Snow in Japan Explained

2025.12.23

Introduction: Why Is Japan One of the Snowiest Countries in the World?

Key Points

• Japan is one of the snowiest countries in the world.
• Heavy snowfall occurs due to the combination of “seasonal winds, sea conditions, and mountain ranges.”
• Snow has significant impacts on tourism, infrastructure and industry, making it an important weather factor for businesses.

Explanation

Across Japan, there are many regions that rank among the world’s heaviest snowfall areas. This is closely linked to Japan’s unique environmental conditions, the combination of Siberian cold air, sea surface temperatures of the Sea of Japan, and orographic effects caused by mountain ranges.

For an overview of weather APIs and services that can be used for winter risk management, please click: Japan’s 2025–2026 Winter Snow Risks: Business Impacts and Solutions for Logistics, Energy, and Retail

Table of Contents

The Mechanisms Behind Heavy Snowfall in Japan

Key Points

Heavy snowfall along the Sea of Japan coast can be explained by the combination of the following three factors:

• Strong northwesterly seasonal winds from the Siberian cold air mass
• Rapid development of snow clouds over the Sea of Japan
• Orographic snowfall caused by mountain ranges

Siberian Cold Air Mass: The “Engine” of Japan’s Winter

In winter, intense cooling over Siberia leads to the formation of a massive high-pressure system. Cold, dry seasonal winds flowing out from this high- pressure system form the foundation of Japan’s winter climate.

Why Snow Clouds Rapidly Develop Over the Sea of Japan

Snowfall along the Sea of Japan coast occurs when Siberian cold air absorbs water vapor while passing over the Sea of Japan. In particular, when the “JPCZ (Japan Sea Polar Air Mass Convergence Zone)” forms, snow clouds intensify rapidly, resulting in heavy snowfall.

Seasonal Winds Are Lifted by Mountains → Heavy Snowfall (Orographic Snowfall)

The mountains of the Japanese archipelago act as a “wall,” and when moist seasonal winds collide with them, the resulting upward airflow allows snow clouds to develop. As a result, strong snowfall occurring over a short period is frequently observed.
This mechanism is known as orographic snowfall.

Characteristics of Snowfall by Region

Key Points

• Snow characteristics vary significantly by region in terms of snowfall amount, snow quality, and timing.

Hokkaido: Light Snow Produced by Low Temperatures

Hokkaido remains under persistent cold air throughout winter and is globally known for its high-quality snow. In particular, ski resorts are highly regarded for their light powder snow known as “Japow.”

• Sub-zero temperatures often persist for long periods during winter.
• Because low temperatures prevent snow from melting easily, light powder snow tends to fall.
• Representative areas: Sapporo, Niseko

Tohoku (Sea of Japan Side): One of the World’s Heaviest Snowfall Regions Due to Topography

The Sea of Japan side of Tohoku is one of the world’s heaviest snowfall regions. Cold air flows in from Siberia, and under the influence of terrain such as the Ou Mountains, snow clouds readily develop, sometimes causing snow accumulation to increase rapidly in a short time.

• Cold air collides with the Ou Mountains, making orographic snowfall more likely to intensify.
• Both snowfall and snow depth rank among the highest nationwide.
• There are many deep-snow areas (such as Aomori and Akita Prefectures), where snow accumulation tends to continue increasing.

Hokuriku: One of the World’s Heaviest Snowfall Regions Where Wet Snow Accumulates in Layers

In Hokuriku, winter monsoon winds travel for long distances over the relatively warm Sea of Japan, absorbing large amounts of water vapor. When this air collides with mountainous terrain, snow clouds develop, forming a continuous belt of heavy snowfall regions despite the area’s relatively low latitude.

Compared with Hokkaido and Tohoku, temperatures are relatively higher and often hover around 0°C, resulting in snow with a high liquid water content that can accumulate rapidly within a short period.

• Strong moisture uptake from the Sea of Japan combined with near-freezing temperatures leads to wet, heavy snow.
• Continuous inflow of snow clouds can result in prolonged snowfall events.
• Snow tends to be wet and heavy, so increases in accumulation often result in greater-than-expected burdens, such as snow removal and snow accretion.

Pacific Coast Regions: Limited Snowfall but Still at Risk of Heavy Snow

While the Pacific side of Japan often experiences clear weather under a typical winter pressure pattern, snowfall can occur when this pattern weakens—such as toward the end of winter—and low-pressure systems pass along the southern coast of Honshu.

Even in regions where snowfall is usually limited, if temperatures and the track of the low-pressure system align, snow can accumulate within a short time, potentially causing widespread transportation disruptions.

• Winters are characterized by abundant sunshine and a dry climate, and snowfall is generally limited.
• Depending on the track of southern coastal low-pressure systems and temperatures, heavy snow can occur in regions such as Kanto and Tokai.
• In snow-unaccustomed areas, even a few centimeters of snow can significantly impact transportation and daily life.

