i7tt is a nice CPU temperature monitor. It draws each core in line chart in Braille and groups all cores in a bar chart for overview, which uses different colors to indicate the temperature ranges.
There is only one command-line option for average period. It uses coretemp drivers sysfs interface to get the data.
i7tt was created by Marios Andreopoulos on 2015-08-19, written in Go with termui under the GPLv3, currently git-3335dbb (2015-11-20, post v1.03 (2015-08-28)).