The climates of the earth's tropical regions are already towards the upper end of human thermal tolerance. The northern Australian tropical region is a particularly challenging environment for human physical activity and regional development projects. Increases in temperature and rainfall will exacerbate these challenges. Knowledge of past climatic trends and their impacts provides important information for prudent development planning. This paper quantifies the observed changes in temperature and rainfall across northern Australia for the period 1911-2013, based on Australian Bureau of Meteorology (BOM) temperature and rainfall data for 4 coastal and 3 inland locations across the region. We compared two 30 yr periods, 1911-1940 and 1984-2013, to the baseline period 1961-1990 averages and SD values. Trends were identified in decadal monthly temperatures, maximum temperatures > 30 degrees C and minimum temperatures > 21 degrees C, shifts in the daily maximum and minimum temperature frequency distribution curves and changes in seasonal rainfall above and below the +/- 1 SD values. The results indicate this tropical region is now warmer and wetter compared to the 1911-1940 period with an increase in the number of days > 30 and > 33 degrees C. Coastal warming was more pronounced than at inland locations and shows seasonal variations; whilst western and central inland areas have become wetter, little trend change was apparent in the eastern rainfall. With projections of further warming, development plans for the region need to incorporate the associated deleterious impacts on human activity. Such decisions will be critical in determining the success or failure of these projects.