UV Index in Koshi, Japan

Last updated: June 2, 2025

In Koshi, Japan, being aware of the UV Index is crucial for protecting your skin and ensuring sun safety. With the region's Cfa climate, residents and visitors alike face varying levels of UV radiation that can lead to sunburn and long-term skin damage if not properly managed. Understanding these UV levels, especially during peak times where the index can soar to 11, is vital for enjoying the sunny days without compromising skin health. Stay informed and take the necessary precautions to safeguard yourself against the sun's impactful rays.

Hourly UV Index in Koshi

The UV Index reveals a dynamic sunlight profile throughout the day, peaking sharply at 11:00 AM, where it reaches a striking 11. As the sun rises, UV levels gradually climb from 2 at 7:00 AM to 3 by 8:00 AM, then making a significant leap to 6 by 9:00 AM. The intensity continues to escalate, hitting 8 by 10:00 AM, and remains relentlessly high at 11 from 11:00 AM to 1:00 PM. Following this peak, the UV Index begins to decline, dropping to 9 at 2:00 PM and subsequently to 7 at 3:00 PM. As the day winds down, UV exposure becomes milder, with values of 4, 2, 1, and ultimately settling at 1 by 7:00 PM. This data underscores the critical hours for sun safety, emphasizing the need for protective measures during the peak UV times.

Average solar exposure data for the current time of the year. Actual values may vary and depend on many factors, such as cloud cover, vegetation cover, surface type, etc.
Time	UVI	Category	Time to Burn
07:00	2	low	45 min
08:00	3	moderate	30 min
09:00	6	high	25 min
10:00	8	very high	15 min
11:00	11	extreme	10 min
12:00	11	extreme	10 min
13:00	11	extreme	10 min
14:00	9	very high	15 min
15:00	7	high	25 min
16:00	4	moderate	30 min
17:00	2	low	45 min
18:00	1	low	45 min
19:00	1	low	45 min

Monthly UV Index Trends in Koshi

Throughout the year, the UV Index exhibits significant seasonal variations, with spring and summer months posing the highest risk of UV exposure. From March to September, the index reaches very high to extreme levels—particularly during April to August, where it peaks at 12 in July and August. During these months, the burn time shortens dramatically to just 10 minutes, indicating a critical need for sun protection. Conversely, January and December record the lowest UV levels with a moderate exposure category, allowing for more extended exposure times of 30 minutes. Visitors and residents are advised to take precautions, especially from March to September, by wearing protective clothing, applying sunscreen, and seeking shade during peak hours to minimize the risks associated with high UV exposure.

Monthly Maximum UV Index for Koshi, Japan

The monthly maximum UV Index (UVI) represents the highest UV radiation level recorded each month in Koshi. It measures the strength of ultraviolet radiation from the sun and helps assess the risk of sunburn and UV-related health issues.

Data source: Statistical UV Index data for Koshi, based on information from the Copernicus Climate Change Service.

UV Risk Categories

Extreme (11+): Avoid the sun, stay in shade.
Very High (8-10): Limit sun exposure.
High (6-7): Use SPF 30+ and protective clothing.
Moderate (3-5): Midday shade recommended.
Low (0-2): No protection needed.

Compare Koshi UV Index with Other Japan Cities

The table above highlights how UV exposure in Koshi compares to other major locations across Japan. This comparison helps travelers and residents better understand regional sun intensity and plan outdoor activities with sun safety in mind.

Koshi's solar exposure compared to other cities in Japan. Generated using Copernicus Atmosphere Monitoring Service information.
	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Sapporo UVI	2	3	6	7	9	9	9	10	8	5	3	2
Yokohama UVI	3	5	8	9	11	11	11	11	10	7	5	4
Tokyo UVI	3	5	8	9	11	11	11	11	10	7	5	4
Nagoya UVI	4	6	8	10	11	11	11	11	10	7	5	3
Osaka UVI	4	6	8	11	11	11	12	11	10	7	5	3
Koshi	4	6	8	11	11	11	12	12	11	8	6	4