Usually, the nouns of the following categories are masculine words:
male humans and animals: der Mann (man), König (king), Vater (fater), Löwe (lion), Bär (bear)
days, months, seasons of the year, points of the compass: der Sonntag (Sunday), März (March), Herbst (autumn), Osten (East) Exceptions:das Jahr (year), die Woche (week)
forms of precipitation, kinds of wind: der Regen (rain), Schnee (snow), Hagel (hail), Föhn (föhn), Monsun (monsoon), Orkan (hurricane)
five words ending in : der Kaffee (coffee), Klee (clover), Schnee (snow), Tee (tea), See (lake) (also the other form die See (sea))
most nouns that are derived from strong verbs but have no suffix: der Kauf (purchase), Wurf (throw), Sprung (jump), Riss (rip), Gang (gait), but exception: das Schloss (lock, castle)
most nouns ending with , , suffixes: der Lehrer (teacher), Wecker (alarm clock), Fremdling (stranger), Feigling (coward), Schlüssel (key), but exceptions: die Trommel (drum), die Butter (butter), das Fenster (windows), die Schwester (sister), die Mutter (mother), das Wetter (weather), das Zimmer (room)
most nouns ending with : der Boden (floor, ground, soil), Regen (rain), Wagen (car, wagon)