✅ Bleak describes something that is cold in a piercing way or something that is depressing. These two senses often coincide in descriptions of bleak weather (I stayed inside because it looked so cold and bleak outside; Her prospects were bleak). ✅ Grim describes things that are harsh or unpleasant. Both these senses are also often used when describing people and weather phenomena (I hated camping in the grim weather). ✅ Bleak suggests cold weather, especially weather that involves snow, rain, or wind. Grim suggests unpleasant weather but not necessarily cold weather. ✅ Bleak can also describe hopeless situations (Their prospects were bleak), and grim can also describe things that are stern, sinister, or cruel (He had a grim countenance).