Using BigQuery: Compare today's weather against the same date historically

It's my first time playing around with Google's BigQuery, and I'm pretty happy with the result so I figured I'd share....

The data is sourced from the NOAA GSOD dataset, which goes back to about 1929 at best. I tried to use the NOAA GHCN dataset, which from memory goes back as far as the 1700s, but even using BigQuery, it takes about 40 seconds to run the analysis, so isn't very user friendly :(

All in all, it's a pretty amazing service.