August is one of the warmer months of the year in Grantham, with average highs near 21.1°C and lows around 11.6°C (mean 16.4°C). It is about average for rainfall, averaging 61 mm of rainfall and 80% relative humidity across the period.
August is one of the warmer months of the year in Grantham. Across 45 years of records, the warmest August in Grantham was 1997 — when the month averaged 18.7°C — while the coldest was 1986 at 13.4°C. Typical August days reach 21.1°C with nights near 11.6°C. The long-term trend is warming, about 0.3°C per decade.
August is about average for rainfall in Grantham, averaging 61 mm of rainfall. The wettest August on record was 2004 with 153 mm, while the driest was 1995 at 10 mm.
Relative humidity in Grantham during August averages 80%. The most humid August was 2002 at 84%, and the least humid were 1990 and 1992 at 75%.
August receives about 4.2 kWh/m²/day of solar energy in Grantham. The sunniest August was 1995 at 5 kWh/m²/day, and the cloudiest were 1986 and 1987 at 3.4.
Average wind speed in Grantham during August is 3.1 m/s. The windiest August was 1985 at 4.3 m/s, while the calmest were 1984 and 2002 at 2.3 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 15.5°C | 16.5°C | 16.6°C | 16.1°C | 17.2°C | +1.7°C |
| Avg High | 20.2°C | 21.4°C | 21.2°C | 20.8°C | 22.1°C | +1.9°C |
| Avg Low | 10.9°C | 11.6°C | 12.0°C | 11.5°C | 12.4°C | +1.5°C |
| Avg Rain | 60 mm | 52 mm | 75 mm | 68 mm | 42 mm | -18 mm |
August temperatures in Grantham have risen by about 1.1°C between 1981–1985 and 2021–2025.
August has ranged from a record low of 5.4°C (2012) to a record high of 31.3°C (1990).
Rainfall in August is about average for rainfall, averaging 61 mm, with a wettest year of 153 mm.
One of the best times to visit Grantham
August is one of the best times to visit Grantham. Expect days averaging 21.1°C and nights around 11.6°C (mean 16.4°C) — warmer than Grantham's yearly average — with moderate rainfall (61 mm), so conditions are generally comfortable for sightseeing and outdoor plans.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 22.6°C | 17.5°C | 12.3°C | 28.6°C | 9.9°C | 17 mm | 75% | 3 m/s | 4.4 |
| 2024 | 22.0°C | 17.0°C | 12.0°C | 29.0°C | 8.6°C | 25 mm | 79% | 3.3 m/s | 4.2 |
| 2023 | 21.5°C | 16.6°C | 11.8°C | 26.2°C | 8.3°C | 62 mm | 80% | 3.1 m/s | 4.3 |
| 2022 | 23.8°C | 18.4°C | 13.1°C | 29.3°C | 8.5°C | 39 mm | 76% | 2.5 m/s | 4.9 |
| 2021 | 20.4°C | 16.1°C | 11.9°C | 22.9°C | 9.1°C | 36 mm | 82% | 3 m/s | 3.7 |
| 2020 | 22.1°C | 17.7°C | 13.3°C | 28.6°C | 7.1°C | 74 mm | 81% | 3.7 m/s | 4 |
| 2019 | 22.2°C | 17.3°C | 12.3°C | 28.9°C | 9.4°C | 62 mm | 78% | 3.5 m/s | 4.5 |
| 2018 | 21.7°C | 16.9°C | 12.2°C | 26.5°C | 7.9°C | 61 mm | 79% | 2.8 m/s | 4.2 |
| 2017 | 19.8°C | 15.3°C | 10.8°C | 24.4°C | 6.9°C | 70 mm | 80% | 3.1 m/s | 4.2 |
| 2016 | 21.5°C | 16.7°C | 12.0°C | 26.6°C | 8.4°C | 59 mm | 80% | 3.3 m/s | 4.6 |
| 2015 | 20.9°C | 16.1°C | 11.2°C | 26.9°C | 8.4°C | 74 mm | 79% | 3.1 m/s | 3.9 |
| 2014 | 19.1°C | 14.8°C | 10.5°C | 22.6°C | 6.1°C | 85 mm | 79% | 3.6 m/s | 4 |
| 2013 | 21.5°C | 16.7°C | 11.9°C | 28.8°C | 8.5°C | 49 mm | 80% | 3 m/s | 4.3 |
| 2012 | 21.2°C | 16.6°C | 12.0°C | 26.7°C | 5.4°C | 68 mm | 81% | 3 m/s | 4 |
| 2011 | 20.3°C | 15.7°C | 11.0°C | 25.8°C | 7.2°C | 57 mm | 78% | 3 m/s | 3.9 |
| 2010 | 19.8°C | 15.3°C | 10.9°C | 24.2°C | 7.1°C | 92 mm | 81% | 3.4 m/s | 3.9 |
| 2009 | 21.5°C | 16.9°C | 12.3°C | 25.3°C | 8.5°C | 71 mm | 81% | 3.3 m/s | 4.2 |
| 2008 | 20.9°C | 16.7°C | 12.5°C | 24.4°C | 9.5°C | 94 mm | 82% | 3.5 m/s | 3.5 |
