Climate
This place is actually pretty comfortable, unlike our neighbor tropical rainforest. The average temperature is 64 degrees Farenheit. The area is humid in December, the South American summer. At all the other times, it's nice and dry, so you won't have to worry about rain spoiling your day. The only downside of the dryness is the fire, so either do a phone call or cut and run.
Geography
The Pampas is located between the Amazon Rainforest and the Atlantic Ocean. The pampas is sectioned in these Argentinian provinces: Buenos Aires, La Pampa, Santa Fe Entre Rios, and Corbada. They also include Chubut, most of Uruguay, and the southern province of Brazil, Rio Grande do Sul. If you're going around the rainforest or the Andes mountains, this won't be so far out of your way. This place is pretty much flat, so you can go pretty far on foot.