Best time to cruise South America / Antarctica?

looking at a B2B next year on Infinity ..

Assuming winter here in Nth America is ideal there?!

Any suggestions?

As far as I know, passenger cruise ships only cruise South America and Antarctica during their summer (northern hemisphere's winter) and even then Tierra del Fuego and Antarctica will be chilly. Check out http://www.weatherbase.com/search/search.php3?query=Antarctica for average temps in Antarctica and http://www.weatherbase.com/weather/country.php3?r=SOU for average temps in Chile (Punta Arenas) and Argentina (Ushuaia).

Yes - early 2018 and late

Didn't know if ones preferable to the other

We went in December of 2016, there was still snow on peaks in the fjords of southern Chile/Patagonia. The penguins in the Falklands were setting on nests, many chicks had hatched (can you say Too Cute!).

Our weather around Cape Horn was amazingly calm (think farm pond) with higher seas as we sailed north until we entered more fjords on our way to Puerto Montt (Chile).

At the end we took a shuttle to the Santiago airport, flew to Lima and did Machu Picchu on our own. Great trip...wonderful weather, although Machu Picchu was drizzly.

This past winter we did a 31 day cruise from Los Angeles to Rio de Janiero from December 4 to January 5. The temperature in Rio was 111 degrees farenheit!, Montevideo in the 80s, Buenos Aires in the 90s, the Falkland Islands in the upper 40s/low 50s and very windy at Volunteer Point, Ushuaia in the low 50s (and very windy), Punta Arenas also in the low 50s, and Valparaiso was in in the 80s. This was the at the beginning of summer in South America.