Hi, Clear fluid from nose is at least a good sign that there is no active bacterial infection hence the cause looks to be an allergic. Humid atmosphere may not have much effect on sinusitis if it is due to allergy and such thing is always treatable although may not be curable. Allergens that is causing the clear water excretion from nose an be found out by you and your family members on close observation. This can be anything under the sun hence keen observation only helps. It is always better to get an opinion of an ENT Surgeon, CT scan of sinuses and relevant tests of blood. This can be of help for specific treatment. Another best way is to get shifted to the area for a few days to see whether the atmosphere there suits you, helps to relieve symptoms or enhances the problems to take a decision. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. T. Chandrakant, General Surgeon