Re: why would rain affect sinus pressure?

I think that you have just about figuered it out, you just need to think a 
little more about the atmospheric pressure. Storms are often preceeded by 
a fall in atmospheric pressure. You can check this out yourself by 
following the pressures reported by your local weather service, a home 
barometer or the local newspaper.

The sinuses are empty spaces in the bones of the face, head and nasal 
passages. The pressure of the air in the sinuses should be in equilibrium 
with atmospheric pressure. If inflammation or infection causes obstruction 
to the mechanisms that allow for equilibrium to be maintained then when 
the atmopspheric pressure falls the air in the sinuses expands and causes 
an increase in pressure within the sinuses. That is possibly what causes 
the "sinus headache". The same thing can happen when going up in an 
airplane or maybe even to the top of a high building. 

You could do an experiment. You keep a record of the daily pressures and 
storms, and your mother keep a record of when she has her sinus headaches, 
then compare the two. If it does not correspond then you will have to look 
for another reason. Maybe it just seems as though she can predict the 
weather, but when you keep a record maybe there is no correspondence. You 
just remember all the times it correctly predicted a storm but have 
overlooked all the times it didn't. Become a MAD Scientist yourself.