Westerstraat is een straat te Winsum in de gemeente Winsum en is gelegen in de Nederlandse provincie Groningen.
| Postcode | Huisnummers |
|---|---|
| 9951 EM | 1, 3, 5, 7, 9, 15, 17, 19, 21, 25, 27, 31, 33, 35, 37A, 37B, 37, 39, 43, 45, 49; |
| 9951 EN | 2, 4, 6, 12, 14, 16A, 16, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44; |