Japan’s 2025 Weather Review — Business Impacts of a Cold Winter and Record-Breaking Heat

2026.02.06

Japan’s weather in 2025 was marked by severe winter cold and record-breaking summer heat.

This article reviews Japan’s weather conditions in 2025, examines their impacts on businesses, and outlines weather risk countermeasures to consider from 2026 onward.

＊Japan’s 2026 Weather Outlook: Prepare for Extreme Heat, Heavy Rain, and Typhoons — Long-Term Forecast by JWA.

Table of Contents

What Kind of Weather Did Japan Experience in 2025? — Overview

Japan’s weather in 2025 can be summarized as “a year with sharp seasonal contrasts driven by a cold winter and extreme summer heat.”

• Winter: Severe cold across Japan
• Spring: Large temperature fluctuations and a tendency toward heavy rainfall
• Summer: A short rainy season followed by prolonged, record-breaking heat
• Autumn: Lingering summer heat in the first half, followed by a sudden cooling in the latter half

As a result, these rapid and extreme seasonal shifts may have made long-term business planning more challenging.

Looking Back at Japan’s 2025 Weather by Season

Winter 2024/2025: Winter-type pressure patterns tended to persist, leading to a nationwide cold winter trend

During the winter of 2024/25, repeated surges of strong cold air moved southward, resulting in severe cold conditions across Japan. Compared with the previous winter (2023/24), which was relatively mild, demand for winter-related products recovered.

Spring 2025: Large temperature fluctuations and a tendency toward heavy rainfall

Spring temperatures fluctuated widely, and compared with the previous season, which experienced notably high temperatures, the rollout of summer-related products was slower.

Although the peak pollen season occurred later than in the previous year (2024), pollen levels in western Japan were higher than the year before, supporting steady demand for allergy-related products.

Summer 2025: Short rainy season and record-breaking heat with prolonged extreme temperatures

In 2025, the rainy season was short and brought little rainfall, and intense heat set in starting in June.

The simultaneous strengthening and expansion of the Tibetan High and Pacific High pressure systems near Japan led to pronounced extreme heat.

Demand for cooling products and air-conditioning equipment increased significantly. At the same time, demand for products such as sports drinks did not grow as much as the previous year, due to reduced outings and the cancellation of outdoor sports caused by the heat.

Fall 2025: From lingering summer heat to a deepening fall in the latter half

Early autumn continued to experience intense lingering summer heat, but in the latter half, cold air moved southward, bringing temperatures more typical of late autumn.

Although the rollout of winter-related products remained slow, as in 2024, the late-autumn cooling boosted demand for cold-weather apparel, seasonal foods, and similar items, surpassing the previous year.

Why Was 2025 Marked by a Cold Winter and Extreme Heat?

Although a La Niña event did not occur in the tropical Pacific in 2025, sea surface temperatures remained similar to those typically observed during a La Niña, leading to severe cold in winter and record-breaking summer heat.

A La Niña event refers to a phenomenon in which sea surface temperatures are lower than average across the equatorial Pacific, from near the International Date Line to the coast of South America, and this condition persists for about a year.
When La Niña occurs, Japan tends to experience hot summers and cold winters.

＊Related article (tenki.jp): What Is La Niña? (Only Available in Japanese)

Weather Risk Countermeasures for 2026

As forecast by Japan Weather Association at the end of 2024, Japan’s 2025 weather followed a “high-contrast” pattern, with a cold winter and an extremely hot summer.

*Reference: 2025 Weather Trends – A Cold Winter, Early Spring, and an Extremely Hot Summer (released on December 20, 2024) (Only Available in Japanese)

This demonstrates that long-term weather forecasts, which capture overall annual trends, are highly valuable for business planning.

However, simply understanding long-term trends is not sufficient to achieve operational efficiency, reduce labor, or minimize losses.

By using long-term forecasts to identify broad annual trends, businesses can develop more informed plans for procurement, production, and marketing. Short-term forecasts can then be leveraged to fine-tune these plans based on predicted temperature changes, rainfall, typhoons, and snowfall, helping to enhance efficiency and reduce losses through weather-informed planning.

Compared with production planning based solely on previous-year results, weather-based planning can reduce weather-related waste and missed opportunities by 30–40%.

For the 2024 accuracy verification results of JWA Blend of Models, click here: 2024 Japan Weather Association’s Forecast Accuracy Verification Results
For more information on the weather complexities in other seasons, please visit: Why Is Japan’s Weather So Difficult to Forecast?

Reducing Business Losses by Leveraging Long-Term and Short-Term Forecasts

Japan Weather Association provides a wide range of meteorological data, from short-term forecasts covering the next few hours to outlooks up to two years ahead, along with consultation based on expert knowledge.

It is also possible to analyze past weather data to examine the relationship between products, services, and weather conditions.
Please feel free to contact us for more information.

Japan Weather Association’s Meteorological Data Services

Weather Data API

JWA’s weather API is designed to allow developers to access highly accurate weather information for any location. Data such as temperature, humidity, precipitation, snowfall, wind direction and speed, and general weather conditions can be retrieved in a single request through a user-friendly API.

For the overview, please see: Weather API Overview

2-Year Long-Term Weather Forecast (Only Available in Japanese)

JWA has developed the industry’s first forecasting method that offers higher accuracy and longer forecast periods than the conventional approach. This service provides numerical forecasts, including monthly temperature, amounts of precipitation/snowfall, sunshine duration, the start and end of the rainy season and typhoon activity.
In addition to data provision, we also offer consulting services to help clients make effective use of long-term forecasts.

In the 2-Year Long-Term Weather Forecast (Only Available in Japanese), we provide not only seasonal and monthly weather trends but also two-year-ahead demand forecasts for specific products, along with proposals for inventory and sales promotion timing. We also provide forecasting and consulting services on weather trends leading into 2026.

For details on 2-Year Long-Term Weather Forecasts, please click： What are Long-Term Forecasts? JWA’s Proprietary “2-Year Long-Term Weather Forecast” and Its Business Applications Part 1 / Part 2

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Professional Profile

Kumi Okoshi

The weather analysis and discussion of business impacts presented in this article have been supervised by Kumi Okoshi, Senior Data Analyst at Japan Weather Association.

In her role within JWA’s product demand forecasting business, she conducts market-oriented analyses and demand forecasts for industries such as food, daily necessities, and apparel, and provides consulting services to help companies address a wide range of business challenges.