Oy. The unit of heating/cooling temperature comparison is the degree-day, not the average temperature of the month.
For each time period, take the difference from your desired temperature. If you have an acceptable range, take the difference from the near edge of that range.
e.g. with a desired range 65-75, a 40 degree day counts as negative 25 and a 90 degree day counts as positive 15.
Keep track separately of positive and negative.
Now you have a record of how much you needed to cool or heat. Local newspapers -- remember those? -- will usually keep track for you on their weather page.
That's a suitable basis for comparison. Not monthly average temperature, not average high, not average low.
>Now you have a record of how much you needed to cool or heat. Local newspapers -- remember those? -- will usually keep track for you on their weather page
Yahoo! has a great free weather API with historical data, as does NOAA.
For each time period, take the difference from your desired temperature. If you have an acceptable range, take the difference from the near edge of that range.
e.g. with a desired range 65-75, a 40 degree day counts as negative 25 and a 90 degree day counts as positive 15.
Keep track separately of positive and negative.
Now you have a record of how much you needed to cool or heat. Local newspapers -- remember those? -- will usually keep track for you on their weather page.
That's a suitable basis for comparison. Not monthly average temperature, not average high, not average low.