Part 2. What are Long-Term Forecasts? JWA’s Proprietary “2-Year Long-Term Weather Forecast” and Its Business Applications

2025.07.07

Weather-related risks are increasing globally.
In Japan, the highly volatile weather patterns shaped by the country’s unique topography make the use of accurate weather forecasts essential for successfully conducting businesses. In particular, long-term forecasts play a vital role in business planning and strategic decision-making.

This article introduces the business application examples of how the Japan Weather Association’s (JWA) proprietary “2-Year Long-Term Weather Forecast”, is being applied in businesses, based on the overview provided in the previous article.
Part 1. What are Long-Term Forecasts? JWA’s Proprietary “2-Year Long-Term Weather Forecast” and Its Business Applications

Key Points of This Article

• JWA was the first in the weather industry to develop a proprietary extended long-term weather forecast: the 2-year long-term weather forecast.
• In practice, this forecast has already been applied in electric power and apparel industries, with strong potential for use across many other industries.
• By leveraging weather data to predict the future conditions, businesses can reduce losses and improve operational efficiency.

1. JWA’s Extended Long-Term Forecast: “2-Year Long-Term Weather Forecast”

With guidance and collaboration from Professor Hiroaki Ueda of the University of Tsukuba, JWA has developed the first “2-Year Long-Term Weather Forecast” technology in Japan’s weather industry. This forecast features three key characteristics:

• Higher accuracy and longer lead times compared to conventional long-term forecasts, enabling forecasts up to two years in advance.
• Quantitative forecasting that includes not only temperature but also other weather elements.
• Comprehensive services that go beyond data delivery including qualitative seasonal insights, along with customized consulting.

For more details about long-term forecasts and JWA’s “2-Year Long-Term Weather Forecast,” click here: Part 1. What are Long-Term Forecasts? JWA’s Proprietary “2-Year Long-Term Weather Forecast” and Its Business Applications

2. Business Applications: How Extended Long-Term Forecasts Support Strategic Decision-Making

Unlike general probabilistic forecasts, the “2-Year Long-Term Weather Forecast” provides quantitative forecasts up to two years ahead, offering the following strategic advantages for businesses:

• Improved planning accuracy
  Unlike the ratio to the climatological normal, probabilistic forecasts, or mean values typically used in long-term planning, this forecast provides concrete numerical forecasts up to two years in advance, enabling more precise business planning, simulations, and scenario development.
• Seamless integration with existing models
  Since the forecasts are provided in numerical format, they can be easily incorporated into existing automated forecast models and simulations, contributing to greater model refinement and improved forecasting accuracy.

Use Cases

Here’s how JWA’s “2-Year Long-Term Weather Forecast” is being applied in businesses.

【Electric Power Industry】

In the electric power sector, including both power generation and electricity retail businesses, the 2-Year Long-Term Weather Forecast can be utilized as an input to existing models for long-term electricity demand forecasting and power procurement planning.
By replacing traditionally used input values such as historical temperature records with scientifically predicted future weather data, more accurate forecasts with reduced margins of error can be achieved.

“2-Year Long-Term Weather Forecast” enables enhanced supply-demand forecasting, helping to reduce the risk of imbalances while optimizing the power generation mix. As a result, it supports efficient power procurement and stable supply-demand operations.

– Comparison: Monthly Average Temperatures in Eastern Japan (Pacific Side), May–September 2024

A verification study was conducted to evaluate how much the forecast error could be reduced—or forecast accuracy improved—by using JWA’s 2-Year Long-Term Weather Forecast instead of the “10-year historical average temperature,” which is typically applied in power supply-demand outlooks for the following year. The analysis focused on the monthly average temperatures in eastern Japan (Pacific side) between May and September 2024.
The results showed a significant improvement: Based on forecast data available 12 months in advance, the 2-Year Long-Term Weather Forecast demonstrated a 26.5% lower forecast error—or equivalently, a 26.5% improvement in accuracy—compared to the 10-year historical average temperature.

【Apparel Industry】

The issue of “fashion loss”, the large-scale disposal clothing despite still being wearable, whether new or used, has become a major social and environmental concern.

Because apparel products have a long lead time from planning to sales, demand forecasts more than 10 months in advance are necessary to appropriately control production volumes.

– Verification Study: Simulation on Reducing Clothing Waste

With data provided by Adastria Co., Ltd., which has set “create a world without fashion loss” as one of its sustainability goals, JWA conducted a simulation to assess how the 2-Year Long-Term Weather Forecast could help reduce fashion waste.
Using long-term temperature forecasts from 10 months before the ordering period timing, we projected the total seasonal sales of winter outerwear at stores in Tokyo. The results showed that, compared to production planning based on the previous year’s values, the forecast error was reduced by 14%.

Case cooperation: Adastria Co., Ltd.

【Other Industries】

Accurate long-term planning is important in any business.
In addition to the examples above, the 2-Year Long-Term Weather Forecast has potential applications in a wide range of industries:

• Logistics, Retail, Manufacturing
  • Inventory and store operation optimization based on seasonal consumption forecasts
  • Applications in the supply chain, such as adjusting transportation routes and logistics planning
  • Product demand forecasting
  • Product development
  • Annual marketing planning
• Finance, Insurance, Consulting
  • Weather risk assessment
  • Long-term investment and portfolio design
• Pharmaceuticals and Healthcare
  • Forecasting demand for vaccines and pharmaceuticals by anticipating the spread of infectious diseases and allergic conditions influenced by changes in temperature and humidity
• Energy
  • Optimization of power generation plans
  • Balancing long-term energy supply and demand
• Construction and Infrastructure
  • Optimization of construction processes and material procurement (based on temperature and precipitation forecasts)
  • Advance assessment of flood and drought risks and water resource management
• Agriculture
  • Enhancing crop selection and sowing plans based on region-specific temperature and precipitation forecasts
  • Yield forecasting for supply-demand adjustment and contract risk management
• Other Sectors
  • Industries that rely on annual planning such as tourism.

3. Conclusion: More Accurate Long-Term Forecasts Enhances Business Value

For companies conducting business in the Japanese market, where weather conditions are extremely volatile, the JWA’s “2-Year Long-Term Weather Forecast” empowers companies to transform weather from a “risk” into an “opportunity.”
By leveraging this forecast, businesses can improve the accuracy of future projections, reduce operational costs, and strengthen risk preparedness.

Having an outlook up to two years ahead enhances a company’s planning capacity, competitiveness, and sustainability.
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