Norristown weather by month
Measured at Pottstown/Heritage Fld
Averages and records for each calendar month at Pottstown/Heritage Fld, United States, from 1999 to 2026. The warmest month is July, averaging 29.9°C; the coolest is January at 3.6°C.
| Month | Avg high | Avg low | Record high | Record low | Years |
|---|---|---|---|---|---|
| January | 3.6°C | −5.3°C | 21.7°C6 January 2007 | −21.6°C31 January 2019 | 27 / 27 |
| February | 5.4°C | −4.4°C | 25.6°C21 February 2018 | −18.8°C1 February 2019 | 26 / 27 |
| March | 11.0°C | −0.1°C | 28.9°C29 March 2025 | −17.7°C6 March 2015 | 28 / 28 |
| April | 17.3°C | 5.1°C | 33.3°C27 April 2009 | −6.0°C6 April 2016 | 28 / 28 |
| May | 22.6°C | 10.5°C | 34.4°C31 May 2011 | −1.1°C4 May 2002 | 27 / 28 |
| June | 27.1°C | 15.5°C | 36.7°C9 June 2011 | 4.4°C1 June 2020 | 28 / 28 |
| July | 29.9°C | 18.5°C | 40.6°C22 July 2011 | 8.9°C3 July 2001 | 27 / 28 |
| August | 28.5°C | 17.4°C | 38.3°C9 August 2001 | 8.3°C21 August 2000 | 27 / 28 |
| September | 24.8°C | 13.3°C | 36.7°C1 September 2010 | 1.1°C21 September 2020 | 26 / 28 |
| October | 18.5°C | 7.0°C | 32.8°C2 October 2019 | −3.8°C19 October 2015 | 27 / 27 |
| November | 12.4°C | 1.4°C | 28.3°C6 November 2024 | −11.6°C23 November 2018 | 27 / 27 |
| December | 6.4°C | −2.6°C | 22.8°C5 December 2001 | −17.8°C14 December 2005 | 27 / 27 |
Years shows the number behind the average high, then the number holding a record for that month. They differ because a year contributes an average only when the month has at least 25 days of readings, while a single reading is enough to set a record. The average low is withheld on the same 25-day rule and is counted separately again; it is shown as a dash where the archive cannot support it. Across the twelve months here the averages rest on 26 to 28 years each.
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Climate at nearby stations
The closest stations with twelve months of archive of their own, nearest first.
Every figure on this page is computed from NOAA GHCN-Daily observations stored per station, per year, per month. Nothing is modelled, interpolated or estimated, and a month the archive never covered is left out rather than filled in. A station appears here only once all twelve months carry an average from at least 10 years. See how this is built.