DermUV
Monthly UV Index
Charleston, SC
Monthly UV Index in Charleston, SC
Average UV in Charleston is highest during May, Jun, Jul and lowest during Jan, Dec. Use this month-by-month guide to plan sunscreen, shade, clothing, and outdoor timing.
Charleston UV Index by Month
Average UV in Charleston peaks during May, Jun, Jul, when high sun angles combine with longer days. The deceptive months are usually early spring and early fall, when air temperatures stay mild but UV climbs into the high category by mid-morning. Locals often skip sunscreen on cool, overcast days, which is exactly when UV-A continues to drive long-term skin damage. UV in Charleston is lowest during Jan, Dec.
| Month | Avg UV | Risk |
|---|---|---|
| Jan | 6.1 | High |
| Feb | 7.6 | High |
| Mar | 9.4 | Very High |
| Apr | 11.0 | Extreme |
| May | 11.8 | Extreme |
| Jun | 12.0 | Extreme |
| Jul | 11.9 | Extreme |
| Aug | 11.4 | Extreme |
| Sep | 10.1 | Very High |
| Oct | 8.3 | Very High |
| Nov | 6.5 | High |
| Dec | 5.7 | Moderate |
Highest UV Months in Charleston
Peak monthly UV reaches about 12.0 in May, Jun, Jul. That is the period when unprotected skin burns fastest, especially near solar noon. Check the live UV index in Charleston, SC before outdoor plans because clouds, ozone, altitude, and reflection can move the real-time number above or below the monthly average.
Lowest UV Months in Charleston
Monthly UV is lowest in Jan, Dec, around 5.7 on this model. Lower UV does not mean zero UV. UVA can still pass through cloud and glass, and snow, water, or pale concrete can reflect UV back onto exposed skin.
Monthly Sunscreen Guidance for Charleston
For months that average UV 3 or higher, broad-spectrum SPF 30+, sunglasses, shade, and UPF clothing are the practical baseline. For months in the very-high or extreme range, reapply every two hours outdoors and after swimming or heavy sweat. These are educational estimates.
Related Charleston UV Pages
Using UV Index Charleston, SC in practice
UV strength on this page follows solar elevation, ozone thickness, cloud cover, altitude, and surface reflection. Snow can bounce back most of the UV that hits it, water and sand far less, but all of them add to the dose skin receives.
Burn-time figures come from minimal erythemal dose (MED) values published for each Fitzpatrick skin type, divided by the erythemal irradiance at a given UV index. Personal MED varies by roughly 20 percent, so treat every number as a planning range.
Reapplication matters more than the SPF number. Reapply roughly every two hours outdoors and immediately after swimming, heavy sweating, or towelling, regardless of what the bottle claims.
Cumulative dose drives photoaging and long-term skin damage more than any single day. Small daily exposures on commutes, walks, and driving add up across a season.
Plan outdoor blocks around the peak UV window, usually between 10am and 4pm local time. Shade, UPF fabric, a wide-brim hat, and UV-blocking sunglasses reduce dose more reliably than sunscreen alone.
UV scale reference
The WHO scale groups UV 1-2 as low, 3-5 as moderate, 6-7 as high, 8-10 as very high, and 11 or above as extreme. Protection is recommended from UV 3 upward, and shade during the middle of the day becomes the priority from UV 8 upward.
A practical routine at moderate-to-high UV is roughly one ounce of broad-spectrum sunscreen for full-body coverage, applied 15 minutes before going out, then reapplied on schedule. Clothing, hats, and shade carry the rest of the load, especially for children and anyone with a history of easy burning.
Keep exploring DermUV
These pages give more depth around uv index charleston, sc, from UV-scale reference material to calculators and city forecasts.
- Tan vs burn calculator
- UV and sunscreen calculators
- DermUV articles
- UV and sunscreen glossary
- UVB definition
- vitamin d lesson
- UVA definition
- What UV index 5 means
- altitude lesson
Numbers are modelled, not measured at your exact location, so treat them as guidance for planning rather than exact thresholds.