Isohyets - Southwest Australia

http://www.dpi.nsw.gov.au/agriculture/field/pastures-and-rangelands/establishment/clover/part-f---choosing-the-right-sub-clover-v

Isohyets are lines that connect areas of equal rainfall amounts.  These values can change over different seasons, years, and even over longer periods.  These rainfall maps can be beneficial to farmers and also with analyzing climate variability.  Specifically, isohyet lines can be used to analyze variation in rainfall amounts between different phases of the ENSO phenomena.

The above image is of Southwestern Australia and and the isohyets are shown in blue.  One notable part of this map is that the rainfall amounts increase as we move toward the coast.  For example, central portions of the region have rainfall amounts of around 250 mm while places along the coast have values well above 1000 mm.