Weather from Sunday to the present (4)
I believe the answer is:
snow
'weather' is the definition.
(I know that snow is a type of downfall)
'sunday to the present' is the wordplay.
'sunday' becomes 's'.
'to the present' becomes 'now' (both can mean the current period).
's'+'now'='SNOW'
'from' acts as a link.
(Other definitions for snow that I've seen before include "that may come at Christmas" , "White specks on screen resulting from interference" , "White Christmas requirement" , "Cocaine (slang)" , "Wintry precipitation" .)