From the 80s, while the climate changes issue starts to rise interest, due to financial constraints and the advent of satellite era, monitoring networks begin to decline [1]. Remote sensing with its capability of global monitoring put on a side the direct observation that often requires high investments at local level for installation and maintenance. Nevertheless in-situ monitoring is essential for a large number of actions that requires continuous, long-term, high-frequency, and accurate data as well as to calibrate and validate remote sensing data. With the advent of IoT in situ monitoring is getting back the necessary attention and more people, also in the field of FOSS4G, are starting to work in this field. The IstSOS development team is working since the 2009 to bring in-situ monitoring back to the golden ages fostering the interoperability and the data management best practices. Several projects are here presented to demonstrate how istSOS, IoT and openness can contribute to this goal through a number of applications in the fields of agriculture (ENORASIS), water management (hydromMetTI, FREEWAT, TRESA), risk mitigation (SITGAP, MIARIA), health (ALBIS), development and cooperation (4ONSE).