Acclimation. I commute most days at work. As the weather shifts you get used to it. The hottest I've ridden in the last few years was around 116F. And yes, it was HOT! OTOH this is a dry heat.
Specific steps to help on any day are
Hydration - Generally the last hour or two at work I sip water constantly. It totals to somewhere between a pint or a quart.
If possible cool off a few minutes before leaving work. If you have a physically challenging job in the heat that may be difficult.
Take it easy. Don't push so hard until you know you can handle it. You'd be surprised how much easier a slightly slower pace can be.