something's happening here

It happens every year like clockwork. As summer arrives in Tucson, with temperatures hovering above 100, second home owners and winter visitors migrate back to their primary residences in cooler climes. And since we have a lot of second home owners and winter visitors, the roads, shops, restaurants and just about everything else in the Tucson Foothills are half-full, or half-empty, or less.
I never think about making a reservation for dinner in the summer at all but the most popular, or reservation required places.
You could walk into most restaurants without a reservation and get seated immediately, and sometimes they were so nearly-empty that you felt like an intruder. I wrote about this at the beginning of summer in 102 in the shade, and in hindsight, I wish I'd waited to write that piece. Because I've been out to dinner at quite a few restaurants since I wrote 102 in the shade, and this year for some reason, it's a whole different story. Every restaurant has been full or nearly full, and often we've had to wait for a table, sometimes as long as 45 minutes. These places have been jammed, with people waiting at the bar for tables and waiting outside in the heat. And I'm talking about week nights, Monday thru Thursday. I can't imagine what happens on the weekend.
I don't get it. And to add to the mystery, a lot of big new restaurants have opened in the Tucson Foothills in the last couple of years, a few of them in just the last few months - Big restaurants with many tables and big bars that seat lots of people. What's going on?
Are more second home owners staying here for the summer, are we suddenly getting an influx of summer visitors, have people given up cooking for the summer, are the new restaurants in the Tucson Foothills attracting a new crowd from all over Tucson, or, are people just eating out a lot more?
If you've found yourself waiting for a table on a Tuesday evening when it's 102, I'd like to hear your theory on what's happening.