Summer time temps are coming on strong in the valley, but up here on the mountain it's seasonally sensational! Yesterday's high temp was 68 degrees, with an overnight low of 45. It's currently 61 under mostly clear skies.
Eat and hydrate adequately in the days leading up to your trip. You are going to expend a great deal of energy ascending the mountain, and in these forecasted temps, that means a lot of sweating too. Be sure to carry and consume plenty of water/electrolytes. Starting your hike earlier in the morning will give you more time on the trail to take breaks and get out in front of the rising temperatures.
It's also worth considering which trail you hope to take to and from the lodge. Trails like Bull Head, Alum Cave, and The Boulevard receive a fair amount of southern exposure and/or direct sun, heating up quickly as the day progresses. Rainbow Falls and Trillium Gap sit on the mountain's northern side and are predominantly forested, keeping them slightly cooler than their counterparts. If you haven't done Bull Head Trail since it's reopened from the 2016 fires, understand that several miles of trail are now canopy-less, meaning no protection from a relentless summer sun.