The best time to visit Grellingen is during the late spring, from May to June, or in the early autumn, from September to October, when the weather is pleasant and ideal for outdoor activities.During late spring, the temperatures are mild, and the natural landscape around Grellingen, including the nearby Jura Mountains, is lush and green. This is an excellent time for travelers who enjoy hiking, cycling, and exploring the region's scenic trails, such as those leading to the Angenstein Castle ruins. The days are long, offering ample time to discover the area's beauty.Early autumn also offers comfortable temperatures and fewer crowds, making it ideal for a relaxed trip. The foliage begins to change, providing beautiful scenery for walks along the Birs River or excursions into the surrounding countryside.