While the weather at Cabañas San Isidro is often mild and spring-like, keep in mind that it is more than a mile high and in the heart of the humid Ecuadorian forest. Rainy, cold days and nights, as well as warm sunny days at Cabañas San Isidro are equally common. So, one needs to come prepared to make the best of the experience.
In general, the weather at San Isidro Lodge is a lot less predictable than in many other areas in Ecuador. The weather has relatively wet periods during the 'dry' season (September-January), as well as dry periods during the 'wet' season (February-August).
The currency in Ecuador is the US dollar (so no need to worry about changing cash if coming from the US). As a general hint for traveling in Ecuador, it is better to bring bill denominations no larger than $20 since larger bills are often not accepted.