we get well over 100 here in cali, i ment low humidity/percipitation is ok especally into the harvest months. plants do not bake if their roots are protected with mulch, about 2 inches is good but you want something that your nutients can get through. liquids do well but solid top dressings have to be aplied under the mulch pulling it back then covering the soil again, its mroe of a problem of the soil drying up and cracking then the plant cannot cool itself or conserves moisture.
one thing about mulch is that most barks are contrast collors to the lush green ganja leaf so a redwood or cedar mulch would make the plants stand out and look better. -ive heard of straw being used and other things like native leaf foliage, if your irrigation lines are placed under the mulch then the mousture will be contained and conserved so that the roots hopfully stay cooler and your plants should thrive. once plants become big and overgrown they shade the soil soo that the sun doesnt bake and dry it out but dry weather can do the same if its windy or not, i mulch and allways sport a bandana so i dont sweat on my plants. i work in the early mornings and avoid the heat of the day, also in the eavinings when its safe to spray plants and the sun is off them for the most part. it gets damb hot some parts of cali and we grow a gang of ganja from the high desarts to all over sothern cal its a issue of constant irrigation and water conservation but if we dont get enough rain well have a drought emergancy and water restictions allready were looking at higher rates for water this season.