My SSD becomes dangerously hot (leading to system freeze), I know, because smartd reported:
Device: /dev/sda [SAT], SMART Usage Attribute: 190 Airflow_Temperature_Cel changed from 70 to 71
 
That is why I tried to monitor its temperature, but this did not succeed with hddtemp, after installing hddtemp a run gave this:
 
$ sudo hddtemp /dev/sda

WARNING: Drive /dev/sda doesn't seem to have a temperature sensor.
WARNING: This doesn't mean it hasn't got one.
WARNING: If you are sure it has one, please contact me (hddtemp@guzu.net).
WARNING: See --help, --debug and --drivebase options.
/dev/sda: Samsung SSD 850 EVO 500G B �@: no sensor
 
So the temp-sensor is there, but it is not recognized, hopefully it can be included...