Here some temperature data for January of this year (that's mid summer for us) for my drying shed (a vented seatainer) which as about 2/3rd full of timber slabs when these readings were made
Firstly a couple of explanations.
- The red line shows the air temperature in the middle of the inside of the shed.
- The blue line shows the outside temperature of the shed in the sun - its effectively the skin temperature of the seatainer (I place a temp sensor inside a steel box attached to the outside of the shed).
- the Orange line shows the daily max temp - you can see we had quite a few days above 90F, and 5 days above 100F
- The Green line shows the daily min temp. It never went below 50F and was generally above 60F overnight.
Some observations:
The highest temperatures are the skin temp of the shed which reached 55ºC (131F) on a day when it was 41ºC (106F) outside air temp.
The maximum air temp inside the shed is always greater than the daily maximum by ~7ºC (13F) but never more than the skin temperature.
The shed air temp never gets outrageously hot - The hottest it got to was just 46ºC (115F) when it was 41ºC (106F) outside. I could probably boost that by reducing the air extraction (two full sized whirly birds or self powered roof mounted fans)
The lowest temperatures of the skin are equal to or slightly more than the overnight minima,
The minimum air temp inside the seatainer is ~5ºC (9F) greater than outside air temp.
This is an excellent demonstration of how a shed full of timber acts as a buffer against low and high container temperatures.
What I should be showing you is the RH data - it drops to less than 20 during the day but shoots up like a rocket during the night to over 90% when the air temp drops because the timber is still toasty warm and as I said in my first post, this rise in RH during the night helps the wood recover from the stress of drying out in the day and reduces splitting. This would be not good for thin boards but seems to be fine for 2"+ slabs for most wood because there does not appear to be much splitting.