Horses naturally feel more energetic as the weather gets cooler, so you need to be prepared for any unruly behavior. First, be careful when you’re turning your horse out, for a frisky animal will sometimes spin around quickly and let out a buck as it runs into the field. You can be kicked as this happens if you aren’t able to move away fast enough. Instead of walking into the paddock or field with your horse, closing the gate, then releasing the animal, it would be wise to turn your horse around to face the gate, then wedge yourself in the small gap of a nearly-closed gate and release the horse from this safer spot.
As for the bucking, which is commonplace, and rearing, which is not, it’s important to know ahead of time how to deal with these issues. For bucking, the correction is to keep the horse’s head up and drive it forward with your legs. A horse can only buck you off if it’s able to get its head low enough and rear end high enough that the saddle can serve as a launching pad.
Conversely, you want to keep the horse’s head low when you’re dealing with a horse that wants to rear. It’s important to have very quick reactions to a rear in the making, for the higher the horse lifts its front feet off the ground, the more the rider is going to slide backward in the saddle. (Worse case scenario is if the rider’s sliding weight pulls the horse backward, where it falls onto the rider.) If the horse starts to lift its head and front feet, lean forward and hold one rein down toward the point of the horse’s shoulder, while holding the mane with the other hand. Drive the horse forward adamantly with your legs, for the more forward motion you have, the harder it is for the horse to rear.
If you’re having lots of trouble with bucking and rearing, longe the animal before you ride to take the edge off a little. (There are detailed instructions for longeing in Chapters 2 and 6 of my book, The Complete Guide to Hunter Seat Training, Showing, and Judging.)