Help my 5yr dales x is spooked riding out in the wind what i can do to help him? ?

I have only had him 3 weeks and rode in company and alone on fair weather days in traffic and off road with no problems have bonded well, but have tried to back him in the windy weather as want to ride all weathers to make the most of days off but he really is not a happy boy. have lead him out on hacks too. no access to school only field or hacking. he is green as not worked on much since June. he does need bring back slowly. he has bolted when on the lunge he doesn't like whips or high vis exercise sheet flapping have run it all over body and legs to sensitize him otherwise he is a good boy and a comfy pleasurable ride for an old bird like me!