We provide continuous bihourly temperature and humidity data (2021-2023) of five caves and two blowholes from an arid and one of the largest contiguous karst areas in the world, the Nullarbor Plain in south Australia. The data were recorded with ten TGP-4500 Tinytag Plus 2 self-contained temperature (resolution ±0.01°C or better with reading range from -25°C to +85°C) and relative humidity (resolution ±3.0% or better with reading range from 0% to 100%) data loggers, and are available in a spreadsheet form. The data have great potential to provide insight into karst underground processes, air mass movements, hydrogeology, speleothems and (palaeo)climate, current climatic changes, and biology. This data is largely a continuation of measurements beginning in 2021 (published in PANGAEA doi:10.1594/PANGAEA.939075), and additionally supplements Lipar & Ferk (2022; doi:10.3390/data7030030).Additional funding: Australian Speleological Federation Karst Conservation Fund (https://www.caves.org.au/conservation/karst-conservation-fund).