Yes there are UV rays at night but at very low intensities. So, if you are planning on getting a sun tan that almost certainly is impossible at night.
Below we will go into more detail on UV rays at night and other factors such as if moonlight is a UV light.
Explaining UV Rays at Night
As there is no direct sunlight at nighttime the vast majority of UV rays are gone at night though there can still be a small amount of UV even at night.
One of the ways you can get a little UV at night is from UV rays that are reflected by our atmosphere. What that basically means is some UV rays are reflected back into space by the Ozone layer.
What also can happen is some UV rays reach earth and are absorbed by the ground, though there are some which are reflected back into the atmosphere and then basically they reflected back again to the ground.
In the early part of the night the process is more likely but the longer the night goes the less this will have an effect. It’s also worth mentioning that these reflected rays are much less intense than the rays when they first arrived.
Sometimes also what can happen is the moon giving UV light. This sometimes leads to the question is the moon a UV light?
Well, no moon itself does not emit any UV light and is not a UV light. But at night the sun can light up the moon making it appear bright. A somewhat similar process then happens where some UV light is reflected off the moon and to earth at nighttime. Admittedly it is very low but there is still a very small amount of UV.
What Time of Day Do UV Rays Stop?
Technically UV rays do not stop at all but go to an extremely low level at night-time. This is typically at least an hour after the sun sets. If we were rounding the UV index at night it would always be 0 as the amount would almost always be very little.
Are There UV Rays After Sunset?
Yes, there are UV rays after sunset. The UV rays will be low even at the start of sunset, and as time passes after sunset their levels will drop even more.
Why is There No UV Light at Night?
There is a very small amount of UV light at night-time though the amount is almost negligible. The reason for this is because the sunlight rays are no longer reaching the surface of earth at night-time and the sun is the primary source of UV rays on earth.