This is a variation of fkleon's temperature.sh script that puts the info in a simple text file instead of an email. It is also my first gist on github. :)

templogger.sh

#! /bin/sh

# This is your log filename
LOGFILE=/path/to/temp.log

# Create empty file 
touch $LOGFILE

# Define adastat function, which writes drive activity to temp file
adastat () {
  CM=$(camcontrol cmd $1 -a "E5 00 00 00 00 00 00 00 00 00 00 00" -r - | awk '{print $10}')
  if [ "$CM" = "FF" ] ; then
  echo " SPINNING" >> $LOGFILE
  elif [ "$CM" = "00" ] ; then
  echo " IDLE" >> $LOGFILE
  else
  echo " UNKNOWN ($CM)" >> $LOGFILE
  fi
}

# Write some general information
echo System Temperatures - `date` >> $LOGFILE
cat /etc/version >> $LOGFILE
uptime | awk '{ print "\nSystem Load:",$10,$11,$12,"\n" }' >> $LOGFILE

# Write CPU temperatures
echo "CPU Temperature:" >> $LOGFILE
sysctl -a | egrep -E "cpu\.[0-9]+\.temp" >> $LOGFILE
echo >> $LOGFILE

# Write HDD temperatures and status
echo "HDD Temperature:" >> $LOGFILE
for i in $(sysctl -n kern.disks | awk '{for (i=NF; i!=0 ; i--) if(match($i, '/ada/')) print $i }' )
do
echo -n $i: `smartctl -a /dev/$i | awk '/Temperature_Celsius/{DevTemp=$10;} /Serial Number:/{DevSerNum=$3}; /Device Model:/{DevVendor=$3; DevName=$4} \
END {printf "%s C - %s %s (%s) - ", DevTemp,DevVendor,DevName,DevSerNum }'` >> $LOGFILE;
adastat $i;
done

# Make a seperator
echo " " >> $LOGFILE
echo "###############################################################################" >> $LOGFILE
echo " " >> $LOGFILE

exit 0