Cornwall is a weather station located 64 m above sea level, 2 km from Cornwall. Its records go back to 1951: 66 years of temperature are available up to 2020, along with rainfall and a comparison with two reference normals. Closed series: the records of this station end in 2020. Over 1991–2020 the annual mean temperature there is 7.9 °C, clearly higher than over 1961–1990 (6.8 °C): a difference of 1.1 °C. The warmest year of the series is 1998 (9.3 °C) and the coldest 1972 (5.6 °C). The last complete year, 2020, ranks 5 out of 66, from warmest to coldest. Over 1961–2020, the annual mean temperature changes by +0.39 °C per decade. The station ranks 20 out of 240 stations, from the fastest rise to the slowest.
Annual mean temperature since 1951
The first ten years of the series (1951–1962) average 7.2 °C; the last ten (2010–2020) average 8.3 °C, a difference of +1.2 °C. Of the ten warmest years in the series, 7 fall after 1999. The warmest is 1998 (9.3 °C). The ten-year running mean peaks at 8.3 °C (2019) and bottoms out at 6.3 °C (1972).
Annual rainfall since 1951
On average 1091 mm of rain falls per year over the 59 documented years. The wettest year, 2017, received 1382 mm; the driest, 1984, only 784 mm, which is 1.8 times less. The 1991–2020 normal (1126 mm per year) is 53 mm (4.9 %) above the 1961–1990 one (1073 mm). Over 1991–2020, June is on average the wettest month (104 mm) and March the driest (78 mm). Between 1998 and 2017, 11 years out of 20 exceeded the series average.
Monthly normals: 1961–1990 against 1991–2020
The table compares, month by month, the mean temperature and the rainfall total of two thirty-year reference periods. The difference column shows what the recent period changes compared with the earlier one.
| Month | Temp. 1961–1990 | Temp. 1991–2020 | Difference | Rain 1961–1990 | Rain 1991–2020 | Difference |
|---|---|---|---|---|---|---|
| January | −9.1 °C | −7.8 °C | +1.3 °C | 92 mm | 96 mm | +4 mm |
| February | −8.0 °C | −6.5 °C | +1.5 °C | 81 mm | 83 mm | +2 mm |
| March | −1.6 °C | −0.9 °C | +0.7 °C | 73 mm | 78 mm | +5 mm |
| April | 6.3 °C | 6.9 °C | +0.6 °C | 80 mm | 96 mm | +16 mm |
| May | 13.3 °C | 14.3 °C | +1.0 °C | 80 mm | 91 mm | +11 mm |
| June | 18.4 °C | 19.4 °C | +1.0 °C | 86 mm | 104 mm | +18 mm |
| July | 21.3 °C | 22.1 °C | +0.8 °C | 88 mm | 103 mm | +15 mm |
| August | 20.1 °C | 21.2 °C | +1.1 °C | 105 mm | 89 mm | −16 mm |
| September | 15.4 °C | 16.9 °C | +1.5 °C | 97 mm | 98 mm | +1 mm |
| October | 9.2 °C | 9.9 °C | +0.7 °C | 81 mm | 103 mm | +22 mm |
| November | 2.5 °C | 3.3 °C | +0.8 °C | 98 mm | 87 mm | −11 mm |
| December | −5.8 °C | −3.5 °C | +2.3 °C | 112 mm | 98 mm | −14 mm |
The largest temperature change is in December (+2.3 °C) and the smallest in April (+0.6 °C); over the year the mean difference is +1.1 °C, and 12 months out of twelve are warmer than before. For rainfall, the largest difference is in October (+22 mm) and the smallest in August (−16 mm).
Records at Cornwall
- Warmest year: 9.3 °C, in 1998
- Coldest year: 5.6 °C, in 1972
- Driest year: 784 mm, in 1984
- Wettest year: 1382 mm, in 2017
- Warmest month: 24.7 °C, in July 2020
- Coldest month: −15.9 °C, in January 1994
- Wettest month: 233 mm, in January 1978
- Hottest day: 37.5 °C, on 10 July 2020
- Coldest day: −43.3 °C, on 15 January 1957
- Heaviest rain in one day: 110.4 mm, on 14 September 1979
3.7 °C separate the warmest year of the series from the coldest. Between the hottest and the coldest day on record, the range reaches 80.8 °C.
Temperature trend over 1961–2020
The regression line of annual mean temperature changes by +0.39 °C per decade between 1961 and 2020, about +2.3 °C over the whole period. That is faster than the median of the 240 stations (+0.25 °C per decade), by 0.14 °C per decade: the station ranks 20 out of 240.
Data source and licence
Data source: Environment and Climate Change Canada (dataset “AHCCD (ahccd-monthly) + climate-daily”), licence Open Government Licence – Canada. Last updated: 29 October 2026.
The data for Cornwall are shown as the source publishes them; this site does not correct them. A year is kept only if at least eleven months of measurements are available, and a normal is computed only with at least twenty years of data out of its thirty. Temperatures are rounded to 0.1 °C and rainfall to the millimetre. The station is one of 240 stations in Canada: the overview page lets you compare them.
Frequently asked questions
What is the annual mean temperature at Cornwall?
Over 1991–2020, the annual mean temperature at Cornwall is 7.9 °C. It was 6.8 °C over 1961–1990, a difference of +1.1 °C.
What is the warmest year ever measured at Cornwall?
Since records began in 1951, the warmest year at Cornwall is 1998, at 9.3 °C on average. The coldest is 1972 (5.6 °C).
Is the climate at Cornwall getting warmer?
Yes: at Cornwall, the annual mean temperature rises by 0.39 °C per decade between 1961 and 2020, +2.3 °C in total. 7 of the 10 warmest years in the series fall after 1999.
Towns near this station
Neighbouring stations