So I completely wasted my time the last few hours and wrote a command-line-based PHP script that fetches the weather from wunderground.com, parses the resulting HTML file, and outputs the results on the command line. This is a lot like what some Eggdrop scripts do (and they even get the output from the same site). The result looks like:

pellis@localhost(~): weather 98296

Forecast for Everett, Washington (98296; as of 4:53 PM PST on December 22, 2004):
Currently 39F | Humidity: 100% | Dew Point: 39F | Wind: North at 0 mph
Pressure: 30.52 in | Conditions: Clear | Visibility: 10.0 miles | Sunrise/Sunset: 07:55 AM (PST)/04:19 PM (PST)

A completely worthless use of my time, but an interesting exercise. I may end up using this.