Data collected at the Radcliffe Observatory recorded 185.3mm of rain.
Not only was that the highest monthly total observed on the site since 1875, it was also the fourth wettest of all months since records began in 1767.
The Radcliffe Meteorological Station holds the longest, continuous, single-site precipitation data-set in the UK.
its rain gauge is positioned in a pen close to the majestic neoclassical observatory building in the gardens of Green Templeton College. And even in this age of automation, the instrument is still read by eye every morning.
Currently, this task falls to Keble College doctoral student David Crowhurst.
"We had an intense start to the month which was driven by Storm Alex, which saw 60mm falling on one day, the 3rd. That was quite something," he told BBC News.
"But we also had 27 rainy days in the month. A rainy day is when rainfall is equal to or greater than 0.2mm per day, and those 27 rainy days are a record for an October."
It rained pretty much everywhere on 3 October - not just in Oxford. The UK Met Office says that Saturday was the single wettest day for the country as a whole since daily record keeping began nationally in 1891.
Unsurprisingly with so much rain, the Radcliffe station recorded only 70.7 hours of sunshine through October - an exceptionally low number at over 30 hours below the monthly average.
Interestingly, Oxford's all time wettest October in 1875 was accompanied by extensive flooding in the city. That wasn't repeated last month, despite the less than 4mm difference in rainfall totals.
This may have something to do with the lower moisture content of soils following a relatively dry September. It would have meant the ground being better able to hold on to rainwater. But the absence of flooding on a similar scale almost certainly also reflects today's improved management of watercourses.
The very wet October continues a year of exceptional weather in Oxford, following the sunniest May since records began.
As for the coming months, David Crowhurst is watching closely the developing La Niña phenomenon in the Tropical Pacific.
This is a pattern of altered pressure and winds that leads to cooler sea-surface temperatures off the western coast of the Americas. Although thousands of km away, these conditions can have a profound influence on Britain's weather.
A strong La Niña could see some crisp clear days in the weeks ahead, followed perhaps by some more wet weather by the end of winter.