The good news is it sounds like your set up, the bad news is the weather flat out sucks but it can still be done. I have much better luck when the snow is piled high and it is brutually cold out for at least a week. They got to eat and will come in fast. When it is warmer like this I haven't had as much luck.
I have my best results setting up on the edge of grass fields, preferably switch grass. I have also had great luck hunting frozen creek / rivers. They will run them hard at night under a full moon.
Typically I will get in about an hour before it gets dark out. Hang a stand or set up somewhere I can shoot good. I like to put my caller a good 50-75 yards away. I try to set up so that I will intercept the yotes as they try to circle down wind. It is awesome shooting a yote at 30 yards when he is looking at the caller totally unaware that you are standing there with him in the cross hairs.
I don't ever turn the call on until right before the sun goes down over the horizon. I will start out with a woodpecker call or jackrabbit in distress. Woodpecker has killed a lot more dogs though. The first 10 minutes I will play the distress call, the next 10 minutes I will wait, then the last 10 minutes I will do lone howls or challenge calls and then the last 5 I will turn on group howls. Killed quite a few doing it this way.
Full moon nights are a blast as well. Don't overhunt your area. Set up so that you don't spook any walking in. Be prepared to shoot first and always take the first good opportunity at a shot. I've screwed myself letting them get in too close then having them bust. Always shoot the second coyote first. I have had the first coyote run about a 100 yards and stop and look back for perfect shot.
Setting up in the timber works well also. I usually just stand next to a large tree. They are so focused on the call they never notice your there. If you hear them barking, you have been busted and most likely will not get a second chance. Always good to have a buddy watching the back side as well.
Usually if I don't have them within 10 minutes, I most likely will not get one to come in. I messed around with decoys once but had too many owls / hawks go after it.
It also might not be a bad idea to have a shotgun laying over your lap. Sometimes they will be on top of you so fast and coming from behind it is quite the shocker when they run by at 10 yards from behind you.
Shoot them in the shoulders and they are done. Shoot them in the lungs they can go aways. Shoot them in the guts and they will usually spin doughnuts out in the middle of the field. I use a 22-250.
The mornings are good as well but have had better luck right when the sun starts to pop up.
goodluck.
