Seasons · 6 min read
First Frost in London: When Does It Happen?
The first frosty morning is, for a lot of people, the moment autumn stops being gentle and starts being winter. We looked at 35 years of historical weather data for London to find out when that first frost typically arrives, and how much it varies from year to year.
Photo: allen watkin, Wikimedia Commons (CC BY-SA 2.0)
In this article
When does the first frost usually hit London?What actually counts as "frost"?What does 35 years of data show?How much does it vary year to year?How many frosty mornings does each month get?Watching for it yourselfFrequently asked questionsWhen does the first frost usually hit London?
Based on our data for London (1991-2025), the air temperature first drops below 0°C sometime around 14 November in a typical year, measured from the start of September. That's a median, not a promise: in some years the first frost has arrived in mid-October, in others it has held off until just before Christmas.
| Year | Notable first frost | Date |
|---|---|---|
| 1993 | Earliest first frost | 16 October |
| 2020 | Latest first frost (still before year-end) | 25 December |
| 2024 | Most recent year | 20 November |
Source: our own calculation from Open-Meteo historical weather data for London, 1991-2025.
What actually counts as "frost"?
We count a day as the first frost once the air temperature, measured at the standard 1.5 metre height used by weather stations, drops below 0°C. That's different from ground frost, where the temperature right at ground level dips below freezing while the air just above it is still a degree or two warmer. Ground frost typically shows up before air frost does, since the ground radiates heat away faster on a clear, still night than the air above it does. See our glossary entry on frost for more on how this is measured.
What does 35 years of data show?
We used the same ERA5 reanalysis dataset behind our climate archive to find, for every year from 1991 to 2025, the first day between 1 September and 31 December with a minimum temperature below 0°C in London. Every single one of those 35 years had recorded frost by the end of December, so a frost-free autumn is effectively not something London sees.
Splitting the dataset in two gives a result worth noting: the median first-frost date for 1961-1990 and for 1991-2025 both land on the same date, 14 November. Unlike some seasonal markers that have shifted later as the climate has warmed, the timing of London's first frost hasn't moved much across these two 30-plus year periods in our data.
How much does it vary year to year?
Quite a lot. The earliest first frost in our 35-year dataset was 16 October 1993. The latest still within the same calendar year was 25 December 2020, a frosty Christmas Day. Most years land somewhere in between: the first frost showed up in October in only a handful of years, with November by far the most common month, and December as the next most likely.
How many frosty mornings does each month get?
October barely counts as frost season in London, averaging just 0.3 frost days a year. November picks up to about 3.1 days, and December jumps to 7.7. The frostiest months are actually January (9.3 days on average) and February (8.5 days), before tailing off to 4.7 days in March.
| Month | Avg. frost days |
|---|---|
| October | 0.3 |
| November | 3.1 |
| December | 7.7 |
| January | 9.3 |
| February | 8.5 |
| March | 4.7 |
Source: our own calculation from Open-Meteo historical weather data for London, 1991-2025.
So the first frost of the year tends to land well before the frostiest stretch of the winter actually begins: London's coldest mornings, on average, come in the new year, not in autumn.
Watching for it yourself
A 35-year average tells you roughly what to expect, not what will happen this specific year. The most useful number to watch as autumn goes on is the overnight low, not the daytime high, since that's what determines whether a clear, calm night tips below freezing. Check the weather in London or the 14-day forecast as the date approaches, and see our guide on how accurate a 14-day forecast really is for how much to trust it.
Frequently asked questions
When does London usually get its first frost?
Based on 35 years of data (1991-2025), the median first-frost date is 14 November. It has arrived as early as 16 October and, in one year, as late as 25 December.
Does London always get frost before the new year?
In our 35-year dataset, every single year recorded at least one frost between September and December, so a frost-free autumn is unusual for London.
What is the difference between frost and ground frost?
Frost is measured at the standard 1.5 metre height weather stations use. Ground frost is colder air right at ground level, which often arrives before air temperature at 1.5 metres drops below freezing, since the ground cools faster on a clear, calm night.
Which month has the most frost in London?
January, with an average of 9.3 frost days, followed closely by February at 8.5. The first frost of autumn usually falls in November, well before the frostiest stretch of winter.
Check the weather in London or search another place on the locations page.