EMB ERJ 170/175 ER/LR
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Weather / Turbulence; Inflight Event / Encounter Fuel Issue
Flight Crew Landed As Precaution
Human Factors; Procedure; Weather
We were dispatched [to] ZZZ without alternate fuel. Forecast for ZZZ was few clouds at 25;000 and more than 6 sm visibility. This forecast did not require an alternate.While on downwind leg; a fog bank rolled in over the airport and the weather dropped below CAT II mins. ZZZ1; normally a good diversion airport was also reporting fog. We estimated such a diversion would have put us with only 1;500 lbs of fuel remaining. Enroute we were given several delay vectors. Running low on fuel and out of options; we decided our safest options was to execute the CAT II even though visibility was below our required minimums of 1;200 RVR.Approach and subsequent landing were uneventful. We landed with approximately 2;900 lbs of fuel remaining.Unforecast weather; ZZZ is notorious for unforecasted fog in the late fall and winter. Anytime with clear skies and close temp dew point like today; I will ask for an alternate even if official forecast does not require.
EMB-145 Captain reported executing a CAT II approach with the visibility below their required minimums.