September 2024: Weather Records and Temperatures Against Normal
September 2024 is settled: the figures use data received up to 9 November 2026, more than 45 days after the month ended, so the late station reports are in. This page compares September 2024 at weather stations worldwide with each station's own 1991 to 2020 September normal, ranks it against September of every year since 1951, and lists the weather records, events and storms of the month.
Data as of . Last revised (2026-11-09).
Key Facts
- September 2024 is settled; its data run to 9 November 2026.
- In September 2024, stations worldwide averaged +1.0 C (+1.8 F) against their 1991 to 2020 September normals, the 2nd warmest September in 74 ranked years from 1951 to 2024.
- The mean daily maximum in September 2024 was +1.1 C (+2.0 F) against normal and the mean daily minimum +0.9 C (+1.6 F).
- Among the continents in September 2024, South America was the warmest against normal, at +1.9 C (+3.4 F), and Africa the coolest, at +0.3 C (+0.5 F).
- The station furthest above its September normal in September 2024 was Powell Fld STN (United States), at +8.6 C (+15.5 F); the furthest below was Kokpekty (Kazakhstan), at -2.7 C (-4.9 F).
- Of the 8,052 stations with a full month of rain data in September 2024, 34% had less than half their normal September rain and 8% had at least twice their normal; the median station had 79% of its normal.
- 28,587 weather records were set or tied in September 2024, including 20,374 record highs and 3,009 record lows of maximum and minimum temperature, and 52 all-time records.
- In September 2024, 88% of the daily temperature records were record highs (7.2 to 1 highs to lows), against an average of 79% for September in 2014 to 2023.
- 18 extreme weather events detected by this site overlapped September 2024.
- 20 named storms had a best track position in September 2024; 11 peaked at 64 kt (119 km/h, 74 mph) or more and 5 at 96 kt (178 km/h, 110 mph) or more over their lifetime.
- The Oceanic Nino Index for ASO 2024, the three months centred on September 2024, was -0.12: neutral, outside any El Nino or La Nina episode. NOAA's relative index (RONI) for the same season was -0.67.
- Monthly mean extent in September 2024: Arctic sea ice 4.35 million sq km (1.68 million sq mi), the 4th lowest of 46 years for September; Antarctic sea ice 17.15 million sq km (6.62 million sq mi), the 2nd lowest of 46 years for September.
- Carbon dioxide at Mauna Loa averaged 422.03 ppm in September 2024, 3.53 ppm more than in September 2023.
Temperature Against Normal
September 2024, against 1991 to 2020| Band | Stations on the map |
|---|---|
| More than 3 C (5.4 F) below normal | 0 |
| 1 to 3 C (1.8 to 5.4 F) below normal | 55 |
| Within 1 C (1.8 F) of normal | 1,050 |
| 1 to 3 C (1.8 to 5.4 F) above normal | 825 |
| More than 3 C (5.4 F) above normal | 288 |
| Area | Stations | Daily maximum vs normal | Daily minimum vs normal | Mean vs normal | Rank for September (1 is warmest) |
|---|---|---|---|---|---|
| World | 6,366 | +1.1 C (+2.0 F) | +0.9 C (+1.6 F) | +1.0 C (+1.8 F) | 2nd of 74 |
| Africa | 49 | +0.3 C (+0.5 F) | +0.3 C (+0.6 F) | +0.3 C (+0.5 F) | 11th of 56 |
| Asia | 318 | +1.2 C (+2.2 F) | +0.8 C (+1.4 F) | +1.0 C (+1.8 F) | 2nd of 73 |
| Europe | 1,150 | +1.6 C (+3.0 F) | +1.0 C (+1.8 F) | +1.3 C (+2.4 F) | 2nd of 74 |
| North America | 4,442 | +1.1 C (+1.9 F) | +1.1 C (+2.0 F) | +1.1 C (+2.0 F) | 2nd of 74 |
| Oceania | 401 | +0.6 C (+1.0 F) | +1.1 C (+1.9 F) | +0.8 C (+1.5 F) | 4th of 74 |
| South America | 6 | +2.6 C (+4.7 F) | +1.2 C (+2.1 F) | +1.9 C (+3.4 F) | 3rd of 35 |
Stations are averaged in 5 degree grid cells and the cells are weighted by the cosine of their latitude. A value and a rank need cells holding at least 50% of the weight of every cell that has ever had data for September; n/a means fewer stations have reported so far. The world includes Antarctica and islands without a continent row.
