The royal Dutch weather and space association, located in “het Gooi”, the area where I live. They arrange free stargazing and sun watching events every month. You can find me there almost every time they arrange something, sometimes even with my own telescope!
“Nederlandse vereniging voor ruimtevaart” or Dutch Space Society. They organize events, lectures, etc. You can get a membership for free if you’re a student, but a lot of their events are for general public too.
The national oceanic and atmospheric administration has two amazing and simple websites to monitor Kp index (for geomagnetic disturbances and storm levels, predicting aurora activity) & Xray flux (for solar flares and their magnitude).