Generally, there should be no restrictions on IR training year round.
However, do remember 3 points:
> Is the aircraft your FTO uses de/anti iced ? Even though the vis might be fine, if your aircraft is not so equipped, you might have to remain on the ground.
> Does your base airfield have published approaches, with reasonable minimums ? Not being able to get back in can be rather expensive if you have to stop over at a larger airfiled.
> Does your base airfield have more than 1 runway which will keep you within your crosswind limits - Winds as well as vis can be a limiting factor.