Updated: 2026-09-27
The first day that had to stay below freezing was 23 January. The last was 4 March. Between those two dates the air at Malham Tarn never climbed out of frost for 41 consecutive days — the longest frost run ever recorded at the station in more than half a century of daily records.
Longest run of consecutive frost days, 23 January – 4 March 1986
That single run of 41 days can be matched but never beaten in the Met Office MIDAS record for this station. The nearest equal contender is a winter seven years earlier: from 17 January to 26 February 1979 the ground at Malham Tarn also froze without a break, again for 41 days. Two different winters, two runs of the same remarkable length — an unusual piece of symmetry in a mountain-edge climate where most frost spells break up long before the fortieth day.
The data analysed here is the daily record held for Malham Tarn in the Met Office MIDAS archive, the UK's national weather station dataset maintained under the Open Government Licence. For this page the full annual perspective covers the complete years from 1959 to 2015, so every run quoted below is measured against that same period.
Frost spells at this station cluster in the deep winter months, and the all-time list is dominated by two particularly hard winters. Each row below is a single continuous run in which no day ever rose above freezing.
| Run start | Run end | Consecutive frost days |
|---|---|---|
| 23 January 1986 | 4 March 1986 | 41 |
| 17 January 1979 | 26 February 1979 | 41 |
| 25 December 1984 | 29 January 1985 | 36 |
| 22 December 1962 | 26 January 1963 | 36 |
| 29 January 1963 | 4 March 1963 | 35 |
The winter of 1962–63 appears twice in that short list, and its second entry is the striking one: the frost broke briefly in late January 1963 and then locked the ground back up again for a further 35 days, running from 29 January to 4 March. A winter that already produced one run of 36 days followed it with a run of 35.
What makes the 1986 and 1979 runs stand out further is their timing. A frost sequence beginning in mid-to-late January has more of the winter still ahead of it than one beginning in December, yet both stretched on into early March — the 1986 run holding right through February and only releasing on 4 March. At an upland site sitting at 381 metres above sea level, this is the kind of sustained cold that shapes how late the season can still bite.
The table below shows the longest unbroken frost run recorded at Malham Tarn in each complete year of the record. Read it as a winter-by-winter thermometer: some years never managed more than a handful of consecutive frozen days, while the great winters pushed past a full month.
The chart shows the complete annual series. The table lists the most notable years; the full series comes from Met Office.
| Year | Longest consecutive frost run (days) |
|---|---|
| 1963 | 35 |
| 1969 | 32 |
| 1979 | 41 |
| 1985 | 29 |
| 1986 | 41 |
| 1991 | 30 |
| 1998 | 5 |
Across the complete years from 1959 to 2015 the longest frost runs swing widely. The smallest belongs to 1998, when the longest unbroken frost stretch lasted just 5 days. Three years sit at 6 days — 1989, 2002, 2007 and 2011 among them — showing how quickly a mild winter can cut a frost spell short at this station. At the other end, the four decades spanning the early 1960s to the late 1980s carry the headline figures: 41 days in 1979 and again in 1986, 36 days in the winter shared between 1984 and 1985, and 35 days in 1963.
After the late 1980s the longest runs shrink. The strongest single-year value in the most recent stretch of complete records is 26 days in 2013, followed by 17 days in 2009 and 17 days again in 2010. It is a quieter, choppier picture of winter than the sustained freezes seen in 1963, 1979 and 1986 — but the frost season itself has not disappeared, as any run of 16 days in 2015 confirms.
Two numbers frame everything on this page. The longest run of consecutive frost days ever recorded at Malham Tarn is 41, achieved on two separate occasions — 23 January to 4 March 1986 and 17 January to 26 February 1979. On any given day across the complete annual series from 1959 to 2015, a frost run at this station could last anywhere from a handful of days to more than a month, depending on the winter.
Source: Met Office MIDAS daily station data, station Malham Tarn, complete period 1959–2015.
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