In order to get that density altitude at 3100' and 49C the QNH would have to be about 0950. So either you happened to be in the eye of a hurricane when you made that measurement, or your GPS was wrong, or you interpreted it incorrectly. At a QNH of 1013 and a dew point of 15 the temperature needed to get 9,300 feet is 66C, equally unlikely. I'm not making this up just to be a dick, you can plug the numbers into an E6B or you can use one of the many online density altitude calculators and you will come up with the same results.