Meteorological Conditions That Create “Japow”

Key Points

“Japow” is a coined term combining “Japan” and “powder snow” and is widely used among skiers worldwide. This high-quality powder snow is formed when Japan’s unique meteorological conditions come together.

• Low temperatures
• Dry air
• Stable, continuous inflow of cold air
• Snowfall pattern that does not damage snow crystals

Conditions for Powder Snow

Japan’s powder snow is produced when environmental conditions allow snowflakes to remain intact. In particular, temperature, humidity, and wind are key factors.

• Sub-zero freezing temperatures
  Because temperatures are low, snowflakes are less likely to melt and can reach the ground in a light state.
• Moderately low humidity
  Snowflakes are less likely to absorb excessive moisture, resulting in dry, fluffy snow.
• Effects of wind and terrain
  On the leeward side of mountains, snowflakes are less likely to break, allowing high-quality snow to fall consistently.

Why Hokkaido’s Snow Is Highly Valued Worldwide

Hokkaido is known as one of the world-famous regions for enjoying high-quality powder snow. This is due to its severe winter temperatures and meteorological conditions.

• Because severe cold persists throughout winter, snowflakes are less likely to melt and tend to remain light.
• Cold, dry air from the continent flows in steadily, allowing high-quality snow crystals to fall without breaking.
• The terrain and wind patterns bring gentle snowfall in which snowflakes are less likely to be damaged, creating an environment well suited for powder snow formation.

As these factors combine, there are many regions where so-called “light and deep snow” falls in a stable and consistent manner.

How Snow Quality on Honshu Differs from Hokkaido

On Honshu, differences in temperature and humidity conditions compared with Hokkaido lead to differences in snow quality.

• Honshu generally experiences higher temperatures and humidity than Hokkaido, so snowfall tends to be wetter.
• Along the Sea of Japan side of Honshu, air containing water vapor from the sea often coincides with temperatures around 0°C , making wet , heavy snow more likely to fall.

Business Risks and Impacts of Japan’s Snow Season

Key Points

Snow in Japan affects business operations in multiple ways.
Blizzards, icy roads, and transportation disruptions pose risks to logistics, supply chains, employee mobility, and demand fluctuations.
Effective winter business continuity requires understanding weather risks, making advance operational adjustments, and leveraging real-time weather data.

Blizzards and Whiteouts

• Reduced visibility can delay or halt logistics and employee travel across wide areas, affecting delivery planning and on-site operations.
• Outdoor work such as construction, inspections, and maintenance may be temporarily suspended for safety reasons, raising concerns about project delays.
• If vehicles become stranded on major highways, delays can cascade throughout the entire supply chain.

Road Surface Freezing (Black Ice)

• During commuting and delivery operations, the risk of slip-and-fall accidents and vehicle accidents increases, which may result in employees being unable to go to work and in operational delays.
• In commercial facilities, slip-and-fall accidents involving customers may occur, increasing the need for safety measures and compensation responses.
• Icy conditions around logistics hubs and factories may delay operations and reduce efficiency.

Heavy Snowfall

• Rapid snow accumulation can increase snow removal costs and disrupt store or facility operations.
• Employees may have difficulty commuting or traveling to their workplaces, making shift adjustments necessary and potentially affecting operations and business hours.
• In snow-unaccustomed regions such as the Pacific side, even a few centimeters of snow can cause major transportation disruptions and demand fluctuations.

Winter-Specific Demand Fluctuations

• Depending on heavy snow forecasts and snow accumulation conditions, demand for food and daily necessities in retail and e-commerce may increase.
• In the tourism, dining, and leisure sectors, reservation cancellations and decreases in visitor numbers may occur depending on the timing of snowfall.
• Energy demand rises during winter, increasing pressure on fuel supplies, heating equipment, and logistics, requiring proactive preparation.

Using Weather Data for Business

• 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

• Logistics-oriented GoStop Management System

  Provides transport impact risk information caused by weather conditions, supporting decisions that help protect lives and cargo in logistics operations.

• Product Demand Forecasting

  Analyze product sales and weather data to forecast product demand and customer traffic to adjust production volume and optimize inventory management.

• Electric power demand forecasting

• ENeAPI, a Comprehensive API Service for the Energy Industry

• 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, and sunshine duration.
  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 the spring and summer seasons of 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

Conclusion

Key Points

• Heavy snowfall along the Sea of Japan coast is a unique phenomenon created by Siberian cold air, Sea of Japan sea surface temperatures, and orographic effects.
• Snow characteristics vary by region.
• Japan has globally rare, high-quality powder snow.
• During the snow season, risk management using weather data is essential.

*For more details on the complexity of weather in other seasons, please click: Why Is Japan’s Weather So Difficult to Forecast?

*For the 2024 accuracy verification results of JWA Blend of Models,” please click: 2024 Japan Weather Association’s Forecast Accuracy Verification Results