The Met Office says 2013 started mild, with maximum temperatures often above 10C, but a cold spell dominated the middle of the month bringing hail, sleet and snow which persisted on the hills.
The mean temperature was just below the long-term average of 6.1C, but would have been significantly lower had it not been for the mild start and end to the month.
The warmest day was January 3, with a maximum of 11.6C and the coldest day, the 15th, saw a minimum air temperature of minus 0.4C and a temperature on the ground of minus 4.1C.
There were two days with air frosts and 10 days with ground frosts.
There were only 45 hours of sunshine last month, 17% below the January mean.
Rainfall at Ronaldsway measured 93.6mm, slightly more than normal for the month, with more than a third of that, 38mm, falling on the 25th, making it the second wettest January day on record.
This, falling on already saturated ground, caused widespread flooding during the evening.
There were three days of hail, four of sleet and four with snow at the airport.