Change in atlanta
 

I plan to fly on delta to atl then change planes on dl to ams. Is 2 hr layover, in august, enough time?

Not clear on what the month has to do with it, but you should be fine. If it's on one ticket and you miss your connection, you'll be accommodated on another flight to get you to AMS. You question is pretty content-sparse, so there's no way of knowing if there are any later services, but I'd not fret right now.

I think 2 hours should be enough time.

For more information, see Minimum Connection Transfer Time at Atlanta (ATL): The Definitive Thread in the Delta forum.

I mentioned august because my experience in Atlanta has been awful in April - May. Only a few times there, but totally consistent with delays due to fog every time I flew there. And it's been at least 10 yrs since I flew there.

The flight I'll take to AMS is the last flight of the evening. Biz class.

Thanks for that link.

Even if you misconnect - which is unlikely - the last flight to AMS is not the last flight to Europe. DL has ATL-CDG at 11:59pm; easy connections between CDG and AMS by both air and rail.

Change in atlanta
 

Whether you're likely to make the connection has less to do with the weather in Atlanta than the weather wherever you're coming from

It's probably more than enough time. If your inbound flight is delayed, there's a good possibility your outbound flight is delayed as well. Thunderstorms are always a weather option in August, but worrying about it won't change anything. And wasting a half day there getting into ATL too early seems like a poor choice to me. Did you look at the on-time %'s for your flights?