Last Spring Frost Date in London: What the Records Say

Updated: 2026-08-03

If you are planning to plant tender crops or organise an outdoor event in London, the question of when the last frost of spring arrives is crucial. Based on official Met Office data from the St James's Park station (the UK's longest continuous urban weather record), the answer is clear: in most years, the final frost of the season occurs sometime in March or early April. The median last frost date falls around mid-to-late March, but there is considerable year-to-year variation, as the full series below shows.

In a typical season, London's last winter chill arrives well before spring is in full swing. The monthly averages confirm this pattern: January averages 6.2 frost days, February 5.4, March 2.5, and April just 0.4. By May, the average drops to 0.0 — no frost has ever been recorded in May at this station except for that exceptional 1935 event, which stands alone as the latest spring frost in the entire series.

The Coldest Night on Record

While the 1935 frost is notable for its late date, the most extreme cold at St James's Park occurred much earlier in the season. On February 15, 1929, the temperature fell to -10.0°Cabsolute minimum, 1912–2025, the lowest minimum temperature ever recorded at this station. That reading, part of the infamous 1929 winter cold snap, remains the benchmark for extreme cold in central London and has not been beaten in nearly a century.

A Year-by-Year Look: When Was the Last Spring Frost?

The table below shows the last frost date for each year in the series, along with the minimum temperature recorded on that day. A frost is defined here as any day when the minimum temperature falls below 0°C. The series runs from 1912 to 2025, with data missing for some years (1938, 2000–2003, and 2014 are absent from the record).

Some notable years stand out from this series. The winter of 1945 brought the last frost unusually early — on January 29, 1945, with a biting minimum of -6.7°C — meaning London's gardens were effectively frost-free for the rest of that spring. More recently, January 20, 2024 marked the last frost of that season, another early end to the cold spell. At the other extreme, beyond the already mentioned 1935 event, the frost lingered into late April in several years: April 23, 1936, April 21, 1997, and April 18, 1928 all kept gardeners on alert well into the month.

Monthly Pattern: How Frost Days Accumulate

To understand the rhythm of spring frosts, it helps to look at the average number of frost days per month across the entire record. The table below shows the long-term mean for each month at St James's Park. Note that the cold season runs from October through April, with the bulk of frost activity concentrated in the winter months.

The message from these numbers is reassuring for anyone tending a London garden: by mid-April, the risk of frost has effectively passed in almost every year. April averages just 0.4 frost days annually, meaning most Aprils see none at all. May's average of 0.0 confirms that the 1935 event was a true outlier — the only May frost in the entire 1912–2025 record.

Five Late Frost Events Worth Knowing

If you are looking for the absolute latest dates, these are the five most extreme late-spring frosts in the series:

All five of these late frosts were mild — none dropped below -0.8°C — which is typical for a central London spring, where the urban heat island effect softens the worst of the cold. Yet even a slight frost can damage tender shoots, and these dates mark the outer envelope of risk.

In practical terms, if you want to be safe in the vast majority of years, wait until after April 15 before planting frost-sensitive plants. For a 100% success rate based on this 114-year record, you would wait until after May 17 — the latest ever recorded. Most Londoners, of course, take the middle path and plant in late April, accepting the small residual risk that 1935-style event represents.

Context: The Urban Microclimate

St James's Park sits in the heart of central London, surrounded by buildings, pavement, and the park's own water features. This urban environment produces a well-documented microclimate: nights are generally milder than in the surrounding countryside because the city absorbs heat during the day and releases it slowly overnight. As a result, frost dates at St James's Park tend to be earlier than in outer London or the Home Counties. A garden in Richmond or Bromley, for example, can expect its last spring frost several days later than the city centre figures shown here.

The 1929 record of -10.0°C, while extreme for London, is a reminder that even this sheltered location can experience sharp cold when a strong winter anticyclone settles over the British Isles. That reading remains the coldest night ever logged at this station, a distinction it has held for 96 years. For comparison, the last frost dates in recent years have been notably early: 2024's last frost came on January 20, 2025's on February 2, and the previous year's on January 27, 2017 — all far earlier than the historical median.

These shifts are consistent with what climatologists describe as a general trend toward earlier last frosts in southern Britain, though the variability from year to year — as 2021's April 7 frost and 2022's April 3 frost show — remains substantial. The 2010s and 2020s have been relatively mild, but the pattern is far from uniform.

Source: Met Office, St James's Park station (London), period 1912–2025. Data from the MIDAS archive, held at CEDA (Centre for Environmental Data Analysis), Open Government Licence v3.0.

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