Your specific request is a bit at odds with the traditional role most of these Saints have played.
is the patron Saint against cold weather.
is considered the patron Saint against bad weather/for rain.
Interestingly, he may have been the first to celebrate a version of Groundhog Day:
Agricola of Avignon
Legend has it that if it rains on his feast day, the next 40 days will be wet; if the weather is good, the next 40 will be fine as well.
is the patron Saint for rain and good weather.
There is Clare of Assisi
, but I couldn't find anything in her biography to indicate why she is associated with weather, or any specificity as to what weather.
More promising is Eurosia
, who according to the link is apparently the Saint for furious hail, but unfortunately also of frightful waters.