Thick fog at Cork Airport cleared about half an hour after the deadly plane crash.
Weather summaries for aviation authorities showed visibility on the ground was down to 300m around the time when the plane first tried to land.
Broken cloud cover was down as low as 100ft above ground, official reports said.
According to Meteorological Aviation Reports, known as METARs and recorded every half hour, there was very little wind, five to eight knots, but the fog was lifting slightly.
At 9.30am the METARs stated surface visibility was down to 300m but by 10am it had shifted to 400m. By 10:30am visibility was up as far as 1800m.
Fergal Tierney, a private pilot and contributor to Irish Weather Online, said: "There is no confirmation that the actual crash was weather related, but we can say that conditions were near published minima at the time, and the pilots were having problems landing."
Stephen Davenport, from the UK-based MeteoGroup, said the fog was not extremely dense and the worst conditions were between 7.30am and 10am.
"Cork Airport is susceptible to fog in two ways: a mild and moisture-laden south to south-westerly flow of winds from the Atlantic or cooling of moist air overnight so that it condenses into fog, which is what happened here," he said.
Aviation rules for Cork Airport state that a pilot in a plane of this type, the Fairchild Metroliner turboprop, should abandon landing if there is no visual contact with the runway at between 59 and 69 feet above ground.
The pilot tried to land on runway 17 in what the Irish Aviation Authority described as low visibility but aborted and attempted to touch down on the same landing strip in the opposite direction, only to have to abandon again.
The accident happened on landing on the third attempt.