The Mediterranean-type climate of the Avon River Basin is typified by mild wet winters and hot dry summers controlled primarily by 'southern oscillation of the of the anticyclonic belt' with relatively small influence of the 'El Nino' effect. There is some cyclonic influence during summer months. Annual rainfall decreases from about 700 mm in the west to 325 mm in the east of the basin. Approximately 70% of annual rainfall falls during the 5-month growing period (May-September) and is of relatively low variability. Frosts also occur during this period.

Wet winters or intense rainfall events cause occasional flooding. Major flooding has occurred in 1910, 1917, 1926, 1930, 1945, 1946, 1955, 1958, 1963, 1964, 1983 and 2000. The potential for change in climate may be significant to natural resource management in the Avon River Basin although the extent to which his could occur remains uncertain. Some changes predicted (CSIRO, 2001) by about 2070 (compared with 1990) include:

• higher temperatures (1-5 degrees Celsius warmer)
• changing rainfall trends (seasonality and annual averages)
• higher evaporation rates
• more frequent extreme weather events

The agricultural industry is a substantial contributor of the ‘greenhouse gas’ emissions that are considered to be a cause of climate change.