These are astronomical seasons but around the world the much more usefull definition is a (annually) repeating weather pattern. There are rain and dry seasons that may be related to the monsoon rains or may be related to wind patterns pushing clouds away from/to a place. The amazon has wet/dry seasons (not rain season) that describe the water level and is dependent on the rain in the Andes mountains and not the monsoon rains...
Nobody cares if "today is the astronomical start of summer" if it is still cold and rainy. You say summer starts when it gets hot and dry (apply your regional variant of summer here).
The landlords needs to give a written notice to the tenants at least 24h before they can give permission to the vampire. And the landlord needs to be present as well. Unless the vampire is a registered repair man, then the notice is enough.