I have always wondered what type of measuring equipment is used when they measure -75 to -100 are colder temps. Most home use temps don't go that low or perform well in the minus ranges. The record cold temp here was 8 degrees and the high was 111 degress, very rare to get into the 100's in the summer and near 20 in the winter so nearly all measuring devices work just fine.
the sht31 temp appears to really be the strong point of the sensor and the humidity the weak point, too bad, could really be a great sensor otherwise.