rise above 33°C and humidity exceeds 80%, creating a stifling heat akin to being inside a steamer. This phenomenon often occurs alongside tropical nights (열대야), rapidly increasing the perceived temperature and potentially causing heat-related illnesses such as heatstroke and heat exhaustion. Due to recent climate change, the frequency and intensity of steam-bath heat are increasing, making preparation and response crucial.

Main Content

Definition and Characteristics

Steam-bath heat is not merely about high temperatures; it also involves high humidity that prevents sweat evaporation, making body temperature regulation difficult. Meteorologically, it is commonly used when the daily maximum temperature is 33°C or higher and relative humidity is 70% or more, with the perceived temperature potentially feeling 5–10°C higher than the actual temperature. Under these conditions, the body's heat dissipation is impaired, leading to a sharp increase in heat stress.

Causes

The main causes of steam-bath heat are as follows:

Expansion of the North Pacific High: When the North Pacific High, which affects the Korean Peninsula in summer, strengthens, hot and humid air flows in.
Association with Tropical Nights: If tropical nights, where nighttime temperatures do not fall below 25°C, persist, the heat accumulated during the day is not released, intensifying steam-bath heat.
Urban Heat Island Effect: Urban areas covered with asphalt and concrete absorb and release heat, raising temperatures higher than surrounding areas.
Climate Change: Global warming raises the global average temperature, leading to more frequent extreme high-temperature events.

Health Effects

Steam-bath heat has various negative effects on the human body:

Heat-Related Illnesses: Heatstroke, heat exhaustion, heat cramps, and heat syncope can occur, with the elderly and those with chronic diseases at higher risk.
Cardiovascular Strain: High temperatures dilate blood vessels and increase heart rate, putting strain on the cardiovascular system.
Worsening of Respiratory Diseases: High humidity can exacerbate symptoms in patients with asthma or chronic obstructive pulmonary disease (COPD).
Mental Health: Persistent heat can affect mental health, causing insomnia, irritability, and depression.

Socioeconomic Impacts

Steam-bath heat has widespread effects across society:

Surge in Electricity Demand: Cooling demand skyrockets, straining the power grid and increasing the risk of blackouts.
Agricultural Damage: Drought and high temperatures can hinder crop growth and cause livestock deaths.
Transportation Disruptions: Rail tracks may deform, road asphalt can melt, and aircraft takeoffs and landings may be delayed.
Reduced Productivity: Outdoor workers' efficiency declines, and indoor workers also face difficulties due to increased cooling costs.

Preparation and Response

Methods to prepare for steam-bath heat include:

Individual Level: Drink plenty of water, avoid going out, wear light clothing, and use cooling devices appropriately.
Government Level: Issue heat wave warnings, operate cooling shelters, and establish protection measures for vulnerable groups.
Urban Planning: Expand green spaces, implement rooftop greening, and use heat-reflective paints to mitigate the urban heat island effect.

Recent Trends

In 2024 and 2025, record-breaking heat waves have continued globally. 2024 was recorded as the first year the global average temperature exceeded 1.5°C above pre-industrial levels, with steam-bath heat particularly intensifying in East Asia. In South Korea, the number of tropical nights in Seoul broke the all-time record in the summer of 2024, and in 2025, an early heat wave began in June, with extreme steam-bath heat expected in July and August. The Korea Meteorological Administration predicts that the frequency of steam-bath heat will increase more than threefold compared to the 1990s due to climate change, leading to strengthened heat wave response manuals. Additionally, an artificial intelligence (AI)-based heat wave prediction system has been introduced, enabling more accurate early warnings, and projects to mitigate the heat island effect using smart city technologies are actively underway.