the temperature of my CPU's cores have been recently getting hotter during summer, reaching a max temperature of 91 degrees Celsius. I have an Intel core i7 3770 at 3.4 GHz. I'm only new to this computer business so i don't really know much about this topic. Thank you
I would be a little worried about 90C in Summer, but what are the outside temperatures where you are in Summer. If you are using the stock cooler that came with the processor, I would have a good think about upgrading to something like an Arctic 7 Pro as that will prolong the life of your CPU for less than $25/£15.
I myself would be worried if my CPU reached 90+ degrees. Did you build the computer yourself? If yes you should feel comfortable enough changing the thermal paste or swapping your stock cooler for something better like the CM Evo212. If you are not comfortable removing parts inside your computer then you could watch some guides on how to do it.
The best thing would be to do both, change your Thermal Paste and swap to a better cooler.
Good luck : )