The Australian Government Bureau of Meteorology (BOM) provide satellite-derived global solar radiation data. I downloaded 2015 and 2016 data for station number 66120 (Gordon Golf Club). The data are in energy units of megajoules per square meter per day. I multiplied by 2.04 to convert to daily light integral (DLI) units of moles per square meter per day.

This is the DLI in full sun, adjusted for clouds. Any tree or structural shade will result in a lower DLI.

Looking at monthly summaries of DLI, one can see the median and the normal range in each month since January 2015.

I downloaded temperature data from the Sydney Airport (SYD) and used those to calculate an estimated DLI using the Hargreaves equation, as described in Estimating daily light integral in 4 Tennessee cities. I did not make any corrections to the estimate from the Hargreaves equation, and SYD is about 25 km south of Gordon. Still, the uncorrected Hargreaves equation gives a decent estimate of DLI.