old flu boiler pilot light keeps going off why is this?

i have a bolier its been there 20 odd years, its normally works fine, the olny thing i have to change on it is the copper wire for thr pilot light, since last week the light keeps going of every half an hour or so some time after an hour, is this to do eith the bad weather when i light it there seems to be a lot of wind coming out of the boiler.thank you