- July 1, 2025
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- BELONGING JAPAN
The heat in Japan during summer can be intense—humid, relentless, and increasingly unpredictable. In 2025, forecasters are already warning of higher-than-average temperatures across the country, with the rainy season expected to end earlier than usual. Whether you’re visiting or living in Japan, preparing for this extreme heat is essential to stay safe and comfortable. This article covers what to expect from the heat in Japan in 2025 and introduces must-have items and tips to help you beat the heat effectively.
Table of Contents
Chapter 1: Heat in Japan 2025 – What to Expect
The heat in Japan is expected to be especially intense in 2025. According to the Japan Meteorological Agency’s forecast for July through September, strong high-pressure systems are likely to linger over the country, bringing warm air and pushing temperatures well above average nationwide.
Normally, Japan enters the rainy season—tsuyu—in June, with cooler, damp weather lasting until mid-July. During this time, it’s rare for temperatures to reach 30°C (86°F). But this year, the rainy season may end as early as late June, making way for full-on summer heat much earlier than usual.
As a result, the heat in Japan this summer is expected to start sooner, last longer, and feel more intense. With high humidity, limited shade in cities, and little overnight relief, the risk of heat-related illness will rise. It’s important to stay alert and take steps to stay cool and safe throughout the season.
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Chapter 2: Essential Items to Beat the Heat in Japan
To stay safe during the intense heat in Japan, the Japan Meteorological Association recommends preparing around four key areas of heatstroke prevention. These basics help you stay cool, avoid overheating, and protect your health during the peak summer months.
Source: Heatstroke Zero
1. Hydration and Salt intake
The first and most important point is hydration and salt intake. In Japan’s humid climate, it’s easy to lose both water and essential minerals through sweat. Simply drinking water isn’t always enough—you also need to replenish electrolytes. Carry a reusable water bottle and consider drinks with added salt or electrolytes, like sports drinks or oral rehydration solutions (経口補水液 or OS-1 sold in pharmacies and convenience stores). Salt tablets and supplements can also be helpful, especially during outdoor activities.
*Oral rehydration solutions (ORS) are not the same as regular sports drinks—they’re specifically designed to treat dehydration. If you’ve been advised by a doctor to limit your sodium or potassium intake, be sure to consult your physician before using them.
2. Stay Out of the Sun and Dress Smart
Light Blocking Parasol
One of the best ways to protect yourself from the intense heat in Japan is by avoiding direct sunlight—and a parasol is your best friend. While some people may feel strange using an umbrella on sunny days, parasols are a common and essential item in Japan during summer. In fact, with the sun getting stronger each year, more and more men are carrying them too.
When choosing a parasol, look for one with a 遮光率 (shakōritsu) of 99.9% or higher. This is the light-blocking rate, which indicates how much visible sunlight the fabric can block—not to be confused with the UV protection rate, which refers specifically to blocking ultraviolet rays. The higher the shakōritsu, the more effective the parasol is at keeping out intense sunlight and heat.
Shakōritsu is usually classified as:
Grade 1: Blocks 99.99% or more of visible light
Grade 2: Blocks 99.80% to less than 99.99%
Grade 3: Blocks 99.40% to less than 99.80%
For extra convenience, look for a parasol that’s suitable for both sun and rain. Sudden showers are common during the Japanese summer, so a dual-purpose umbrella will keep you protected in all conditions.
Neck Ring
A cooling neck ring is a great item to have during your commute, on your way to school, or even while walking your dog. Just chill it in the freezer and put it on before heading out. If you choose one that solidifies below 28°C (82°F), it will naturally refreeze in air-conditioned places like offices—so you can use it again on your way home.
If you prefer a towel-like fabric, there are also scarf-type cooling wraps that retain moisture and provide lasting relief. While they may not feel as instantly cold as frozen neck rings, they offer a comfortable, sustained coolness—especially when exposed to a breeze.
3. Stay Aware of Your Environment
It’s important to check the actual temperature—whether through TV, online news, or weather apps—before going outside or planning how to stay cool at home. Many people suffer from heatstroke indoors, often because they don’t feel particularly hot and skip using the air conditioner, only to realize too late that they were overheated.
To avoid this, especially when pets are home alone, a thermometer can be very helpful. A device that monitors both indoor and outdoor temperatures is especially useful for staying aware of changing conditions and taking timely precautions.
4. Keep Your Body Cool
Lastly, it’s important to have items that help cool your body directly. One practical option is an ice bag. While neck coolers are easy to wear, they don’t stay cold for long. Ice bags, on the other hand, can be filled with water and frozen or used with ice stored in an insulated bottle for on-the-go cooling.
When you’re ready to use it, take the ice bag out and place it on your neck or joints to quickly lower your body temperature. When you’re done, just pop it back into the insulated case to keep it cold. Since it doesn’t produce condensation, it’s safe to carry in your bag. Plus, in winter, you can fill it with warm water and use it as a hot pack—making it a handy item all year round.
If you commute with a backpack, you’ve probably noticed how hot it can get between your back and the bag, even with a parasol. In that case, a cooling pad designed for backpacks can be a great solution. Just chill it in the refrigerator or freezer and attach it to your backpack using the built-in hooks.
You can reuse it throughout the day by simply running it under cold water—perfect for refreshing it in the restroom at your office or school before heading home.
* When you purchase products introduced in the content, a portion of the sales may be returned to belongingJAPAN.
*Please note that there may be changes in availability or pricing. The prices listed above are as of June 10th, 2025. For further details, please check Amazon.co.jp.
