It is completely normal.
If the first measured temperature (24 Celsius) matches the room temperature AND then you see the temperature increasing when the drive is working, we can say the temperature sensor is working as should and provide accurate results.
30-31 Celsius is excellent level. Usually external drives have higher temperatures but if there's a fan, it keeps the drive in this good temperature range.
Maybe if you perform disk testing (Disk -> Extended self test in Hard Disk Sentinel) or a virus scan / defragmentation, you will see some increase in the temperature but I suspect it will be still nice, thanks for the fan.
maverick wrote:I tried to calibrate temperature of my hard drive. After 8 hours powered off my computer, when I power on I noticed that the temperature is 24 celcius with same my room temperature. After 5 minutes it is increased to 27 celcius degree.
Usually my drive (seagate 1 terabyte-sata3-ncq) works at 30 - 31 celcius degree although it has a external hard drive fan.
Is it normal ?