JRC MARS Explorer is a European Commission Joint Research Centre e-service hosted by Wageningen Environmental Research. It provides interactive maps and graphs that help users explore weather conditions, crop development, and vegetation across the European Union and neighbouring countries. Its information draws on meteorological station observations, crop-growth simulations from the MARS Crop Yield Forecasting System, and remote sensing data.

Weather tools present indicators such as temperature, rainfall, and climatic water balance, with maps updated three times monthly and graphs refreshed every five days. Crop monitoring covers winter wheat, spring barley, grain maize, sunflower, potato, rye, sugar beet, and oilseed rape, with maps and graphs updated every ten days. Remote sensing tools show green biomass conditions across arable land and pasture, also refreshed every ten days. Fruit tree monitoring focuses on apple-growing areas, including frost risk around flowering, and is updated monthly.

Users can explore data at European, country, or eligible sub-country levels, and download and reuse displayed maps and graphs when preserving their original format and acknowledging the source.