Updated: 2026-09-25
The single most useful number for anyone planting tomatoes outdoors near Glasgow is this: across 95 full years of records, the average last frost at the nearest measuring point falls on day 103 of the year — the average date of the last air frost, which lands in the equivalent of month 3.4, the first days of April.
That is the date to plant against, not a guess. But the same series also shows a last frost as late as 2 April 2010, and as early as 28 March 1914. Those two extremes tell you how much a single cold spring can shift your plans.
Glasgow has no weather station of its own in this archive, so the honest approach is to use the closest one. The nearest measuring point is the Paisley station in Renfrewshire, sitting at an altitude of 32 m and about 11.4 km from Glasgow. Everything below describes what that station recorded — not a precise reading for every street in the city. Glasgow's own climate can differ from Paisley's because of local factors: a different elevation, proximity to the Clyde, the shelter of a valley, or distance from the coast all move the last frost by days. Treat these figures as the best available reference, measured where it was actually measured.
Tomatoes are killed by frost. The date that matters is therefore the last morning on which the air temperature at ground level dropped to freezing or below. The Met Office archive for Paisley covers the years 1914 to 2010, and across those 95 full years the average last frost came on day 103 of the year — the equivalent of month 3.4, which puts it in the opening days of April.
That average is the anchor. Plant your tomatoes outdoors before it and you are gambling against the tail end of the frost season. Wait until after it and, on average, you are clear. The spread around that average is what actually costs gardeners their crop, and the two extreme dates show how wide it can be: the earliest last frost in the series came on 28 March 1914, the latest on 2 April 2010.
The monthly figures explain the shape of the season. Each row below shows the average overnight minimum, the coldest minimum ever recorded in that month, and the number of days of data behind it, drawn from the Met Office record for the Paisley station.
| Month | Average minimum (°C) | Coldest minimum (°C) | Mildest minimum (°C) | Days of data |
|---|---|---|---|---|
| January | 1.6 | -14.8 | 11.3 | 2944 |
| February | 1.6 | -10.0 | 11.0 | 2684 |
| March | 2.7 | -10.0 | 10.6 | 2944 |
| April | 4.4 | -4.4 | 12.2 | 2850 |
| May | 7.0 | -1.7 | 13.9 | 2945 |
| June | 9.8 | 1.5 | 17.8 | 2850 |
| July | 11.6 | 3.9 | 18.5 | 2945 |
| August | 11.4 | 2.2 | 18.0 | 2945 |
| September | 9.5 | -0.2 | 16.7 | 2850 |
| October | 6.8 | -4.4 | 15.2 | 2945 |
| November | 3.7 | -12.2 | 13.5 | 2848 |
| December | 2.1 | -14.5 | 11.1 | 2945 |
Two months in this table matter most for planting. In April the average overnight minimum is 4.4 °C, and the coldest April night in the whole record fell to -4.4 °C — a killing frost. By May the average minimum has risen to 7.0 °C, and the coldest May night on record still dipped to -1.7 °C. That single May figure is the quiet warning in this data: even in the month most gardeners consider safe, Paisley has logged a night below freezing.
An average is not a promise. The April average minimum of 4.4 °C sits comfortably above freezing, yet the record low for the same month is -4.4 °C. In practical terms, a warm April average can still contain one sharp frost, and it is that one morning that ruins unprotected tomato plants. This is why the average last frost date — day 103 — is framed as the point after which, on average, the frost season is over, rather than a night-by-night guarantee.
May's average minimum of 7.0 °C looks reassuring, and for most of the month it is. But the coldest May minimum ever recorded at the station is -1.7 °C. A late, freak cold snap in May is rare, but it is in the record. Gardeners working from this data tend to keep fleece or cloches within reach until the end of May for exactly this reason.
The table below does not list every year of the period. It isolates only the two extremes of the Paisley series: the earliest last frost and the latest last frost recorded across the full period 1914 to 2010.
| Year | Last frost date |
|---|---|
| 1914 | 28 March |
| 2010 | 2 April |
For a tomato grower near Glasgow, the data points to a simple plan. Use day 103 — the start of April — as the average last frost. In most years, that is when the frost risk at the Paisley measuring point fades. But the record shows last frosts out to 2 April 2010, and even a May night below freezing after the season should have turned. The safe move is to plant after the average date and keep protection handy for the first couple of weeks, especially if the spring has been slow to warm.
The honest caveat remains: this is Paisley's record, not Glasgow's own. A garden on higher ground, a plot closer to the Clyde, or a spot tucked into a sheltered valley may see its last frost arrive earlier or later than the station's average. The figures here are the most reliable guide available, measured exactly where the Met Office measured them.
Source: Met Office — Paisley station, Renfrewshire (MIDAS archive). Reference period: 1914–2010.
HistoClima Tools: discover the weather on the day you were born, your wedding day, or your birthday-week statistics.
AI-assisted content from official Met Office data, automatically verified. 🤖 IA-assisted content · Art. 50 EU AI Act
© 2026 HistoClima · data: Met Office (OGL v3.0) · not affiliated with Met Office · citation permitted with source.