For regrets (using "wish") about continuous events in the the future, we use "was/were going to be -ing". e.g. I wish it wasn't going to be raining all day tomorrow. In practice, it would be more common to say, "I wish it wasn't going to rain all day tomorrow." The most common use of the future continuous is for talking about continuous activity at a time when a single event happens. So you could say e.g. : "I wish it wasn't going to be raining tomorrow around 11am when the bride and groom are due to leave the church." I have to say that I rarely hear this construction and, generally, regrets about things which will start in the future are rare.

Hi there. No, you cannot use it with the future continuous. You can use it with past perfect continuous, though. E.g. I wish it had ot been snowing when we visited the park. However, it is more common to use the past perfec in most situations: I wish it had not snowed when we visited the park.