Updated: 2026-09-26
If you want a single answer to when it stops being risky to put tomato plants outside in Leeds, the official Met Office record for the city's weather centre gives it to you: the last spring date on which the ground still froze was 21 April 2001. That is the latest recorded air frost (a minimum temperature at or below 0 °C) recorded in April, May or June at the Leeds station across the 1986–2002 record. It is the marker gardeners use to decide the outdoor planting window: anything set out before that date in an unlucky year can still meet a frost.
21 April 2001 is the date to remember.
21 April 2001 — the latest recorded spring frost at the Leeds weather centre
A minimum temperature of 0 °C or below was still being measured that late in April. For anyone with tomato seedlings hardening off on a windowsill or in a greenhouse, that single date is the line not to cross in a cold year.
Tomatoes are tender plants. They stop growing, and the leaves blacken, once the air around them drops to freezing. The Leeds record shows the local frost season does not simply end with March. It can reach into the second half of April, which is why the safe date is not the first warm day of spring but the point after the latest freeze on record.
April's nightly lows at this station tell the same story. The average overnight minimum for April across the period was 5.0 °C, comfortable for an established plant but not a guarantee. The coldest April night recorded was −2.1 °C, and the mildest April night reached 14.0 °C. Those two numbers sit either side of the danger zone, which is exactly why an April planting is a gamble in Leeds. There is no frost risk written into the May figures: the lowest May minimum recorded was 0.3 °C, still above freezing. June, July and August never recorded a value at or below 0 °C at all.
The table below shows, for each month, the average overnight minimum, the coldest night recorded and the warmest night recorded across the full record. The frost season is visible where the coldest night recorded drops to 0 °C or below.
| Month | Average min (°C) | Coldest night (°C) | Warmest night (°C) | Days observed |
|---|---|---|---|---|
| January | 2.4 | −8.1 | 10.6 | 527 |
| February | 2.6 | −8.5 | 12.2 | 480 |
| March | 3.9 | −6.6 | 11.4 | 527 |
| April | 5.0 | −2.1 | 14.0 | 510 |
| May | 7.9 | 0.3 | 15.0 | 527 |
| June | 10.6 | 2.5 | 18.0 | 510 |
| July | 12.9 | 6.4 | 19.6 | 527 |
| August | 12.7 | 5.5 | 19.4 | 527 |
| September | 10.3 | 2.1 | 16.6 | 510 |
| October | 7.6 | −3.9 | 15.1 | 527 |
| November | 4.9 | −5.5 | 14.1 | 510 |
| December | 3.0 | −7.9 | 13.0 | 527 |
January and February are the deep cold of the Leeds year. The coldest night recorded in the whole record came in February, at −8.5 °C, with January not far behind at −8.1 °C. March still drops to −6.6 °C, which is why an early March planting outside is out of the question. April softens to −2.1 °C as its coldest night, but that single figure is what makes late planting risky: a night cold enough to freeze can still arrive.
May is the first month in which the coldest night recorded stayed above freezing, at 0.3 °C. From June onwards the pattern is safe — the coldest June night recorded was 2.5 °C, and the coldest nights in July and August were 6.4 °C and 5.5 °C respectively. Any outdoor tomato planting that survives the last April frost will not see a freezing night for the rest of the growing season based on this record.
Autumn creeps back in gently. September's coldest night recorded was 2.1 °C, still above freezing, but October falls to −3.9 °C and November to −5.5 °C. Those figures matter if you are trying to keep tomatoes cropping into autumn: the first real cold push usually arrives in October at this station.
Treat 21 April as the date the record says it is safe to move tomatoes outdoors at the Leeds weather centre. Before that, a frost is possible in some years. If you want a margin for a cold spring, wait until early May, when the coldest night recorded across the whole period was 0.3 °C and the average overnight minimum sits at 7.9 °C. After May, frost is simply not part of the Leeds growing season in this record.
Source: Met Office MIDAS archive, Leeds weather centre (station 00523) — period 1986–2002. Open Government Licence (OGL v3.0).
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