This dataset contains a satellite observed timeseries of the extent of irrigated summer crop areas in NSW from present day, back to 1987. Observations have been derived from medium-resolution multi-spectral satellite imagery (30m/pixel Landsat with a 16 day return interval and 10 m/pixel Sentinel-2 with a 5 day return interval). The presence of irrigated crops is derived from the application of the Normalised Difference Vegetation Index (NDVI), which quantifies vegetation density and health based upon the reflectance of red and near-infrared light in multispectral satellite imagery. Expert opinion is then applied to qualify whether a field was irrigated, based on its greenness relative to the surrounding landscape throughout the summer season (December to April). The polygons are delineated in a semi-supervised manner and are accurate to the closest hectare. It should be noted images captured in December may reflect signs of water application representative of irrigated areas, but on account of limited visible greenness from emerging crops may not be included.