At the conclusion of a three hour bike ride yesterday, I stopped at a friend's house and found at least 5 yellowjacket queens flying around his yard. It's time to put out the traps.
The first decent day since early last fall brought out the yellowjackets. And that makes this is the time to make your neighborhoods more habitable. Except for the queens, the entire yellowjacket colony dies off for the winter. The queens emerge in the spring to start new colonies. When they come out of hibernation they are hungry. Put out traps now and each queen you catch will reduce late summer's yellowjacket population by 5000.
Here's a reminder for how best to get those beasts. Buy a good yellowjacket trap. I like those bile-colored "Rescue" brand traps best.
Use the attractant that comes with the trap and hang the trap in an area where you have a sun/shade boundary - a tree on an outlying branch works well. You can make your trap more appealing by adding a source of free water too. I hang cans cut in half next to my traps.
Your trap won't fill up with yellowjackets because there just aren't many this time of year. But everyone you get will make a big difference for your summer.