I believe you are right, it's normal for weather to affect animal behavior. I have seen it too. I would ask questions like these:
What changes has the recent weather created in this room in my home?
Has there been a change of:
lighting?
barometric pressure?
O2?
CO2?
humidity?
temperature?
How could these changes have affected my animals?
Have I been paying more attention to my aquarium, or less?
Have I changed anything in my maintenance during this time?
Hope this helps.
Aloha