Airline fares will typically change at 90, 30, and 15 days before a given flight, based solely on demand for the flight. As in, if the flight is full or more full than they expected, then prices for any remaining seats may jump a fare class. However, airlines hate empty flights, so if they flight is emptier than they were expecting, then they'll reduce fares, but only to a point. Also, if a flight is selling really well, then seats may jump a fare class automatically. All in all, fares fluctuate based on demand, and demand alone.
This is all going to say that you should get familiar with the different fare classes that the airline offers, and buy if the offered fare class is low. (For example, with Delta the "low" fare classes are L, U, T, and E, while the "high" classes are Y [full fare], B, M, K, and Q.)
Now, inclement weather can affect demand for flights surrounding the dates of the storm, and can thus drive prices up, but this typically only lasts 5-10 days, not a full month.
Also, almost none of the above applies to pleasure-travel airlines, like Southwest or Allegiant, as they typically don't sell many seats closer than 30 days out, and don't have nearly as many fare classes as larger airlines do. With those airlines, you typically will not see any decrease in price over time.