I'm in inland Ventura County and the hot spells this summer have been rough, but I managed to keep the girls comfortable under a tree when it hits 95+.
One handy feature on the cheap loupes I bought is a little LED light for each lens. When your face is buried in a cola you're blocking the light you need to see it and that LED helps. The other thing is I have crappy old man eyes and thankfully the way these things work you don't need glasses to see, it comes into focus based on your eye's lens and playing with the distance.
Although you might be seeing amber, remember to check sites throughout the plant and give it an "overall" trichome assessment. Seeing amber is a good sign but if it's still 50% clear throughout the plant, you might want to wait. I'm in this boat right now. I have about 5% amber showing on top colas, but still a lot of clear on the mid branches, so I'll be watching the mid branches closely over the next week and a half and see how Milky I can get them, but if I start seeing too much amber on top I'll call it a day and flush. This is why there's never an exact moment, it's an individual judgment call.