Is 118 degrees in the attic on a day with 102 degrees outside a reasonable temperature?

That is very reasonable. And you are right, I have read studies on attics reaching 190 degrees. 118 with it being 102 is awesome I say! you must have some radient barrier of some kind.

Probably not 150, but you can expect your attic to be at least 25-30 degrees hotter on a hot day. If it concerns you, install an attic fan. It sucks out all the hot air and helps keep the house cooler.

Depending on what part of the U.S.A. you live in (having almost straight, direct bearing of bright sunlight on your roof for the major number of hours of any given day) and the reflectivity or absorbancy of heat throughout that time of exposure by the roofing material and subsequent coverings of the attic, temperatures of as high as 150 degrees F. and more can easily be reached in attics without any ventillation being provided.

I have measured the temperature in all seasons in attics while installing units.140f is the hottest that I have ever measured.In Houston Texas in August.You can only work 8-10 minutes at a time before coming down for a couple of minutes it can be very dangerous.Your entire body feels like you got out of a swimming pool a second earlier.Wet!

I love to do an install in the cool months.Gravy!

Quite reasonable. Most attics get much hotter, like 150 degrees on a sunny summer day, if they don't have adequate ventilation.

Just installed an attic fan. It was 110 in the attic, morning, cloudy day with 80 degrees outside.

Absolutely. It will depend on the materials that the attic is constructed from and the amount of ventilation, but it would not be unreasonable for an attic to reach 150 on a day when it is 102 outside.

Yes I have attic vent fans that are set to turn on when it gets to 120 degrees. That usually occurs if the outside temperature reaches about 90 degrees.

if thats all it rises,your in good shape,i have been in attics at 7:00a when it was 80 out side and it was already over 100 in there,if you put an attic fan in there you can drop it even more it will also save on cooling cost.

that is not too bad, but not good for energy costs. that heat will transfer through the insulation and heat your ceiling in turn causing your ac to work harder. i suggest radiant barrier, increase ventilation, but watch out for power attic vents they can cause house to go negative pressure sucking cold air out of house into attic.

I incredibly plenty gave that up an prolonged time in the past. No Dusty, water boils at 212 stages. in simple terms on account which you reside in a position with a constrained variety of expression does no longer recommend all of us ought to swap over to the remedial maths version of measuring issues.