Cmon Seabreeze!
Youre telling me it's blowing 25-30 knots at Kurnell but under 15 knots just north at Narrabeen?
theres not enough wind to spread a fart
It really is quite normal that the Northern beach's get no wind, while the airport and Kurnell are howling.
Its all about the topography of the area.
Your better off using North Head or Fort Denison as your referance for wind on the northern beaches.