Jalapeño and Confused GB: thanks for the additional info, including the variants of the original query, but it wasn't necessary, I was already persuaded by the earlier opinions.
What I was addressing in my 08:12 post was just the care needed in using SE hit counts as evidence. Whether it's 348 hits or 20,000 hits has no importance by itself, rather, one must ask, compared to what?
In my case, the 348 for "it's bucketing down" was to be compared to 93,400 for "it's raining cats and dogs". It's a very good idea to vary the query, and I commend you for doing so--such as trying "bucketing down" without the it's; but then that should be compared to "raining cats and dogs" (400,000). Finally, we should all keep in mind the vastness of the internet, and how common typos and even patent nonsense can have a certain number of hits, which doesn't prove anything one way or the other.
I've long believed that SE hit counts are thrown around a lot on Leo as proof of something, without a full understanding of how best to interpret them. Hence my request for people to use them with caution. I fully agree that "bucketing down" should be kept, based on the native opinions expressed here. My point was only, "no need to bring SE counts to bear in order to convince me about "bucketing" but if you do, please use them with care". That's all I wanted to suggest.