UV Index in Princeton, United States

Last updated: May 3, 2025

Understanding the UV Index is crucial for residents and visitors of Princeton, United States, especially given the region's climate characterized by hot summers and cold winters (Dfa climate zone). High UV levels can lead to sunburn and serious skin health issues, making awareness essential for outdoor activities. Typically, Princeton experiences significant UV exposure during the midday hours, peaking at 10 around 1 PM. By knowing the UV index, you can take proactive measures to protect your skin and enjoy the sun safely.

Hourly UV Index in Princeton

The UV Index throughout the day presents a dynamic picture of solar intensity. Morning hours start gently, with a low of 1 at 07:00 and a gradual rise to 2 by 08:00. As the sun climbs higher, the index peaks at a striking 10 at 13:00, signaling the most intense sun exposure, making it prudent for sun protection. From 14:00, the UV Index begins to dip, yet remains significant at 9, before tapering off to 5 by 16:00. As evening approaches, the levels drop further, resting at 1 by 19:00. This hourly progression showcases the importance of sun safety measures, particularly during those midday hours when the UV radiation is at its 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.
Time	UVI	Category	Time to Burn
07:00	1	low	45 min
08:00	2	low	45 min
09:00	3	moderate	30 min
10:00	5	moderate	30 min
11:00	7	high	25 min
12:00	9	very high	15 min
13:00	10	very high	15 min
14:00	9	very high	15 min
15:00	8	very high	15 min
16:00	5	moderate	30 min
17:00	3	moderate	30 min
18:00	2	low	45 min
19:00	1	low	45 min

Monthly UV Index Trends in Princeton

Throughout the year, the UV Index exhibits notable seasonal changes, with high-risk months typically occurring from April to August. In these months, the UV Index reaches its peak at 11, indicating an extreme exposure category, particularly in June and July where burn time is reduced to just 10 minutes. Visitors and residents should take extra precautions during this period, including wearing protective clothing, applying broad-spectrum sunscreen, and seeking shade, especially from midday to early afternoon when UV radiation is strongest. As summer transitions into fall, the UV Index gradually decreases, with moderate levels seen from November to March, allowing for safer outdoor activities during these months. Being aware of these variations can help individuals enjoy the outdoors while minimizing the risk of UV-related health effects.

Monthly Maximum UV Index for Princeton, United States

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

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

Princeton's solar exposure compared to other cities in United States. Generated using Copernicus Atmosphere Monitoring Service information.
	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Chicago UVI	3	4	6	8	9	10	10	9	8	6	4	2
Brooklyn UVI	3	5	6	8	10	10	9	9	8	6	4	2
New York City UVI	3	5	6	8	10	10	9	9	8	6	4	2
Princeton	3	5	6	9	10	11	11	9	8	6	4	3
Los Angeles UVI	4	6	8	9	10	11	11	10	10	7	5	4
Houston UVI	5	8	9	11	11	12	12	11	10	9	7	5