| 2007 | 20.5°C | 15.8°C | 11.0°C | 26.3°C | 7.9°C | 42 mm | 81% | 3.2 m/s | 4.5 |
| 2006 | 20.1°C | 15.9°C | 11.7°C | 26.4°C | 8.3°C | 104 mm | 81% | 3.3 m/s | 3.7 |
| 2005 | 21.0°C | 16.1°C | 11.1°C | 28.2°C | 8.2°C | 68 mm | 81% | 2.9 m/s | 4.4 |
| 2004 🌧️ | 21.6°C | 17.3°C | 12.9°C | 27.1°C | 8.1°C | 153 mm | 83% | 2.8 m/s | 4.1 |
| 2003 | 22.4°C | 17.5°C | 12.7°C | 30.1°C | 6.5°C | 17 mm | 80% | 2.4 m/s | 4.5 |
| 2002 | 21.6°C | 17.0°C | 12.4°C | 27.6°C | 9.3°C | 79 mm | 84% | 2.3 m/s | 3.8 |
| 2001 | 21.2°C | 16.6°C | 12.0°C | 27.7°C | 8.3°C | 76 mm | 82% | 2.6 m/s | 4 |
| 2000 | 20.9°C | 16.2°C | 11.6°C | 24.3°C | 7.7°C | 48 mm | 81% | 2.6 m/s | 4.3 |
| 1999 | 20.1°C | 15.8°C | 11.5°C | 28.0°C | 5.7°C | 95 mm | 81% | 2.7 m/s | 3.9 |
| 1998 | 20.6°C | 15.5°C | 10.5°C | 25.9°C | 5.9°C | 45 mm | 80% | 3.3 m/s | 4.5 |
| 1997 🔥 | 23.5°C | 18.7°C | 14.0°C | 28.1°C | 9.1°C | 82 mm | 81% | 2.7 m/s | 4.2 |
| 1996 | 21.1°C | 16.3°C | 11.5°C | 27.8°C | 8.6°C | 63 mm | 78% | 2.9 m/s | 4.1 |
| 1995 | 23.0°C | 17.6°C | 12.3°C | 27.8°C | 8.5°C | 10 mm | 78% | 2.7 m/s | 5 |
| 1994 | 20.0°C | 15.6°C | 11.2°C | 26.0°C | 7.4°C | 40 mm | 79% | 3.3 m/s | 4.3 |
| 1993 | 19.4°C | 14.6°C | 9.7°C | 23.3°C | 6.2°C | 54 mm | 78% | 3.1 m/s | 4.3 |
| 1992 | 20.5°C | 15.7°C | 10.9°C | 24.9°C | 7.8°C | 87 mm | 75% | 3.9 m/s | 4.2 |
| 1991 | 22.8°C | 17.3°C | 11.8°C | 26.1°C | 7.3°C | 16 mm | 76% | 2.8 m/s | 4.6 |
| 1990 | 23.3°C | 18.0°C | 12.7°C | 31.3°C | 9.5°C | 30 mm | 75% | 3 m/s | 4.6 |
| 1989 | 21.3°C | 16.2°C | 11.2°C | 25.1°C | 7.7°C | 39 mm | 77% | 3.4 m/s | 4.6 |
| 1988 | 19.7°C | 15.1°C | 10.6°C | 25.8°C | 7.9°C | 46 mm | 80% | 3.4 m/s | 4.1 |
| 1987 | 19.8°C | 15.4°C | 11.1°C | 26.7°C | 6.4°C | 62 mm | 82% | 2.9 m/s | 3.4 |
| 1986 ❄️ | 17.7°C | 13.4°C | 9.1°C | 20.5°C | 5.7°C | 105 mm | 80% | 3.4 m/s | 3.4 |
| 1985 | 18.9°C | 14.5°C | 10.2°C | 22.9°C | 8.1°C | 69 mm | 81% | 4.3 m/s | 3.8 |
| 1984 | 22.1°C | 17.2°C | 12.3°C | 25.9°C | 7.5°C | 56 mm | 80% | 2.3 m/s | 4.6 |
| 1983 | 21.7°C | 16.6°C | 11.6°C | 25.5°C | 6.9°C | 25 mm | 81% | 2.4 m/s | — |
| 1982 | 20.0°C | 15.5°C | 11.0°C | 25.6°C | 6.8°C | 73 mm | 81% | 3.4 m/s | — |
| 1981 | 20.8°C | 16.0°C | 11.3°C | 24.9°C | 7.1°C | 69 mm | 82% | 2.5 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 21.1°C with lows near 11.6°C (mean 16.4°C), based on 45 years of NASA POWER data.
August averages 61 mm of rainfall in Grantham, about average for rainfall. The wettest on record was 153 mm in 2004.
The hottest August reached 31.3°C in 1990. The coldest dipped to 5.4°C in 2012.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average August temperatures have risen by about 1.1°C. Daytime highs moved from 20.7°C to 22.1°C and overnight lows from 11.3°C to 12.2°C over the same span.
August is one of the warmer months of the year in Grantham and about average for rainfall, so plan for around 21.1°C daytime highs and 11.6°C at night.
Not quite — August is the 11th coolest month in Grantham, averaging 16.4°C.
For August in Grantham, pack light layers you can adjust through the day, with typical highs of 21.1°C and lows of 11.6°C. Bring an umbrella or light rain jacket too.
Relative humidity in August averages 80% — quite humid.
Average wind speed in August is 3.1 m/s. The windiest August on record averaged 4.3 m/s (1985).
The wettest August on record was 2004 with 153 mm. On average, August sees 61 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Grantham behaves each August, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for August specifically, along with year-by-year records and how the month has changed over the decades.
