I’ve written a Ruby script called bbc-weather.rb that parses the BBC weather RSS for a particular location and formats the data for conky. Here’s an example:

To use it insert the following in your .conkyrc:

${execpi 600 ruby /path/to/bbc-weather.rb 4197}

This will refresh every hour. Replace 4197 with the number of your local weather station. You can find this by looking at the BBC weather URL which is of the form weather/forecast/XXXX. You also need to define two colours for the script to use, in the options section before TEXT, like so:

color1 white
color2 grey

You might also need the following, as conky limits the about of text it will read from a sub-process:

text_buffer_size 2048

UPDATE: apparently this script no longer works with recent BBC Weather updates. Check out the comments for an improved version.