Last updated: May 3, 2025
Understanding the UV Index is crucial for residents of Lancaster, United States, as it provides essential information about the intensity of ultraviolet (UV) radiation from the sun. Awareness of UV levels is key for preventing sunburn and maintaining skin health, particularly during the sunnier months when the UV Index peaks around midday. Lancaster’s climate, characterized by warm summers and cold winters, presents unique challenges, with afternoon UV levels often reaching as high as 9—a risk factor for overexposure. By staying informed about the UV Index, you can take proactive measures to protect your skin and enjoy the outdoors safely.
As the sun rises, the UV Index gradually climbs, starting at a mild 1 at 07:00. By 08:00, it nudges up to 2, signaling a gentle start to the day. The real intensity kicks in at 09:00, reaching 4, and peaks impressively at 12:00 with a high of 9. The UV levels remain strong throughout the afternoon, holding at 9 until 13:00, before tapering off slightly to 8 at 14:00. By 15:00, it decreases to 7, and as the sun begins its descent, the index drops dramatically, hitting 4 by 16:00 and further declining to a safe 1 by 18:00 and 19:00. Staying sun-safe during the peak hours between 10:00 and 14:00 is essential to protect your skin from harmful UV rays!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 2 | low | 45 min |
| 09:00 | 4 | moderate | 30 min |
| 10:00 | 6 | high | 25 min |
| 11:00 | 8 | very high | 15 min |
| 12:00 | 9 | very high | 15 min |
| 13:00 | 9 | very high | 15 min |
| 14:00 | 8 | very high | 15 min |
| 15:00 | 7 | high | 25 min |
| 16:00 | 4 | moderate | 30 min |
| 17:00 | 3 | moderate | 30 min |
| 18:00 | 1 | low | 45 min |
| 19:00 | 1 | low | 45 min |
The UV Index exhibits notable seasonal changes throughout the year, with high-risk months primarily occurring from April to August, when the index reaches very high levels (8-10) and a burn time of just 15 minutes is recommended. Specifically, April through July are critical periods, with May and June experiencing the highest values. During these months, it is essential for visitors and residents to take precautions such as wearing sunscreen, protective clothing, and sunglasses, and seeking shade during peak sun hours. Conversely, January and December present lower risks with a UV Index of 2-3, allowing for more extended sun exposure of up to 45 minutes and only moderate protection needed. Overall, staying informed of the UV Index can help ensure safety and enjoyment while outdoors year-round.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Lancaster | 3 | 5 | 6 | 8 | 9 | 10 | 9 | 9 | 7 | 6 | 4 | 2 |
| 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 |
| 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 |