Castlemaine Prison is a weather station located 330 m above sea level, 1 km from Chewton. Its records go back to 1967: 46 years of temperature are available up to 2025, along with rainfall and a comparison with two reference normals. Over 1991–2020 the annual mean temperature there is 13.9 °C, barely higher than over 1961–1990 (13.6 °C): a difference of 0.2 °C. The warmest year of the series is 2014 (14.8 °C) and the coldest 1996 (12.7 °C). The last complete year, 2017, ranks 1 out of 46, from warmest to coldest. Over 1967–2025, the annual mean temperature changes by +0.14 °C per decade. The station ranks 170 out of 227 stations, from the fastest rise to the slowest.
Annual mean temperature since 1967
The first ten years of the series (1967–1976) average 13.7 °C; the last ten (2007–2017) average 14.2 °C, a difference of +0.5 °C. Of the ten warmest years in the series, 7 fall after 1999. The warmest is 2014 (14.8 °C). The ten-year running mean peaks at 14.1 °C (2015) and bottoms out at 13.3 °C (1993).
Annual rainfall since 1967
On average 595 mm of rain falls per year over the 56 documented years. The wettest year, 1973, received 970 mm; the driest, 1967, only 251 mm, which is 3.9 times less. The 1991–2020 normal (584 mm per year) is 24 mm (3.9 %) below the 1961–1990 one (608 mm). Over 1991–2020, August is on average the wettest month (62 mm) and March the driest (30 mm). Between 2004 and 2025, 7 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 | 20.2 °C | 20.7 °C | +0.5 °C | 37 mm | 42 mm | +5 mm |
| February | 20.8 °C | 20.6 °C | −0.2 °C | 34 mm | 40 mm | +6 mm |
| March | 18.0 °C | 17.8 °C | −0.2 °C | 39 mm | 30 mm | −9 mm |
| April | 13.9 °C | 13.9 °C | 0.0 °C | 48 mm | 36 mm | −12 mm |
| May | 10.5 °C | 10.8 °C | +0.3 °C | 63 mm | 54 mm | −9 mm |
| June | 7.8 °C | 8.3 °C | +0.5 °C | 49 mm | 61 mm | +12 mm |
| July | 7.1 °C | 7.6 °C | +0.5 °C | 59 mm | 58 mm | −1 mm |
| August | 8.4 °C | 8.3 °C | −0.1 °C | 70 mm | 62 mm | −8 mm |
| September | 10.3 °C | 10.5 °C | +0.2 °C | 59 mm | 61 mm | +2 mm |
| October | 12.8 °C | 13.2 °C | +0.4 °C | 65 mm | 49 mm | −16 mm |
| November | 15.8 °C | 16.1 °C | +0.3 °C | 43 mm | 52 mm | +9 mm |
| December | 18.1 °C | 18.5 °C | +0.4 °C | 42 mm | 39 mm | −3 mm |
The largest temperature change is in June (+0.5 °C) and the smallest in February (−0.2 °C); over the year the mean difference is +0.2 °C, and 8 months out of twelve are warmer than before. For rainfall, the largest difference is in June (+12 mm) and the smallest in October (−16 mm).
Records at Castlemaine Prison
- Warmest year: 14.8 °C, in 2014
- Coldest year: 12.7 °C, in 1996
- Driest year: 251 mm, in 1967
- Wettest year: 970 mm, in 1973
- Warmest month: 24.0 °C, in January 1981
- Coldest month: 5.6 °C, in July 1982
- Wettest month: 208 mm, in January 2011
- Hottest day: 43.9 °C, on 7 February 2009
- Coldest day: −6.3 °C, on 21 July 1982
- Heaviest rain in one day: 101.0 mm, on 5 February 2011
2.1 °C separate the warmest year of the series from the coldest. Between the hottest and the coldest day on record, the range reaches 50.2 °C.
Temperature trend over 1967–2025
The regression line of annual mean temperature changes by +0.14 °C per decade between 1967 and 2025, about +0.8 °C over the whole period. That is slower than the median of the 227 stations (+0.19 °C per decade), by 0.05 °C per decade: the station ranks 170 out of 227.
The last 24 months against the 1991–2020 normal
Over the last 24 months (October 2024 to September 2026), 8 months out of 8 were warmer than the 1991–2020 normal for the same month; the mean departure is +1.1 °C. The highest departure was in September 2026 (+2.2 °C); the lowest, in August 2025 (+0.3 °C). The last twelve months add up to 678 mm of rain, which is 116 % of the 1991–2020 annual normal (584 mm).
| Month | Temperature | Departure from normal | Rain | Normal rain |
|---|---|---|---|---|
| October 2024 | – | – | 38 mm | 49 mm |
| November 2024 | – | – | 67 mm | 52 mm |
| December 2024 | – | – | 32 mm | 39 mm |
| January 2025 | – | – | 25 mm | 42 mm |
| February 2025 | 21.9 °C | +1.3 °C | 28 mm | 40 mm |
| March 2025 | – | – | 36 mm | 30 mm |
| April 2025 | – | – | 21 mm | 36 mm |
| May 2025 | – | – | 9 mm | 54 mm |
| June 2025 | – | – | 59 mm | 61 mm |
| July 2025 | – | – | 96 mm | 58 mm |
| August 2025 | 8.6 °C | +0.3 °C | 64 mm | 62 mm |
| September 2025 | – | – | 30 mm | 61 mm |
| October 2025 | – | – | 50 mm | 49 mm |
| November 2025 | – | – | 97 mm | 52 mm |
| December 2025 | – | – | 56 mm | 39 mm |
| January 2026 | – | – | 2 mm | 42 mm |
| February 2026 | 21.2 °C | +0.6 °C | 34 mm | 40 mm |
| March 2026 | 18.2 °C | +0.4 °C | 73 mm | 30 mm |
| April 2026 | – | – | 17 mm | 36 mm |
| May 2026 | 12.6 °C | +1.8 °C | 56 mm | 54 mm |
| June 2026 | – | – | 103 mm | 61 mm |
| July 2026 | 8.1 °C | +0.5 °C | 86 mm | 58 mm |
| August 2026 | 9.7 °C | +1.4 °C | 86 mm | 62 mm |
| September 2026 | 12.7 °C | +2.2 °C | 18 mm | 61 mm |
Data source and licence
Data source: Bureau of Meteorology (ACORN-SAT) and NOAA NCEI (GHCN-Daily) (dataset “ACORN-SAT v2 daily (homogenised) + GHCN-Daily”), licence CC BY 4.0; Public domain (NOAA NCEI). Last updated: 29 October 2026.
The data for Castlemaine Prison 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 227 stations in Australia: the overview page lets you compare them.
Frequently asked questions
What is the annual mean temperature at Castlemaine Prison?
Over 1991–2020, the annual mean temperature at Castlemaine Prison is 13.9 °C. It was 13.6 °C over 1961–1990, a difference of +0.2 °C.
What is the warmest year ever measured at Castlemaine Prison?
Since records began in 1967, the warmest year at Castlemaine Prison is 2014, at 14.8 °C on average. The coldest is 1996 (12.7 °C).
Is the climate at Castlemaine Prison getting warmer?
Yes: at Castlemaine Prison, the annual mean temperature rises by 0.14 °C per decade between 1967 and 2025, +0.8 °C in total. 7 of the 10 warmest years in the series fall after 1999.
Towns near this station
Neighbouring stations