UV Index in Shiojiri, Japan

Last updated: June 2, 2025

Understanding the UV Index in Shiojiri, Japan, is crucial for maintaining optimal skin health and preventing sunburn, especially during those sun-soaked summer days. With the region’s Dfb climate, Shiojiri experiences substantial UV exposure, particularly between 10:00 AM and 1:00 PM, when UV levels peak at a blistering 11. Being aware of these UV levels empowers residents and visitors to take necessary precautions, such as wearing sunscreen and protective clothing, to enjoy the beautiful outdoors safely while preserving long-term skin health.

Hourly UV Index in Shiojiri

The UV Index throughout the day exhibits a clear peak around midday, reflecting the sun's intensity. Starting from a mild 2 at 07:00, it swiftly rises to a moderate 5 by 08:00. By 09:00, the index escalates to a more intense 7, reaching a notable 10 at 10:00, and hitting its maximum of 11 at both 11:00 and 12:00. As the afternoon progresses, the index begins to decline, dropping to 10 at 13:00, then gradually lowering to 8 at 14:00 and 6 by 15:00. The evening sees a rapid decrease, with values falling to 3 at 16:00, then to 2 at 17:00, and finally tapering off to 1 at 18:00 and 0 by 19:00. This pattern emphasizes the importance of sun protection during the peak hours of 11:00 to 14:00 when UV exposure is highest.

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.
TimeUVICategoryTime to Burn
07:002low45 min
08:005moderate30 min
09:007high25 min
10:0010very high15 min
11:0011extreme10 min
12:0011extreme10 min
13:0010very high15 min
14:008very high15 min
15:006high25 min
16:003moderate30 min
17:002low45 min
18:001low45 min
19:000low45 min

Monthly UV Index Trends in Shiojiri

Throughout the year, UV index levels fluctuate, with the most significant increases occurring from March to September. During these months, particularly in May, June, July, and August, the UV index reaches its peak at 12, categorized as extreme, with a burn time of just 10 minutes. March and April also present high risks, featuring very high UV levels of 9 and 10 respectively. Visitors and residents should be particularly vigilant in these high-risk months, applying sunscreen, wearing protective clothing, and seeking shade whenever possible. As UV levels decrease from late summer into fall and winter, with January and December categorized as having moderate exposure (UV index 4), precautions remain advisable to ensure skin protection year-round.

Monthly Maximum UV Index for Shiojiri, Japan

The monthly maximum UV Index (UVI) represents the highest UV radiation level recorded each month in Shiojiri. It measures the strength of ultraviolet radiation from the sun and helps assess the risk of sunburn and UV-related health issues.
JanFebMarAprMayJunJulAugSepOctNovDec469101111121210754
Data source: Statistical UV Index data for Shiojiri, 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 Shiojiri UV Index with Other Japan Cities

The table above highlights how UV exposure in Shiojiri 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.
Shiojiri's solar exposure compared to other cities in Japan. Generated using Copernicus Atmosphere Monitoring Service information.
 JanFebMarAprMayJunJulAugSepOctNovDec
Sapporo UVI2367999108532
Yokohama UVI35891111111110754
Tokyo UVI35891111111110754
Nagoya UVI468101111111110753
Osaka UVI468111111121110753
Shiojiri469101111121210754