September Summary
Average temperature, below average wind run, 60% of expected rainfall.
(September compared to my records from the past 10 years.)
- This September was equal to my average temperature of 9.8c.
- The coldest temperature was -2.7C which is lower than the expected minimum for September, -1C.
- The highest temperature was 24.4C, my average September maximum is 24.3C.
- Seven air frosts (air temperature at or below 0) were recorded, my average is 3.
- No days failed to reach or exceed 10C, my average is 1.
- Seventeen days reached or exceeded 15C, my average is 16.
- Nine days reached or exceeded 20C, my average is 5.
- Wind run was 91% of my average of 4485km with 4096km, the windiest September was 2016 with 5291km.
- The barometer recorded about average pressure for the month with 1010.6hPa. My average is 1010.3hPa.
- Rainfall was 60% of the average expected total of 42mm with 25.0mm.
- The wettest September in the past 10 years is 2015 with 71mm and in all my records, 2000 with 101mm.
| September 2021 Summary Temperature | |
|---|---|
| Mean | 9.8 C |
| Mean Maximum | 16.6 C |
| Mean Minimum | 3.4 C |
| Maximum High | 24.4 C (21st) |
| Maximum Low | 9.6 C (22nd) |
| Minimum High | 10 C (14th) |
| Minimum Low | -2.7 C (18th) |
| Wind Speed and Direction | |
| Maximum Gust | 69 km/h (25th) |
| Mean | 6.0 km/h |
| Wind Run | 4096 km |
| Max Daily Windrun | 267 km (25th) |
| Prevailing Direction | East North East |
| Barometer | |
| Maximum | 1039.3 hPa (2nd) |
| Minimum | 981.0 hPa (7th) |
| Mean | 1010.6 hPa |
| Max Daily Change | +21.8 hPa (26th) |
| Rainfall | |
| Days with Measured Rainfall (0.2mm or more) |
9 |
| Max Daily Rainfall | 10.2 mm (13th) |
| Monthly Rainfall | 25.0 mm |
| Humidity | |
| Maximum | 95 % |
| Minimum | 33 % (4th) |
| September Daily Observations | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Temperature | Wind | Rainfall | Barometer | |||||||||
| Date | Min | Max | Mean | Mean (Km/h) | Gust (Km/h) | Run (km) | Prevailing Dir | 10 Minute Max (mm) | Total (mm) | Min (hPa) | Max (hPa) | Change (hPa) |
| 1 | 4.6 | 11.3 | 7.9 | 10.1 | 37 | 230 | East Nth East | 0 | 0 | 1030.7 | 1035.3 | -4.6 |
| Cloud breaking to a mostly sunny day with a fresh cool NE wind. Spring likely to be drier and warmer than average, says NIWA |
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| 2 | 2.2 | 13.2 | 7.7 | 4.8 | 24 | 108 | South Sth West | 0.2 | 0.4 | 1030.5 | 1039.3 | +8.8 |
| Late morning shower. Cloud breaking in the afternoon. Light southerly winds turning NE in the afternoon. | ||||||||||||
| 3 | 3.1 | 14.3 | 9.2 | 7.0 | 31 | 160 | East Nth East | 0 | 0 | 1038.8 | 1032.2 | -6.6 |
| Some morning cloud clearing to a sunny day with a cool NE wind. 2021 blows past 2020 to take warmest winter record |
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| 4 | -0.2 | 21.0 | 10.2 | 3.6 | 32 | 81 | North Nth West | 0 | 0 | 1022.4 | 1031.9 | -9.5 |
| Sunny and mild after a light morning frost. Mostly light northerly winds. | ||||||||||||
| 5 | 5.9 | 20.7 | 12.8 | 2.9 | 16 | 65 | East Nth East | 0 | 0 | 1022.7 | 1026.5 | +3.8 |
| Some high cloud, mild with light winds tending NE. | ||||||||||||
| 6 | 5.1 | 20.0 | 12.1 | 6.5 | 34 | 147 | East Nth East | 0 | 0 | 1002.0 | 1023.1 | -21.1 |
| High overcast with a nor'west arch in the afternoon. Winds tending NE but mild northerly winds at times. | ||||||||||||
| 7 | 6.8 | 21.1 | 14.8 | 11.2 | 54 | 257 | East Nth East | 0 | 0 | 981.0 | 1001.7 | -20.7 |
| Sunny with a fresh mild nor'west wind in the afternoon. | ||||||||||||
| 8 | 6.4 | 10.2 | 6.4 | 4.8 | 46 | 109 | South Sth West | 0.4 | 4.4 | 984.1 | 1002.4 | +18.3 |
| Cold southerly change in the morning with a period of rain. Cloud breaking from midday to a mostly sunny cool afternoon with the wind dying away. 'Four seasons in one day': Snow, gales and heavy rain for many as cold snap hits |
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| 9 | 1.1 | 21.5 | 11.5 | 9.1 | 55 | 209 | East Nth East | 0 | 0 | 988.9 | 1001.9 | -13.0 |
| Mostly cloudy with fresh nor'west winds in the afternoon. | ||||||||||||
| 10 | 6.8 | 19.8 | 13.6 | 8.3 | 48 | 189 | North Nth West | 0.2 | 0.6 | 981.8 | 991.7 | +9.9 |
| Mostly cloudy with mild northerly winds, fresh at times. A few spots of rain around midday. A change to cooler southerly winds in the afternoon with a period of rain at night. Trees down, power out, sheds destroyed - what caused the fierce winds of the past 24 hours |
