CAPT OF AN ATR42-500 LANDED WHEN THE CURRENT OFFICIAL WX RPT INDICATED THE ARPT WAS BELOW THE OPERATOR'S APPROVED WX MINIMUMS.

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FO WAS PF. LEAVING IAH FOR THE APPROX 23 MIN FLT TO BPT; WE KNEW THERE WAS FOG AT BPT AND WE MIGHT NEED TO RETURN TO IAH (OUR ALTERNATE AS WELL AS DEP). AT THE TIME OF DEP; THE LATEST RPTED VISIBILITY WAS 3/4 MI AND 9 MI VISIBILITY. ENRTE I CALLED MONTGOMERY RADIO FOR CURRENT WX (AUTOMATED) AS TWR CLOSED AT XA00. ALTHOUGH WE WERE ABLE TO SEE THE ENTIRE AREA INCLUDING RWY FROM APPROX 95 MI OUT; ASOS WAS RPTING 1/4 MI VISIBILITY. WE ELECTED TO ENTER A HOLD OVER THE BPT VOR ON THE FIELD WHILE I CALLED OUR OPS TO TELL THEM WE WOULD RETURN TO IAH IF WE COULDN'T GET AN UPDATED AND IMPROVED WX OBSERVATION. LCL OPS ACKNOWLEDGED AND SAID THEY WOULD NOTIFY DISPATCH. SHORTLY AFTER THAT; BPT OPS CALLED BACK AND SAID THEY HAD 'CALLED' AND WERE TOLD CURRENT RVR FOR RWY 12 WAS '3000 FT AND WE ONLY NEED 2400 FT TO LAND.' IT WAS TRUE THAT 2400 FT RVR IS THE MINIMUM FOR THE ILS APCH. I TOLD ZHU THAT WE RECEIVED CURRENT RVR OF 3000 FT AND REQUESTED APCH CLRNC. WE WERE CLRED; FLEW THE APCH AND LANDED UNEVENTFULLY. AFTER ARRIVING AT THE HOTEL AND REVIEWING THE EVENTS OF THE FLT; I BEGAN TO WONDER ABOUT THE ACCEPTABILITY OF ACCEPTING THE WX GIVEN TO US BY OPS. I ASSUME THEY HAD CALLED SOMEONE FROM THE TWR TO OBTAIN THE RVR; BUT IN RETROSPECT WONDER IF THEY WOULD HAVE BEEN THERE SO LONG AFTER CLOSING TIME (APPROX 30 MINS). I DON'T DOUBT THEY (OPS) GOT IT FROM SOMEONE; BUT AM NOT SURE NOW IF IT WAS A TECHNICALLY LEGAL RPT UPON WHICH TO JUSTIFY BEGINNING THE APCH. THIS EXPERIENCE POINTS OUT THE INCREASED DIFFICULTY AND CHANCE OF ERROR WHEN OPERATING INTO AN ARPT AFTER TWR CLOSES. ACR HAD BEEN HOLDING AND IN FACT DIVERTED JUST BEFORE WE BEGAN THE APCH. WE VERY NEARLY DID THE SAME AND POSSIBLY SHOULD HAVE. I INTEND TO DISCUSS THE ISSUE WITH MY CHIEF PLT. MY FO AND I HAVE DISCUSSED THE WX ISSUE AS WELL AS OUR PERFORMANCE AND PREPARATION. WE BOTH AGREE WE LEARNED A LOT FROM THE EXPERIENCE.