Folks, here are the average temps for the Tamworth area for the last week of February and early March 2014 (based on historical data of course):
http://www.accuweather.com/en/au/tam...-weather/12773
As Lake Chaffey is alittle further east in the ranges and higher in altitude the temps maybe lower than those shown (slightly).
Certainly the averages indicate that it will be both comfortable for day time lake activities, and cool enough at night to be enjoyable for astronomy and sleeping.