  A new observatory site should be investigated for its local climate
conditions to see its potential and limitations. In this respect, we examine
several meteorological parameters at the site of Timau National Observatory,
Indonesia using the ERA5 dataset from 2002 to 2021. Based on this dataset, we
conclude that the surface temperature at Timau is around 18.9 C with a
relatively small temperature variation (1.5 C) over the day. This temperature
stability is expected to give advantages to the observatory. In terms of
humidity and water vapour, Timau is poor for infrared observations as the
median precipitable water vapour exceeds 18 mm, even during the dry season.
However, near-infrared observations are feasible. Even though our cloud cover
analysis confirms the span of the observing season in the region, we find a
significant discrepancy between the clear sky fraction derived from the ERA5
dataset and the one estimated using satellite imagery. Aside from the indicated
bias, our results provide insights and directions for the operation and future
development of the observatory.
