Yards have micro climates. Like I know that in my yard my agapanthus blooms about ffour or five weeks after my neighbor's. If it has done this beofre you may just need to be patient. You can tell if the tree is dead if you scratch the bark and the layer underneath is anything but green. If it is not green check another place on the trunk in the same way. No green? Bend a twig-did it snap off or does it fx, but not break. No green cambium layer ususally means the limb or tree is dead. If twigs or branches break off with a snap they are dead. When they bend there is still moisture in the plant and a possibility of life. Water in your regular manner and just be patient.