I specifically bought HDThermometer because the reviews claimed it worked great for determining the temperature indoors. I tried it first as a free app but then read a comment that said to purchase it for it work fully, foolish me! I did, and I won’t make that mistake again! I literally held my phone next to a gas fireplace until I couldn’t stand the heat on my skin - no change! Then once it had cooled, I put it in the fridge, and surprise, surprise NO CHANGE. It may tell me what temperature it is in my city, but the FREE iPhone weather app will do that!! I wish o had seen a review like this one before purchasing - I never would have done it and have no clue how HDThermometer has a 4+ star rating for doing basically nothing. I’d get my money back if I thought it was worth my time to do so... I just deleted it instead and would give it 0 stars if possible.