Last updated: July 2, 2025
Understanding the UV Index is crucial for residents of Ashburn, United States, where the climate typically belongs to the humid subtropical zone (Cfa), resulting in significant sun exposure. Awareness of UV levels is vital for sunburn prevention and maintaining long-term skin health, especially during the peak hours when the index reaches a maximum of 11 around noon. With UV radiation intensity varying throughout the day, knowing when to seek shade or apply sunscreen can help protect you and your loved ones from harmful effects. Stay informed and arm yourself against the sun's rays to enjoy Ashburn's sunny days safely!
The UV Index throughout the day exhibits a remarkable peak, beginning at a low 1 in the early hours, gradually rising to 5 by 10:00. As the sun reaches its zenith, the index soars to an impressive 10 at 12:00, hitting a maximum of 11 from 13:00 to 14:00. This intense exposure makes midday the most critical time for sun protection. As the afternoon progresses, the index begins to dip, falling to 7 at 16:00, and winding down to a gentle 3 by 18:00. By 19:00, the UV Index drops back to 1, signaling a return to safer sun conditions. Planning outdoor activities? Make sure to take precautions from late morning to mid-afternoon, when the sun’s rays are most powerful!
| 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 | 10 | very high | 15 min |
| 13:00 | 11 | extreme | 10 min |
| 14:00 | 11 | extreme | 10 min |
| 15:00 | 10 | 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 the highest risk observed during the spring and summer months. From February to August, the UV Index remains at a very high to extreme level, peaking at 11 in May, June, July, and August, where the burn time is as short as 10 minutes. Visitors and residents are advised to take extra precautions during these months by wearing protective clothing, applying sunscreen regularly, and seeking shade, especially during midday hours. In contrast, January and December experience moderate UV levels, allowing for longer exposure times of 30 minutes before burning. As the UV levels decline entering the fall months, particularly in November with a high index of 6 (burn time of 25 minutes), it is still prudent to remain vigilant against UV exposure.
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 |
| Los Angeles UVI | 4 | 6 | 8 | 9 | 10 | 11 | 11 | 10 | 10 | 7 | 5 | 4 |
| Ashburn | 5 | 8 | 9 | 10 | 11 | 11 | 11 | 11 | 10 | 8 | 6 | 4 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |