Updated: 2026-07-31
The closest Met Office measuring point to Glasgow is the station at Aberfoyle (Perthshire-in-Central-Region), located at 28 m altitude, about 35.6 km away. Across its full record — from 1968-01-01 to 2001-10-01 — the first day of summer (defined as the first day with a maximum temperature of 25°C or higher) arrived as early as June 11 in 1968 and as late as July 10 in 1997. That is a swing of nearly a full month between the earliest and latest onset of true summer warmth in this part of Scotland.
The most striking fact in the record: in 1968, the first real summer day — a maximum of at least 25°C — came on June 11. That is the earliest first-summer-day in the entire series from Aberfoyle. In contrast, by 1997, residents near Glasgow had to wait until July 10 for that same 25°C threshold — the latest start to summer in the record. The difference between those two years is the difference between a warm June and a June that never really got going.
Before going further, an honest note on geography: this page is about what the Aberfoyle station records, not a direct measurement of Glasgow itself. The city sits about 35.6 km from this station, and local conditions — altitude, proximity to the Clyde, urban heat — can shift actual dates by days or even a week. But for a long-term view of when summer arrives in this corner of Scotland, Aberfoyle is the best available reference, and its data is the official Met Office record.
Meteorologists define summer by temperature, not by the calendar. For this analysis, a "summer day" means a day when the maximum temperature reached at least 25°C. The first such day each year marks the real beginning of summer. The record from Aberfoyle shows just how variable that date can be, even in a climate that is not known for scorching heat.
Here is what the first and last years of the period tell us, directly from the series:
If you are planning an outdoor event near Glasgow and need warm, reliably summer-like conditions, the numbers from Aberfoyle suggest you should look at the earliest dates with caution: in 1968, summer arrived on June 11, but in 1997, it did not arrive until July 10. A 25°C day before mid-June is a gift, not a guarantee.
Beyond the first 25°C day, the overall warmth of each year tells a complementary story. Below is the annual mean temperature (average of daily mean temperatures) for each full year in the Aberfoyle record. The series is not continuous — the station has gaps — but the available years are shown in full.
The chart shows the complete annual series. The table lists the most notable years; the full series comes from Met Office.
| Year | Annual Mean Temperature (°C) |
|---|---|
| 1971 | 8.6 |
| 1972 | 8.2 |
| 1975 | 4.6 |
| 1995 | 8.8 |
| 1997 | 9.5 |
| 1998 | 9.5 |
| 2000 | 10.0 |
The extremes within this series are worth highlighting, because they frame what is possible in this climate. The five warmest years and the five coldest years, measured by annual mean temperature, are listed below exactly as they appear in the official record.
Notice that the warmest year, 2000 at 10.0°C, is also the most recent full year in the series. The 1997 and 1998 pair, both at 9.5°C, were marked by a notably late first summer day in 1997 — a reminder that a warm annual average does not guarantee an early summer.
The gap between the coldest year (1975, at 4.6°C) and the warmest (2000, at 10.0°C) is stark — more than double the annual mean temperature. If you lived near Glasgow and remember the mid-1970s as harsh, the Aberfoyle data supports that memory: 1975 sits as the coldest year in the entire record.
If you are choosing a date for a wedding, a festival, or a construction deadline that needs dry, warm weather, the Aberfoyle data gives you a clear target. In the best case — 1968 — you could rely on summer arriving by June 11. In the worst case — 1997 — you might wait until July 10. The safe window for a "first 25°C day" near Glasgow, based on this record, is somewhere in that range. The annual mean temperatures show that the warmest years tend to cluster in the late 1990s and 2000, with 2000 being the single warmest year at 10.0°C, while the coldest dip is 1975 at 4.6°C.
One more honest caveat: the record at Aberfoyle is not continuous. There are gaps (for example, no data appears between 1978 and 1994 in the annual series), so the extremes listed here are the extremes within the measured period, not necessarily all-time records for the location. Still, within the official Met Office record from 1968-01-01 to 2001-10-01, these are the facts.
Source: Met Office MIDAS (Integrated Data Archive System), station at Aberfoyle. Period analyzed: 1968-01-01 to 2001-10-01.
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© 2026 HistoClima · data: Met Office (OGL v3.0) · not affiliated with Met Office · citation permitted with source.