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| 11 | 0.6 | 14.6 | 8.2 | 4.3 | 23 | 97 | South Sth West | 0 | 0 | 992.3 | 1010.1 | +17.8 |
| Sunny with light southerly winds in the afternoon. | ||||||||||||
| 12 | 5.6 | 20.1 | 12.5 | 6.3 | 30 | 143 | East Nth East | 0 | 0 | 994.1 | 1010.0 | -15.9 |
| High cloud increasing in the afternoon, Northerly winds at times in the afternoon. | ||||||||||||
| 13 | 6.7 | 19.0 | 12.4 | 7.0 | 45 | 159 | East Nth East | 1.6 | 10.2 | 992.1 | 1006.3 | +14.2 |
| A period of heavy rain in the morning clearing by midday then warm northerly winds turning cooler NE later in the afternoon. South escapes brunt of gales and rain but cold snap and snow may be on the way. |
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| 14 | -0.4 | 10.0 | 5.2 | 6.5 | 34 | 149 | South Sth West | 0.6 | 7.4 | 1007.5 | 1024.7 | +17.2 |
| Morning rain then showers clearing early afternoon and cloud breaking and clearing in the evening. | ||||||||||||
| 15 | -2.0 | 12.5 | 5.0 | 3.4 | 24 | 77 | East Nth East | 0 | 0 | 1015.8 | 1024.5 | -8.7 |
| Morning frost then partly cloudy with a cool NE wind. Rare 'red lightning' weather phenomenon captured by Christchurch photographer |
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| 16 | -0.6 | 13.5 | 6.1 | 3.1 | 25 | 72 | South Sth West | 0 | 0 | 1012.8 | 1016.9 | -4.1 |
| Mostly cloudy but some sunny intervals, cool southerly wind. A few spots of rain in the evening. | ||||||||||||
| 17 | -1.1 | 12.0 | 5.1 | 2.2 | 20 | 49 | South Sth West | 0 | 0 | 1015.3 | 1022.2 | +7.9 |
| Cloud increasing in the morning then breaking in the afternoon. Light winds tending southerly. | ||||||||||||
| 18 | -2.7 | 12.0 | 5.5 | 6.4 | 34 | 147 | East Nth East | 0 | 0 | 1019.4 | 1024.0 | -4.6 |
| Sunny with a cool NE wind. | ||||||||||||
| 19 | 6.2 | 16.6 | 11.1 | 6.9 | 39 | 158 | East Nth East | 0 | 0 | 1001.4 | 1019.2 | -17.8 |
| Mostly cloudy but some sunny intervals in the morning. Wind varying between cool NE and warmer northerly. | ||||||||||||
| 20 | 6.7 | 19.4 | 12.0 | 6.0 | 31 | 137 | East Nth East | 0 | 0 | 1001.3 | 1008.3 | +7.0 |
| Sunny and mild though cooler later in the afternoon with a freshening NE wind. | ||||||||||||
| 21 | 7.2 | 24.4 | 14.8 | 6.1 | 35 | 138 | East Nth East | 0 | 0 | 995.9 | 1005.6 | -9.7 |
| Sunny morning and mild in the afternoon with winds turning NW with increasing high cloud. | ||||||||||||
| 22 | 9.6 | 15.0 | 11.8 | 8.3 | 32 | 189 | East Nth East | 0 | 0 | 1001.8 | 1009.5 | +7.7 |
| Cloudy with a cool NE wind. | ||||||||||||
| 23 | 7.1 | 16.7 | 11.3 | 4.8 | 26 | 110 | East Nth East | 0.2 | 0.2 | 988.3 | 1006.5 | -18.2 |
| Morning light rain and drizzle clearing by midday with brighter spells. Cloud increasing in the afternoon. NE wind. | ||||||||||||
| 24 | 4.4 | 22.2 | 11.7 | 5.6 | 39 | 127 | East Nth East | 0 | 0 | 987.2 | 1003.8 | +16.6 |
| Sunny with northerly winds turning fresher NE in the afternoon. | ||||||||||||
| 25 | 8.5 | 19.1 | 14.7 | 11.7 | 69 | 267 | North Nth West | 0 | 0 | 990.6 | 1002.3 | -11.7 |
| Sunny with some high cloud in the afternoon. Gale nor'west winds from late morning dying away later in the afternoon. Highest wind gust to date this year. Fire crews halt Prebbleton blaze, as South Island hit by gale force winds |
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| 26 | 2.3 | 11.5 | 7.4 | 4.5 | 30 | 99 | South Sth West | 0.2 | 0.2 | 997.0 | 1018.8 | +21.8 |
| Sunny intervals in the morning but cloud increasing with a light shower around midday. Cloud breaking later in the afternoon. Cool southerly wind. | ||||||||||||
| 27 | 0.8 | 13.9 | 6.8 | 3.7 | 23 | 85 | East Nth East | 0.2 | 0.2 | 1019.0 | 1023.4 | +4.4 |
| Early shower before dawn. Partly cloudy and cool with light NE winds in the afternoon | ||||||||||||
| 28 | 0.4 | 15.7 | 7.6 | 2.6 | 25 | 60 | East Nth East | 0 | 0 | 1015.4 | 1020.8 | -5.4 |
| Sunny with some cloud, light cool NE wind. | ||||||||||||
| 29 | 0.0 | 22.0 | 10.8 | 4.9 | 40 | 135 | North Nth West | 0 | 0 | 1004.9 | 1015.3 | -10.4 |
| Sunny with NE wind turning mild nor'west from early afternoon. | ||||||||||||
| 30 | 5.2 | 14.9 | 9.3 | 5.6 | 43 | 127 | South Sth West | 0.4 | 1.4 | 1008.3 | 1018.9 | +10.6 |
| Early showers clearing and cloud breaking to a sunny afternoon with light southerly winds. | ||||||||||||
