If it's only happening when it's windy, contact a reputable hvac outfit for a shielded vent cap. If it happens occasionaly when it's not windy as well, you might want to replace the thermocouple, about a $12.00 part.

Only happens when very windy and from the east- I will try to get the cap you mention- thank you. Paul

Is the draft diverter on top of the heater installed?

Heater is only 6 mos. old- so, yes it is. Thanks