Why does your gas hot water heater pilot keep going out on very days only?

Insufficient gas pressure: Check if there is enough gas flowing to the water heater. If the gas pressure is too low, the pilot flame may not be able to stay lit.

Check the thermocouple: The thermocouple is a safety device that shuts off the gas supply to the pilot burner if the pilot flame goes out. If the thermocouple is dirty or damaged, it may not be able to sense the flame properly and may shut off the gas to the pilot.

Drafts or wind: Strong winds or drafts can blow out the pilot flame. Make sure that the water heater is installed in a location that is protected from wind.

Obstructions in the flue: Debris or obstructions in the flue can block the flow of combustion gasses and cause the pilot flame to go out. Make sure that the flue is clear and unobstructed.

Water heater is too old: If your water heater is more than 10 years old, it may be time to replace it. Older water heaters may not be as efficient as newer models and may be more likely to experience problems with the pilot light going out.