Rail punctuality dipped last month as train companies battled floods and high winds.
A total of 83.7% of trains ran on time in the four-week period from December 8 2013 to January 4 2014, Network Rail (NR) said.
This compared with a figure of 88.3% for the same four-week period in 2012/13.
Worst-performing company in the most recent four-week period was Southern, where many fallen trees, as well as landslips on the Brighton line, meant that the company was only able to run 73.1% of trains on time.
The next worst-performing company in December 2013 was First Capital Connect (75.9% of trains on time) followed by East Coast (76.9%), Southeastern (77.1%) and South West Trains (78.1%).
Best-performing company in December 2013 was London Overground (96.1% of trains on time) followed by c2c (93.6%) and Merseyrail (93.4%).
Delays attributable to NR - including external factors such as fatalities, which made up around 20% of all delays - accounted for 60% of delays nationally during the period.
NR said: " A succession of tumultuous storms tested the rail industry's resilience during a very difficult period.
"During this period, the railway dealt with multiple and sustained extreme weather conditions. Storm-force winds brought down almost 400 trees on to the railway while torrential rain caused almost 130 floods and 29 landslips, some blocking major routes.
"Thousands of railway staff responded with dedication and professionalism to repair the damage caused."
NR added that "despite these considerable challenges" it had, over the same period, successfully delivered a £110 million investment programme of improvement work involving many engineering projects - the largest ever undertaken over a two-week period.
A spokeswoman for rail industry body the Rail Delivery Group said: "Although four out of five trains arrived as planned over the last month, we know that severe weather disrupted many passengers' journeys and we apologise to anyone who was affected."
"Throughout the recent bad weather and over Christmas thousands of rail staff were out working to remove hundreds of trees that had fallen onto the railway, repair damage to overhead wires and provide information to passengers to help them get to where they wanted to go.
"During periods of severe weather our main focus is to ensure the safety of passengers and staff, but the industry remains committed to investing in improving performance so that passengers see fewer delays and are kept well informed."
The NR figures refer to the public performance measure (PPM) on which NR is judged by rail regulators. Under this PPM, a local train is deemed to be on time as long as it is less than five minutes late, while a long-distance train is on time if it arrives within 10 minutes of the scheduled time.
NR also publishes "real" punctuality figures, known as "right-time" figures. With this measure a train is deemed late if it arrives more than 59 seconds behind schedule.
On this right-time measure, 57.6% of trains were on time in December 2013, with the figure for long-distance trains being only 43.7% and the London and south east England services' figure being 55.9%.
For the 12 months ending January 4 2014, a total of 66.6% of trains national ran on time under the 59-second rule, with the long-distance train figure being only 51.7%.
CrossCountry (43.8%), Virgin Trains (48.9%) and East Coast (52.8%) were the worst-performing companies under this right-time measure for the 12 months ending January 4 2014, while the best-performing companies were Chiltern (86.6%) Arriva Trains Wales (85.0%) and London Overground (84.2%).