I think it's a normal temperature if you are watching a video or a resource intensive website. Anyway, I recommend you to install tlp (
sudo apt install tlp) because this app is going to help with your issue. TLP is basically a daemon that monitors different sensors and is able to modify hardware settings so that your system becomes more efficient (and makes the temperatures lower).
After you install it, do
sudo tlp start to start it and
sudo tlp-stat to see the current settings.
To lower the temperatures, the best thing you can do is apply the settings below, run the first command and check if your settings are the same.
If the output is different you can change the settings with
sudo pantheon-text-editor /etc/default/tlp. Don't forget to start tlp again to apply the new settings.
sudo tlp-stat -p
scaling_driver = intel_pstate
scaling_governor = powersave
Now, this other settings you have to change them in
/etc/default/grub . After that, run
sudo update-grub and reboot. Some of the following may not be available so just change the ones that are.
sudo tlp-stat | grep /sys/module/i915/parameters/
/sys/module/i915/parameters/powersave = 1
/sys/module/i915/parameters/enable_rc6 = anything between 3-7 **
/sys/module/i915/parameters/enable_fbc = 0
** 7 is the most agressive and may make your videos stutter.
That's all. If it's necessary i can provide more explanations as to why I've chosen this settings. But basically I've just set your cpu settings to recommended and your intel graphics settings to a powersave mode.