The images are all static images; and the weather page links to the appropriate one; so I can't just link through to the image. So, instead, I put <img style="margin-left: 10%;" src="http://www.chiark.greenend.org.uk/ucgi/%7Ejdamery/weather?" height="65" width="80"> where weather is the following shell script:
wget -q -O - --load-cookies ~/var/lib/weather/bbcw.cookie.txt "http://www.
bbc.co.uk/weather/" | grep 'symbol.*summary' | sed 's¬.*src="\([^"]*\).*¬S
tatus: 302 Found\
Your browser should have been redirected to a weather glyph.\