Welcome to Arizona in July. Exact forecasts are hard to come by as we are in the monsoon season. In general you should plan for the possibility of showers and thunderstorms between noon and 2AM, and following a storm it will cool off, but be more humid.
In Greer AZ (near Mt Baldy) the historical avg low is 50, and the coldest 2 weeks ago was 52. It will be colder as you gain elevation and you should plan to lose about 3 degrees for every 1000 ft in elevation. So the top of Mt Baldy could indeed get down to the 40s at night or right after a storm. If you just look at the TH forecast, be mindful it only applies there, not to higher points along your hike. In some cases, like Mt Baldy, it is better to use the map and click along the trail to get a forecast for mid-way up the Mtn.
Hike Arizona it is full of sharp, pointy, ankle-twisting, HAZmaster crushing
Hike Arizona it is full of sharp, pointy, shin-stabbing, skin-shredding
Hike Arizona it is full of striking, biting, stabbing, venomous