Last updated: July 2, 2025
In London, United States, understanding the UV Index is crucial for maintaining skin health and preventing sunburn. The UV Index provides valuable information about the strength of ultraviolet radiation from the sun, helping residents make informed decisions about sun exposure. With a Cfa climate, characterized by warm summers, London experiences significant variation in UV levels throughout the day. For instance, UV levels peak at a hazardous 11 around midday, highlighting the importance of protective measures during outdoor activities. Being aware of these fluctuations empowers you to enjoy the sun safely while protecting your skin from potential damage.
The UV Index today presents a dynamic profile, beginning at a calm 1 by 07:00 and remaining low until it reaches 2 by 09:00. The real action starts around 10:00, where the index jumps to 5, setting the stage for peak sunlight. By 12:00, the index soars to a significant 9, creating a strong midday sun that only intensifies, peaking at an impressive 11 between 13:00 and 14:00. As the afternoon progresses, the intensity starts to wane, dipping to 9 at 15:00, then 7 by 16:00, and gradually easing to a gentle 3 as evening approaches. By 19:00, the index falls back to 1, indicating a safe time to enjoy the sunset. Remember to protect your skin during the highest UV exposure hours!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 1 | low | 45 min |
| 09:00 | 2 | low | 45 min |
| 10:00 | 5 | moderate | 30 min |
| 11:00 | 7 | high | 25 min |
| 12:00 | 9 | very high | 15 min |
| 13:00 | 11 | extreme | 10 min |
| 14:00 | 11 | extreme | 10 min |
| 15:00 | 9 | very high | 15 min |
| 16:00 | 7 | high | 25 min |
| 17:00 | 5 | moderate | 30 min |
| 18:00 | 3 | moderate | 30 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, UV Index levels fluctuate significantly, with higher risks typically observed from March to August. The high-risk months are especially highlighted in April, May, June, July, and August, where the UV Index reaches extreme levels of 11 and the recommended burn times drop to just 10 minutes. Visitors and residents are strongly advised to take protective measures during these months, such as wearing sunscreen, protective clothing, and seeking shade, particularly during midday hours. As the year progresses towards the fall and winter months, UV exposure decreases, making January and December months of moderate risk, where burn times are longer at 30 minutes. Staying informed about daily UV levels can help ensure safety while enjoying outdoor activities.
UV Risk Categories
| 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 |
| London | 3 | 6 | 7 | 9 | 11 | 11 | 11 | 10 | 9 | 7 | 5 | 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 |