Summer Solstice Sparks UV Spike: Heat Warnings Rise and Sunscreen Becomes a Must-Have Shield
The first day of summer arrives with intense sunshine and a spike in ultraviolet radiation. As heat warnings stretch across multiple states, understanding the UV Index is more crucial than ever.
- More information: Twinkling Fireflies Are Fading From Summer Nights
Today may feel longer than usual—and it is. With the summer solstice officially here, daylight stretches its limits while UV rays reach their peak. It’s a beautiful start to summer, but also a risky one if you’re not prepared.
UV Index and Solstice: A Perfect (and Dangerous) Storm
The summer solstice, arriving on June 20 at 10:42 p.m. EDT, marks the astronomical start of summer and the longest day of the year in the Northern Hemisphere. On this day, the Sun appears at its highest point in the sky, leading to increased solar radiation and higher UV exposure. According to the Environmental Protection Agency (EPA), this sunlight can feel especially harsh—and harmful—as the angle of sunlight is more direct than at any other time of year.
Summer Solstice the start of the astronomical summer is tonight at 10:42pm EDT. Though the hottest parts of summer are weeks away, this years solstice will usher in dangerously hot conditions in the Plains and Midwest this weekend, which will work to the East Coast by pic.twitter.com/KZUopNMDxc
— National Weather Service (@NWS) June 20, 2025
To help people gauge their risk, the National Weather Service (NWS) and EPA provide a daily UV Index, which forecasts the intensity of UV radiation on a scale from 1 to 11+. While low levels (1–2) pose minimal risk, readings of 6 or higher require protective action. On summer solstice days, especially with clear skies and high temperatures, UV levels often exceed 8 in many parts of the country.
Extreme Heat Warnings Compound the Risk
As if intense UV rays weren’t enough, much of the central U.S. is under Extreme Heat Warnings today.
These dangerously high temperatures not only increase the risk of dehydration and heat stroke but also heighten UV radiation exposure—especially for outdoor workers, children, and the elderly.
The next several days will feature not only high daytime temperatures, but also very warm nights not allowing our bodies to recover if precautions arent taken. Everyone is at risk from the dangers of extreme heat, but these groups are more vulnerable than most. Ensure that pic.twitter.com/ZtHbQDIW4k
— National Weather Service (@NWS) June 20, 2025
Health officials advise limiting outdoor activity between 10 a.m. and 4 p.m., when UV radiation is strongest. Loose, light-colored clothing, wide-brimmed hats, and frequent hydration are essential. In many areas, the high humidity and lack of overnight cooling make recovery difficult, particularly for vulnerable populations.
How to Use Sunscreen Effectively
Shielding your skin from UV damage takes more than a quick grab from the sunscreen aisle. Sunscreens are classified into two main types: mineral (physical) and chemical. Mineral sunscreens use ingredients like zinc oxide to reflect UV rays, while chemical sunscreens absorb UV radiation and convert it into heat. Look for sunscreens labeled “broad-spectrum,” which means they protect against both UVA (aging) and UVB (burning) rays.
The American Academy of Dermatology recommends using at least SPF 30, applying generously 15 minutes before sun exposure, and reapplying every two hours—or immediately after swimming or sweating. The EPA notes that reflective surfaces like sand, water, and pavement can significantly increase UV exposure.