This is making me crazy. I've cleaned all PVC, replaced the p trap, cleaned the disposal, checked the vent. But the sewer smell keeps appearing for several summers now, but only in the evenings after a hot summer day. It goes away once the weather cools down. The smell is so strong and definitely sewer. Any ideas? Thanks!

Septic tank or city sewer?

Sorry, it is city sewer... thanks!

You're going to hafta get "down n' dirty" to track this down. Sniff around. Where does it smell the strongest? Under the cabinet floor? The trap or disposal? The drains? Where the stubout comes out of the wall? Someplace has just got to smell worse then others. Let me know, Good luck, Tom

Do you have a disposal and is it properly trapped? This is a likely source of sewer gas.

First, let me thank you both for your quick response. I am so appreciative for any new suggestions. Yes, I do have a disposal and I can only assume it's properly trapped. It is connected just above the "p" trap to the same pipes from the other side of the sink. Does that sound proper?

I got "down and dirty" and the worst of the smell seems to be coming from behind the cabinet wall around the hole this is drilled for the pipes to go wherever they go from there (does that make sense?).

Is sewer gas dangerous to one's health?

If the lateral line inside the wall has a crack or is leaking then that would give you the symptoms you describe.
Sewer gas is harmful to your familys health and the methane content makes it explosive under the right conditions. Good luck, Tom

Thanks again Tom... sounds like it's time for me to call in the professional - I'm not so confident or capable when it comes to cutting into walls. And now I'm a little scared about the "explosion" possibility.