I actually discovered this by accident one day while out shopping. I purchased my shea butter and left it in the car all day long. When I got home my shea butter was completely melted. I put in a cool space in hopes that it would harden and it did (I didn't know much about shea butter back then).
So now every summer I melt my shea butter by placing it in the car (windows up) and let it sit all day. I usually do this on a day that is 90° or higher. It's been around 100° here lately so the shea butter melted fast.
I like melting shea butter this way because when it hardens, it's more creamy than stiff. I don't like using the stove-top or the microwave because the shea butter is always grainy when it hardens and it still has the same stiffness after using either of those melting methods.
Below, the top pic is of the shea butter before placing it in the car. The bottom pic is of the shea butter after it cooled in the house. Even if you only use shea butter in your mixes, melting it makes it easier to measure out for use.
Got any tips to share? Comment below.