bitsostring,
Unfortunately Brian Underdown has discontinued supporting the weather display version of this script so he won’t be able to help. I assume that the max and min figures are taken from clientraw via the livedata.php script. I would have a look in their to see if that shows any issues. After that I would look at temperature.php which is the script used to produce the figures in the temperature module. I unfortunately don’t use that version anymore, so can’t help much.
Paul