I lived down there near the Futa on the Rio Azul. From November to Early March. December can be rainy and difficult camping. Jan is very nice as a whole but if you are not ready for big class V than I would suggest early to mid February as the weather gets a whole lot better, i.e. warmer and not nearly as rainy with temps in the low 90's not unheard of. We had a heat wave at the end of Feb. where the temps were over 100 degrees for a week so we booked it over to Bariloche and did an awesome trip on the Manso for 5 day self support. Futa is great big water, although not as much play as you might think. The magic carpet should be in by early Feb. and usually stays around until it starts raining again in March. May I suggest instead of using expediciones Chile that you call on the services of Aren and Sara Rane who happen to have the best access to a play wave, only a mile from the put-in for the Terminator stretch and Aren is the best kayak guide on the Futa. He's got a great camp way sunnier than Spe's camp a real house to cook in and hot showers on demand and a homemade stone hot tub that absoulutely rocks!
If you are interested in the Futa these are the locals to call upon. Aren and Sarah have been down there for 7 seasons and know the area and if the Futa is too big they will find another river to paddle like the Michamuida or the Azul which is in their front yard.
Wish you the best
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