Chatham is a weather station located 180 m above sea level, 5 km from Chatham. Its records go back to 1890: 110 years of temperature are available up to 2015, along with rainfall and a comparison with two reference normals. Closed series: the records of this station end in 2015. Over 1991–2020 the annual mean temperature there is 9.9 °C, clearly higher than over 1961–1990 (8.8 °C): a difference of 1.1 °C. The warmest year of the series is 1991 (12.0 °C) and the coldest 1917 (6.6 °C). The last complete year, 2015, ranks 29 out of 110, from warmest to coldest. Over 1961–2015, the annual mean temperature changes by +0.38 °C per decade. The station ranks 24 out of 240 stations, from the fastest rise to the slowest.
Annual mean temperature since 1890
The first ten years of the series (1890–1901) average 8.0 °C; the last ten (2001–2015) average 10.3 °C, a difference of +2.4 °C. Of the ten warmest years in the series, 3 fall after 1999. The warmest is 1991 (12.0 °C). The ten-year running mean peaks at 10.4 °C (2007) and bottoms out at 7.9 °C (1904).
Annual rainfall since 1890
On average 855 mm of rain falls per year over the 71 documented years. The wettest year, 1985, received 1159 mm; the driest, 1963, only 540 mm, which is 2.1 times less. Over 1961–1990, August is on average the wettest month (101 mm) and January the driest (53 mm). Between 1967 and 1996, 17 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 | −5.3 °C | −3.8 °C | +1.5 °C | 53 mm | – | – |
| February | −4.2 °C | −2.9 °C | +1.3 °C | 56 mm | – | – |
| March | 1.3 °C | 2.4 °C | +1.1 °C | 71 mm | – | – |
| April | 7.4 °C | 8.4 °C | +1.0 °C | 76 mm | – | – |
| May | 14.3 °C | 15.0 °C | +0.7 °C | 73 mm | – | – |
| June | 19.4 °C | 20.6 °C | +1.2 °C | 80 mm | – | – |
| July | 21.9 °C | 22.5 °C | +0.6 °C | 81 mm | – | – |
| August | 20.7 °C | 21.7 °C | +1.0 °C | 101 mm | – | – |
| September | 16.8 °C | 18.1 °C | +1.3 °C | 82 mm | – | – |
| October | 10.7 °C | 11.6 °C | +0.9 °C | 55 mm | – | – |
| November | 4.9 °C | 5.3 °C | +0.4 °C | 84 mm | – | – |
| December | −2.1 °C | 0.0 °C | +2.1 °C | 91 mm | – | – |
The largest temperature change is in December (+2.1 °C) and the smallest in November (+0.4 °C); over the year the mean difference is +1.1 °C, and 12 months out of twelve are warmer than before.
Records at Chatham
- Warmest year: 12.0 °C, in 1991
- Coldest year: 6.6 °C, in 1917
- Driest year: 540 mm, in 1963
- Wettest year: 1159 mm, in 1985
- Warmest month: 25.5 °C, in July 1921
- Coldest month: −12.1 °C, in January 1912
- Wettest month: 242 mm, in August 1987
5.4 °C separate the warmest year of the series from the coldest. Daily records are not part of the dataset for this station: only annual and monthly extremes are shown.
Temperature trend over 1961–2015
The regression line of annual mean temperature changes by +0.38 °C per decade between 1961 and 2015, about +2.1 °C over the whole period. That is faster than the median of the 240 stations (+0.25 °C per decade), by 0.13 °C per decade: the station ranks 24 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 Chatham 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 Chatham?
Over 1991–2020, the annual mean temperature at Chatham is 9.9 °C. It was 8.8 °C over 1961–1990, a difference of +1.1 °C.
What is the warmest year ever measured at Chatham?
Since records began in 1890, the warmest year at Chatham is 1991, at 12.0 °C on average. The coldest is 1917 (6.6 °C).
Is the climate at Chatham getting warmer?
Yes: at Chatham, the annual mean temperature rises by 0.38 °C per decade between 1961 and 2015, +2.1 °C in total. 3 of the 10 warmest years in the series fall after 1999.
Towns near this station
Neighbouring stations