Can the smell of gas come and go?

Yes, the characteristic sulfur or rotten egg smell of a gas leak can indeed come and go intermittently under certain conditions. This phenomenon often happens when a very small, hairline crack in a pipe fitting, a partially closed appliance valve, or a flexible connector only leaks gas when the appliance is actively running, under pressure, or undergoing thermal expansion and contraction as temperatures fluctuate throughout the day. Additionally, changing air currents, wind patterns, or HVAC blower cycles inside your home can dilute the gas concentration or push the odor away from your immediate location, making the smell temporarily disappear before pooling again in another room. Because intermittent leaks can quickly worsen and become dangerous, you should never ignore a gas smell even if it fades away. You can verify if a leak exists by having a professional test the lines.