UV Index in Hachioji, Japan

Last updated: May 3, 2025

Understanding the UV Index in Hachioji, Japan is essential for protecting your skin and overall health from harmful sun exposure. With UV levels peaking at 11 during midday, awareness of these fluctuations can help prevent sunburn and long-term skin damage. Given Hachioji's Cfa climate, characterized by warm summers, residents should be particularly vigilant about potential UV risks, especially during peak hours from 10 AM to 2 PM. By staying informed about the UV Index, you can take proactive measures to enjoy the sun safely, ensuring your outdoor activities are both fun and skin-friendly.

Hourly UV Index in Hachioji

The UV Index throughout the day shows a stark rise as the sun climbs higher in the sky. Starting at a modest 2 at 07:00, it quickly escalates, hitting 5 by 08:00. The peak occurs between 11:00 and 12:00, reaching a significant 11, indicating a high risk for damage from unprotected sun exposure. As the afternoon progresses, the index gradually decreases, dropping to 9 at 13:00 and further to 7 by 14:00. By late afternoon, the UV levels decline sharply, returning to 5 at 15:00, followed by a mere 2 at 16:00. As the sun sets, the UV Index falls to 1 at both 17:00 and 18:00, and finally reaches 0 by 19:00, signaling a safe end to sun exposure for the day. Be cautious during the midday hours when the sun's rays are strongest!

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	5	moderate	30 min
09:00	7	high	25 min
10:00	9	very high	15 min
11:00	11	extreme	10 min
12:00	11	extreme	10 min
13:00	9	very high	15 min
14:00	7	high	25 min
15:00	5	moderate	30 min
16:00	2	low	45 min
17:00	1	low	45 min
18:00	1	low	45 min
19:00	0	low	45 min

Monthly UV Index Trends in Hachioji

Throughout the year, seasonal changes in UV Index reveal significant variations in sun exposure risk. The high-risk months for UV exposure are predominantly from March to August, with the peak occurring in May, June, July, and August, where the UV Index reaches 11, categorized as extreme with a burn time of just 10 minutes. During this period, individuals are strongly advised to take precautions such as wearing sunscreen, protective clothing, and seeking shade, especially between 10 AM and 4 PM, when UV radiation is at its strongest. In contrast, the UV Index indicates moderate levels in January, November, and December, and high levels in October and February—months where sun safety should still be observed, though the urgency is somewhat reduced.

Monthly Maximum UV Index for Hachioji, Japan

The monthly maximum UV Index (UVI) represents the highest UV radiation level recorded each month in Hachioji. 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 Hachioji, 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 Hachioji UV Index with Other Japan Cities

The table above highlights how UV exposure in Hachioji 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.

Hachioji'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
Hachioji	4	6	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