Sentence Correction

Analysts blamed May's sluggish retail sales on unexciting merchandise as well as the weather, colder and wetter than was usual in some regions, which slowed sales of barbecue grills and lawn furniture.
1.colder and wetter than was usual in some regions, which slowed
2.which was colder and wetter than usual in some regions, slowing
3.since it was colder and wetter than usually in some regions, which slowed
4.being colder and wetter than usually in some regions, slowing
5.having been colder and wetter than was usual in some regions and slowed
OA:2
I totally understand how the OA is 2 and I myself got it right.
I narrowed down to choices 2 and 4 and then I saw that 4 has a wrong adveb usage:usually
The confusion here is that, if in 4, the choice had been
being colder and wetter than usual in some regions, slowing
i.e. I replaced usually with usual and now the only difference between 2 and 4 is the use of which and being, what would have been the better choice ?

Can anybody clear this confusion.

Thanks.