I finally got around to putting the current weather back in the blog. This was the one major cleanup from when I switched to Drupal almost two years ago.
It isn't especially elegant: at home I have a Mac Mini running Lightsoft Weather Center; this downloads the current weather from my Davis Vantage Pro weather station. Every 15 minutes, it updates an HTML template and FTPs it as a static file to my web hosting provider. This static HTML page is included on every page of the site through an iframe.
There are also some history graphs which can be accessed by clicking the "Weather in the Frozen North" link; those are also updated every 15 minutes.
I was forced to abandon the Davis WeatherLink software because the Mac version was simply pathetic--it has not been well maintained, and ran as a Java application which seemed to be very brittle. Fortunately, there are now several superior alternatives for weather station software on the Mac which have more features, are easier to set up, and produce nicer-looking output.