There's a specific kind of morning where the sky is grey, the hat stays on the hook by the door, and everyone heads out feeling like they've dodged a chore. Then someone comes home a bit pink around the nose and ears, and the questions start. Grey skies feel like a day off. They usually aren't.
The number that changes the habit
Cloud cover looks like it should be doing more than it actually does. Depending on the type and thickness of the cloud, a good deal of UV radiation still gets through, and on a lot of overcast days it's a lot more than people expect, sometimes up to around 80% of it, according to Cancer Council Australia's UV guidance. Thin or scattered clouds barely slow UV down at all. It's the thick, dark storm-grey cloud that actually cuts a meaningful amount, and that's not the kind of day most people are outside in any way.
Why "it doesn't feel sunny" is the wrong signal
Here's the part that trips people up: heat and UV aren't the same thing, and they don't move together. The warmth you feel on your skin is mostly infrared radiation, and that's what clouds are genuinely good at blocking. UV is a completely different wavelength, and it travels through clouds far more easily. So a cool, overcast day can carry a UV index just as high as a warm, clear one. Temperature is telling you how the day feels. It has nothing to do with what's actually reaching skin.
Some cloudy days are trickier than clear ones
There's an odd twist to this too. Scattered or broken clouds can occasionally push UV levels higher than a completely clear sky, not lower, because sunlight bounces and scatters off the edges of clouds on its way down. It's a small effect and it doesn't happen every day, but it's one more reason the sky's appearance is a genuinely unreliable guide to how much UV is around.
What this actually means day to day
The useful habit isn't checking whether it's sunny. It's checking the UV index, which the Bureau of Meteorology publishes daily and which stays useful on cloudy days precisely because it isn't guessing off appearances the way we are. Once the UV index sits at 3 or above, which covers most of the day across most of the year in Australia, cloud cover or not, it's a hat day. Stay shaded even under the clouds, and our UV Guide breaks down how to read that number properly and what it actually means for time outside.
Where the hat comes in
Here's the thing about a hat: it doesn't check the forecast first. It sits between UV and skin whether the sky's doing its brightest blue or its flattest grey, which makes it one of the only parts of a sun routine that isn't quietly relying on someone reading the weather correctly. We rate every fabric UPF 50+ for exactly this reason, cloudy included, because the fabric doesn't know what day it thinks it's having.
If you want the deeper version of what that number's actually doing, we broke it down properly in What Does UPF 50+ Actually Mean? A good fit matters just as much as the fabric though, since a hat sliding around isn't shading anything. Find Their Fit sorts that out in about a minute. The full Play Range carries the same rating across every colour, backed by our money-back guarantee if it isn't pulling its weight.
Grey sky, same hat, same habit either way.
Frequently Asked Questions
Can kids still get sunburnt on a cloudy day?
Yes. UV radiation passes through most cloud cover far more easily than people expect, and a fair amount can still reach skin even under a fully overcast sky. Sunburn depends on UV levels, not on how bright or warm the day feels.
Does temperature tell you anything about UV levels?
Not really. Heat comes mostly from infrared radiation, which clouds block reasonably well, while UV travels through clouds far more easily. A cool, overcast day can carry a UV index just as high as a hot, clear one, so temperature isn't a useful guide either way.
What UV index means a hat is worth wearing?
Once the UV index reaches 3 or above, it's worth treating like any sunny day, hat included. That threshold gets hit on most days across most of the year in Australia, cloudy or not.
Do all types of cloud block the same amount of UV?
No. Thin, light, or scattered clouds let through the large majority of UV, while thick, dark storm clouds block a meaningful amount. Most everyday overcast weather sits closer to the thin end of that range than people assume.
Related posts:
What Does UPF 50+ Actually Mean? · Hats vs Sunscreen for Babies: What Actually Works Under 12 Months
Cloudy Days Are a Hat Day Too
There's a specific kind of morning where the sky is grey, the hat stays on the hook by the door, and everyone heads out feeling like they've dodged a chore. Then someone comes home a bit pink around the nose and ears, and the questions start. Grey skies feel like a day off. They usually aren't.
The number that changes the habit
Cloud cover looks like it should be doing more than it actually does. Depending on the type and thickness of the cloud, a good deal of UV radiation still gets through, and on a lot of overcast days it's a lot more than people expect, sometimes up to around 80% of it, according to Cancer Council Australia's UV guidance. Thin or scattered clouds barely slow UV down at all. It's the thick, dark storm-grey cloud that actually cuts a meaningful amount, and that's not the kind of day most people are outside in any way.
Why "it doesn't feel sunny" is the wrong signal
Here's the part that trips people up: heat and UV aren't the same thing, and they don't move together. The warmth you feel on your skin is mostly infrared radiation, and that's what clouds are genuinely good at blocking. UV is a completely different wavelength, and it travels through clouds far more easily. So a cool, overcast day can carry a UV index just as high as a warm, clear one. Temperature is telling you how the day feels. It has nothing to do with what's actually reaching skin.
Some cloudy days are trickier than clear ones
There's an odd twist to this too. Scattered or broken clouds can occasionally push UV levels higher than a completely clear sky, not lower, because sunlight bounces and scatters off the edges of clouds on its way down. It's a small effect and it doesn't happen every day, but it's one more reason the sky's appearance is a genuinely unreliable guide to how much UV is around.
What this actually means day to day
The useful habit isn't checking whether it's sunny. It's checking the UV index, which the Bureau of Meteorology publishes daily and which stays useful on cloudy days precisely because it isn't guessing off appearances the way we are. Once the UV index sits at 3 or above, which covers most of the day across most of the year in Australia, cloud cover or not, it's a hat day. Stay shaded even under the clouds, and our UV Guide breaks down how to read that number properly and what it actually means for time outside.
Where the hat comes in
Here's the thing about a hat: it doesn't check the forecast first. It sits between UV and skin whether the sky's doing its brightest blue or its flattest grey, which makes it one of the only parts of a sun routine that isn't quietly relying on someone reading the weather correctly. We rate every fabric UPF 50+ for exactly this reason, cloudy included, because the fabric doesn't know what day it thinks it's having.
If you want the deeper version of what that number's actually doing, we broke it down properly in What Does UPF 50+ Actually Mean? A good fit matters just as much as the fabric though, since a hat sliding around isn't shading anything. Find Their Fit sorts that out in about a minute. The full Play Range carries the same rating across every colour, backed by our money-back guarantee if it isn't pulling its weight.
Grey sky, same hat, same habit either way.
Frequently Asked Questions
Can kids still get sunburnt on a cloudy day?
Yes. UV radiation passes through most cloud cover far more easily than people expect, and a fair amount can still reach skin even under a fully overcast sky. Sunburn depends on UV levels, not on how bright or warm the day feels.
Does temperature tell you anything about UV levels?
Not really. Heat comes mostly from infrared radiation, which clouds block reasonably well, while UV travels through clouds far more easily. A cool, overcast day can carry a UV index just as high as a hot, clear one, so temperature isn't a useful guide either way.
What UV index means a hat is worth wearing?
Once the UV index reaches 3 or above, it's worth treating like any sunny day, hat included. That threshold gets hit on most days across most of the year in Australia, cloudy or not.
Do all types of cloud block the same amount of UV?
No. Thin, light, or scattered clouds let through the large majority of UV, while thick, dark storm clouds block a meaningful amount. Most everyday overcast weather sits closer to the thin end of that range than people assume.
Related posts:
What Does UPF 50+ Actually Mean? · Hats vs Sunscreen for Babies: What Actually Works Under 12 Months