Statistics of photometric nights at Paranal (black) and La Silla (red) since UT1 first light, including downtime for humidity. Data is extracted from the telescope observing logs when available, otherwise from the DIMM photometric database (Feb99-Jun99). The dashed lines give the respective long term (1983-2000) sites characteristics (Paranal: 78%, LaSilla: 60%). The impact of the January/February Bolivian Winter was fairly stronger from 1999 to 2001 at Paranal.