Dew point is the tempurature the air cannot hold the weight of the water in it. The water then begins to condense and form droplets. This tempurature is always below or equal to the air tempurature.
Propane prices. Maine (ME) propane users spent an average of $2.724 per gallon over the 2012-2013 heating season. This is slightly higher than the 2.436 average for the country as a whole, for the reasons explained above (distance from major supply source, colder climate, higher demand).
At $2.81 (average price per gallon in winter 2011-2012) an American household using propane spends $1,300 on average and a family living in a 2200 square-foot house will pay between $3,372 and $4,215 per year: $140 for cooking, $140-281 for drying, $843-1,124 for water heating.