Last updated: June 2, 2025
Understanding the UV Index is crucial for residents of Harriston, United States, as it plays a significant role in safeguarding against the harmful effects of ultraviolet radiation. Awareness of UV levels can help prevent sunburn and maintain long-term skin health, making it an essential aspect of outdoor plans, especially during the peak hours of exposure. With Harriston's Cfa climate, characterized by warm summers, the UV Index can reach high levels, peaking at 10 around noon and early afternoon. This guide will help you navigate these UV levels effectively, ensuring you enjoy the outdoors safely.
At dawn, 7:00 AM, the UV Index is a mild 1, offering a gentle start to the day. As the sun climbs higher, it steadily rises, reaching 2 by 8:00 AM and hitting 3 at 9:00 AM. However, between 10:00 AM and 1:00 PM, the intensity increases sharply, peaking at an impressive 10 from 12:00 PM to 1:00 PM—the highest level of risk. The UV Index then begins its descent, dropping to 8 at 3:00 PM, followed by a gradual decline to 4 by 5:00 PM. As evening approaches, the index wanes further, settling back down to 1 by 7:00 PM. To enjoy the sunshine while staying safe, make sure to take precautions, especially during those peak hours!
| 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 | 8 | very high | 15 min |
| 12:00 | 10 | very high | 15 min |
| 13:00 | 10 | very high | 15 min |
| 14:00 | 10 | very high | 15 min |
| 15:00 | 8 | very high | 15 min |
| 16:00 | 6 | high | 25 min |
| 17:00 | 4 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, UV index levels experience significant fluctuations, with high-risk months typically occurring from March to September. During this period, especially in April (UV Index 9), May (UV Index 11), and the peak summer months of June, July, and August (all at UV Index 10), the risk of harm from unprotected sun exposure is very high to extreme. The burn time decreases sharply, from 15 minutes in May to just 10 minutes, highlighting the urgent need for precautions. As such, visitors and residents are advised to wear protective clothing, apply broad-spectrum sunscreen regularly, and seek shade during peak sun hours to minimize the risks associated with high UV exposure. On the flip side, the winter months of January and December exhibit a moderate UV index (3), allowing for safer outdoor activities with a burn time of 30 minutes. Staying informed and taking appropriate measures can significantly reduce the risk of sun-related health issues across all seasons.
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 |
| Harriston | 3 | 5 | 7 | 9 | 11 | 10 | 10 | 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 |