Good thinking! Clouds can definitely impact the diurnal range of temperatures.

And yup, it is possible derive a seasonal anomaly of "cloudiness" from satellite data. Sort of like this Outgoing Longwave Radiation (OLR) anomaly image we often use in the tropics to note where thunderstorm activity is above and below-average.
https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_update/…