A simple command to check the weather in a region:
EvalRgnWeather = <RegionUID>;<Operator>;<Value>
Value can be between 0 and 4, or an alias:
see in aliases the file various.ini:
// Weather types
$Fair = 0
$Mud = 1
$Snow = 2
$HarshWeather = 3
$VHarshWeather = 4
Operator is one of
=
<=
>=
<
>
DICE
as usual with all evals commands.