Heatwaves in New York are different from heatwaves in Phoenix. Phoenix is dry. NYC is the inside of a wet sock. Add asphalt, exhaust, and zero shade, and you get conditions that put guys in the ER if they're wearing the wrong shirt. So when the forecast hits 95+ for three days running, we shift the front of the store.
First thing to come forward: ventilated hi-vis. Carhartt makes a Class 2 mesh-back vest that runs about $35, and we sell more of those between June 15 and August 30 than we sell of every other vest combined the rest of the year. The mesh sounds like a small thing. It is not a small thing. It's the difference between a 6 and an 8.5 on the misery scale.
Cooling neck towels — the cheap evaporative ones — are $8 to $12 and they actually work. Soak them in cold water at the start of the shift, stuff one in your back pocket, swap it on every break. We stock them by the register because guys forget. The Ergodyne Chill-Its hold up best across a season. The $4 ones from gas stations rip in two weeks.
On bottoms, lightweight ripstop is the move. Carhartt's Force Relaxed Fit Ripstop Cargo runs $55 and breathes a generation better than canvas. If a guy is stuck in canvas double-front Carhartts in 95-degree weather, he's fighting the pants all day. The ripstop is 60% lighter and dries fast when he sweats through it.
Boots in heat are tricky. You can't go to a low-cut sneaker on most sites, but you can pick a boot that vents. The Timberland Pro Hyperion at $180 is mesh-paneled and won't bake the foot the way a leather boot does. The Rockrooster Yukon at $135 is a cheaper ventilated option that customers report back on positively.
Don't forget the head. We stock cheap straw cowboy-style sun hats at $15, vented bucket hats at $22, and FR-rated balaclavas for the rare welder who needs to keep face-coverage up in heat (those are miserable, but the alternative is worse). For most crews, a wide-brim bucket and a soaked neck towel is the move.
Gloves in heat: skip the leather palm. Go to a knit-back, nitrile-dipped glove like the Carhartt A540 at $14. Leather palms on a 95-degree day turn into oven mitts.
The last thing I'll say is policy, not gear. We had a customer last August whose foreman wouldn't allow water breaks unscheduled. The guy quit the job on a Friday, came back Monday to buy boots for a new outfit. If your foreman doesn't run a water-and-shade schedule when the index is over 95, you have a worse problem than which shirt to buy.