The central west region has a temperate climate with warm to very hot summers and no dry season. Being inland there is a marked seasonal and diurnal variation in temperatures. You should check ahead when planning a trip. On some days the temperature can move through 20 degrees centigrade, and in recent years temperature can get above 40 degrees in the summer months and down to minus 5 degrees in the winter.
Rain is mainly in storms or squalls that pass through. Set-in rain for a few days is rare.
Best months for cycling are probably the spring months of September and October, and then autumn months of March through to June, although frosts can happen in May and June. Given the warm season temperatures carrying sufficient water is vital. Know your requirements.