The Winter Sun Myth: Why Skin Cancer Doesn't Care About the Season
- Doctor Dermis
- Jul 17
- 4 min read
A common misconception in public health is that the risk of skin cancer drops along with the temperature. When the weather cools, many Australians put the sunscreen away, assuming that if it’s not hot,it can’t be doing skin damage.
However, temperature and ultraviolet (UV) radiation are two completely different things. Temperature is about infrared heat - it’s why you feel warm or cold. UV radiation is invisible, and it damages your skin at a cellular level no matter what the thermometer says.
That’s a big reason skin cancer rates in Australia stay high, even during winter.
The Science: UV Radiation vs. Temperature
Winter sun safety is often misunderstood because UV radiation cannot be seen or felt.
Infrared Radiation (heat): changes a lot depending on cloud cover, wind, and the seasons
Ultraviolet Radiation (damage): depends on the sun’s angle and the thickness of the ozone layer - not the weather!
So while temperatures can drop sharply in winter, the sun's angle across most of Australia remains high enough to deliver high levels of UV radiation and pose a risk of skin damage.
According to data from the Bureau of Meteorology (BOM) and the Cancer Council, sun protection is recommended whenever the UV Index reaches 3 (Moderate) or higher. At that level, UV radiation is strong enough to damage unprotected skin cells and lead to the development of both melanoma and non-melanoma skin cancers (such as Basal Cell Carcinoma and Squamous Cell Carcinoma).
UV Index by City: Winter Sun Protection Across Australia
Because Australia is such a large country, winter looks completely different depending on where you live. The closer you are to the equator, the less variation there is in UV levels between seasons.
Fun fact: Melbourne and Hobart are the only Australian capital cities where average winter UV levels consistently stay below 3 (the point at which sun protection becomes necessary), during June, July, and August.
City | Average Winter Maximum UV Index | Do I Need Sunscreen in Winter? |
Darwin | 8 - 10+ (Very High) | Yes - daily SPF, all year round, is needed. |
Brisbane | 4 - 5 (Moderate) | Yes - daily protection is needed. |
Perth & Sydney | 3 - 4 (Moderate) | Yes - frequently hits damage levels around midday. |
Adelaide & Canberra | 2 – 3 (Low to Moderate) | Variable - check the UV index on clear days |
Melbourne & Hobart | 1 – 2 (Low) | Usually not - except when outdoors for long periods, or at high altitudes. |
The Altitude and Snow Reflection Exception: Heading to the snow? UV radiation increases by approximately 10%-12% for every 1,000 meters of altitude. And, fresh snow reflects up to 90% of UV rays - so on the slopes, you could be getting nearly double the exposure from reflection of the snow.
Cumulative Damage: Why Small Sun Exposures Add Up
Skin cancer is rarely caused by one bad sunburn. It’s usually the result of cumulative UV exposure - small, unprotected doses of sun exposure that build up over a lifetime.
Walking the dog, gardening, or eating lunch outside on a winter’s day all add up to that total. Because you don’t feel the heat in winter, it’s easy to stay outdoors longer without protection. That means DNA damage can build up in your skin without you ever noticing - or getting burnt. This kind of low-level, non-burning (sub-erythemal) exposure is a major cause of Squamous Cell Carcinomas (SCC) later in life.
How to Keep Skin Safe From the Sun During Winter: Your Adjusted Winter Action Plan
Winter sun safety doesn’t mean copying your summer routine - it just means knowing what to actually check.
Check the App, not the weather: Don’t rely on the weather forecast; check the live UV index through the Bureau of Meteorology or the SunSmart app. Make it a habit to check the "sun protection times" for your specific location.
Watch the midday hours: In winter, dangerous UV levels are squeenzed into a shorter window - usually between 10:00 AM and 2:00 PM. If the UV index is forecast to reach 3 or higher during these hours, apply a broad-spectrum SPF 50+ sunscreen to exposed areas such as the face, neck, and hands before heading out.
Don't skip moisturiser with SPF: On lower-UV winter days, a daily moisturiser or makeup with SPF 15–30 built in is often enough for everyday errands - saving the heavier SPF 50+ sunscreen for extended time outdoors.
Reapply if you're outdoors for long periods: Sunscreen breaks down over time, even in winter. If you're gardening, walking, or in the snow for more than two hours, reapply every two hours as you would in summer.
Book a professional skin check: Winter is actually one of the best times to get a full skin check, since new spots or changes are easier to spot without a summer tan masking them. Book a skin check with our clinic to catch anything early.
Your skin can’t tell the difference between summer UV and winter UV. So, instead of checking the temperature, start tracking the UV index.
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