In northern parts of the world, snow usually makes caching a lot harder during the winter months.
So here is a reason to head out.
All you have to do is to log a cache each individual date (year doesn't matter) during the winter months of December, January and February (feb. 29th excluded).
The actual placement is T1 for a tall person, T4 for a short person.
Therefor the cache is rated T3.5.
This is a challenge cache
A challenge cache means that the container is at the posted coordinates, but to be able to log it as a find you have to fulfill certain requirements.