Using data from the MODIS (Moderate Resolution Imaging Spectroradiometer) instruments found on the Terra and Aqua satellites, a monthly cloud fraction map of Washington can be generated using the parameters below.

The 1-degree spatial resolution data used to produce the plots is averaged over the selected period and is produced using the primary cloud fraction parameter from cloud mask in the MODIS Level-3 monthly global dataset (Terra, MOD08_M3 and Aqua, MYD08_M3). Each satellite makes 2 passes over the state a day at about 11-12pm and 9-10pm for Terra and 2-3am and 1-2pm for Aqua (PST).

Data for Terra is available beginning February 2000 and for Aqua January 2002. For both satellites, data is available through March 2008.