Here are some towns in the Western Australian Wheatbelt ordered roughly from highest to lowest average annual rainfall:
1 Gingin (31.35S,115.9E,~600 - 700+ mm): Located in the wettest, western edge of the wheatbelt.
2 Moora (30.65S,116E,~400 - 500 mm): Situated in the northern/central wheatbelt.
3 Northam (31.65S,116.7E,~400 - 450 mm): A major central town, often used as a benchmark for the region's climate.
4 Narrogin (32.9S,117.2E,~450 mm): Located in the southern wheatbelt, which generally experiences reliable winter rainfall.
5 Wagin (33.3S,117.3E,~400 - 450 mm): Located in the southern agricultural zone.
6 Katanning (33.7S, 117.6E,~400 - 450 mm): Southern wheatbelt region.
7 Corrigin (32.3S, 117.9,~350 mm): Central wheatbelt.
8 Merredin (32.1S,118.4E,~300 - 350 mm): Located in the eastern wheatbelt, which is hotter and drier, with a significant decrease in rainfall compared to the west.
9 Southern Cross (31.2S, 119.3E,~300 mm): Represents the drier, eastern edge of the wheatbelt.
NITROGENOUS FERTILISERS FOR CEREAL PRODUCTION
By M. G. Mason (1967)
gives 3 regions based on winter rainfall
A (dry) Mullewa, Morawa, Dalwallinu, BonnieRock, Bencubbin, Wyalkatchem, SouthernCross, Merriden, Hyden, SalmonGums
B (mid) Geraldton, Dongara, Moora, WonganHills, Northam, Cunderdin, Corrigin, LakeGrace, Newdegate, Ravensthorpe
C (wet) Beverley,Brookton, Boddington/Dwarda, Narrogin, Wagin, Dumbleyung, Pingrup, Katanning, BoyupBrook, Kojonup, Cranbrook, Jerramungup, Esperance
Evaporation matters (as does evapotranspiration)
Based on data regarding ANNUAL pan evaporation, which represents potential evapotranspiration (water loss from the soil and plants), the main towns in Western Australia's Wheatbelt generally show a gradient from higher evaporation in the drier, eastern, and northern areas to lower evaporation in the cooler, western, and southern areas.
Here are the main towns in the Wheatbelt, ordered roughly by decreasing order of annual potential evapotranspiration (highest to lowest, based on regional climatic trends):
1 Southern Cross (~2428 mm annual pan evaporation)
2 Corrigin (~2027 mm annual pan evaporation)
3 Merredin (High, similar to central/eastern inland rates)
4 Lake Grace (~1854 mm annual pan evaporation)
5 Beverley (~1936 mm annual pan evaporation \[Dash] note: historically lower than far east, but varies by site)
6 Northam (Lower, in the wetter western part of the wheatbelt)