I started to Mozarabe from Almeria in late August 2018. It was hot sometimes reaching 100 degrees F. I used an umbrella and tried to start very early in the morning. Make sure you have enough water as well as some food, especially on Sundays since most bar/cafes/stores were closed in smaller towns.
Took me nine days--about 22km/day-- to reach Granada a day longer than planned since I was stopping early to get out of the heat. Folks along the way were helpful, even with my minimal Spanish.
There is a 30 km jog over hills/mountains without any pueblosto to reach Quéntar so make sure you have enough food/water.
In mid-September I had rain a number of days, but was past Granada. An umbrella works fine to keep rain off head and pack. If you use hiking poles, likd I did, figure out a way to attahch to your pack so you could your poles most of the time.
Enjoy