Question about months of supply winter vs. summer

[Adam Sporinsky]

Hello all,

I have a question about how to figure out months of supply for an area.  I am trying to come up with this as suggested by @J Scott in the flipping book.  Right now however, it's March, the last month was Feb, which is not the greatest real estate month.  If I want to get the months of supply as number of houses on the market / monthly rate of houses sold, my numbers are going to be low for the rate being sold since the last 30 days were snowy.  

How should I be handling this?  Obviously, using values from last summer could be misleading if the market changed, but the last few months are misleadingly low due to being winter.  What would others suggest I use.

For instance, in the market I am analyzing tonight, the last 30 days saw 9 houses sold.  The last 90 days saw an average of 12.3 houses sold.  The last 6 months saw 14.3 average, and the full year shows an average of 17.25.  Should I average these numbers out? Should I use the 6 month average or the 3 month average, or an average of those two numbers or something?

Looking forward to hearing what people think.