The forest microclimate in a Nothofagus pumilio primary forest (BV) and the effect of a regeneration felling (RG) and an open field (SD) were studied during seven years. Three weather stations measured the global solar radiation (RSG), the air temperature (T_a), the soil temperature at 15 (TS₁₅) and 30 (TS₃₀) cm depth, the relative humidity (HR_a) and the wind speed (V). The results showed that the trends in meteorological variables were similar to those found in forests with similar characteristics. Almost all meteorological variables recorded in BV showed statistical differences, compared to SD, with the exception of T_a, and during the leafless period with T_mina (minimum air temperature) TS₁₅ and TS₃₀. When CR was compared to BV the variables RSG, HR_a, TS₁₅, TS₃₀ (only during leafless period) and V showed significant differences. The higher differences between BV and CR were that in CR the RSG was 4.4 and 3.5 times higher than in BV, for the fully-leaved and the leafless period; and V was 1.2 times higher in CR than in BV. These differences suggest that the microclimate in CR changed respect BV. Because the microclimate and the water balance in the stand affect the vegetation, the differences found between BV and CR are important, and provide a baseline of information to evaluate the effects of the regeneration felling, the most frequently implemented cut in these forests.