A method for measuring a particles' precipitation rate, said method comprising the steps of: - acquiring at least one first image during a precipitation event through an image acquisition device having a sensor and a lens; and - detecting said particles of said precipitation in said at least one first image by subtracting a background of said first image and setting a brightness threshold (S 1) for detecting said particles, said particles being visible as a plurality of streaks in said image, wherein a first portion of said plurality of streaks comprises blurred streaks, and a second portion of said plurality of streaks comprises focused streaks; characterized in that said method comprises the steps of: - determining from said at least one first image a blurred diameter ( D P,b) and a blurred length ( L P,b) for said plurality of streaks; - estimating an actual diameter ( D P) and an actual length ( L P) for said plurality of streaks by resolving an equations' system having three equations and three unknowns, namely said actual diameter ( D P), said actual length ( L P) and a depth position ( z) of said plurality of streaks, said depth position (z) being the distance of each particle from said lens, in which a first equation has said actual diameter ( D P) as unknown in function of said depth position ( z), a second equation has said actual length ( L P) as unknown in function of said depth position ( z) and a third equation equals the theoretical terminal velocity of said particles to an estimated velocity ( v) of said particles in function of said depth position ( z); - wherein said velocity ( v) of said particles is estimated based on the ratio between a net streak length and an exposure time ( t e) used to take said at least one first image; - estimating said particles' precipitation rate based on said actual diameter ( D P) and said velocity ( v). - acquiring at least one first image during a precipitation event through an image acquisition device having a sensor and a lens; and - detecting said particles of said precipitation in said at least one first image by subtracting a background of said first image and setting a brightness threshold (S 1) for detecting said particles, said particles being visible as a plurality of streaks in said image, wherein a first portion of said plurality of streaks comprises blurred streaks, and a second portion of said plurality of streaks comprises focused streaks; - determining from said at least one first image a blurred diameter ( D P,b) and a blurred length ( L P,b) for said plurality of streaks; - estimating an actual diameter ( D P) and an actual length ( L P) for said plurality of streaks by resolving an equations' system having three equations and three unknowns, namely said actual diameter ( D P), said actual length ( L P) and a depth position ( z) of said plurality of streaks, said depth position (z) being the distance of each particle from said lens, in which a first equation has said actual diameter ( D P) as unknown in function of said depth position ( z), a second equation has said actual length ( L P) as unknown in function of said depth position ( z) and a third equation equals the theoretical terminal velocity of said particles to an estimated velocity ( v) of said particles in function of said depth position ( z); - wherein said velocity ( v) of said particles is estimated based on the ratio between a net streak length and an exposure time ( t e) used to take said at least one first image; - estimating said particles' precipitation rate based on said actual diameter ( D P) and said velocity ( v).