This summer, I insulated the roof of my wooden yurt/milk barn. I'm finally getting around to writing it up.
Here are the daily temperatures from nws.noaa.gov:
June 29 - 88/58
June 30 - 97/57
July 01 - 88/66
July 02 - 97/58
July 03 - 84/67
July 04 - 90/52
http://www.nws.noaa.gov/climate/index.php?wfo=boi
I installed the insulation on July 1.
Notice how the highs and lows evened out after the insulation was installed. The high on June 30 and July 2 was the same, but the high inside went from 96 down to 85 degrees. (I used a Lascar EL-USB-1 temperature logger to record the inside temperature.)
Now that it's getting colder, I'm going to check the temperatures again, just for kicks.