| Year | Mean against the 1991 to 2020 normal |
|---|---|
| 1951 | -0.2 C (-0.3 F) |
| 1952 | -0.4 C (-0.8 F) |
| 1953 | -0.4 C (-0.7 F) |
| 1954 | -0.3 C (-0.6 F) |
| 1955 | -0.4 C (-0.8 F) |
| 1956 | -1.1 C (-2.0 F) |
| 1957 | -0.7 C (-1.2 F) |
| 1958 | -1.0 C (-1.7 F) |
| 1959 | -0.4 C (-0.8 F) |
| 1960 | -0.7 C (-1.2 F) |
| 1961 | -0.5 C (-0.9 F) |
| 1962 | -0.8 C (-1.4 F) |
| 1963 | -0.4 C (-0.7 F) |
| 1964 | -0.9 C (-1.6 F) |
| 1965 | -0.8 C (-1.4 F) |
| 1966 | -0.7 C (-1.3 F) |
| 1967 | -1.0 C (-1.8 F) |
| 1968 | -1.1 C (-2.0 F) |
| 1969 | -1.0 C (-1.8 F) |
| 1970 | -0.7 C (-1.2 F) |
| 1971 | -0.6 C (-1.0 F) |
| 1972 | -1.1 C (-2.0 F) |
| 1973 | -0.8 C (-1.5 F) |
| 1974 | -0.7 C (-1.3 F) |
| 1975 | -0.4 C (-0.7 F) |
| 1976 | -1.0 C (-1.8 F) |
| 1977 | -0.7 C (-1.3 F) |
| 1978 | -0.8 C (-1.5 F) |
| 1979 | -0.5 C (-1.0 F) |
| 1980 | -0.4 C (-0.7 F) |
| 1981 | -0.5 C (-0.9 F) |
| 1982 | -0.5 C (-1.0 F) |
| 1983 | -0.1 C (-0.3 F) |
| 1984 | -0.9 C (-1.6 F) |
| 1985 | -0.8 C (-1.5 F) |
| 1986 | -0.7 C (-1.3 F) |
| 1987 | -0.4 C (-0.8 F) |
| 1988 | -0.2 C (-0.4 F) |
| 1989 | -0.5 C (-0.8 F) |
| 1990 | -0.4 C (-0.8 F) |
| 1991 | -0.3 C (-0.5 F) |
| 1992 | -0.9 C (-1.7 F) |
| 1993 | -0.9 C (-1.6 F) |
| 1994 | -0.3 C (-0.6 F) |
| 1995 | -0.2 C (-0.3 F) |
| 1996 | -0.8 C (-1.5 F) |
| 1997 | -0.2 C (-0.4 F) |
| 1998 | +0.1 C (+0.2 F) |
| 1999 | -0.1 C (-0.2 F) |
| 2000 | -0.2 C (-0.4 F) |
| 2001 | -0.2 C (-0.4 F) |
| 2002 | 0.0 C (0.0 F) |
| 2003 | +0.0 C (+0.0 F) |
| 2004 | -0.1 C (-0.2 F) |
| 2005 | +0.5 C (+0.9 F) |
| 2006 | +0.2 C (+0.3 F) |
| 2007 | +0.2 C (+0.4 F) |
| 2008 | -0.1 C (-0.2 F) |
| 2009 | +0.3 C (+0.5 F) |
| 2010 | +0.2 C (+0.3 F) |
| 2011 | +0.1 C (+0.2 F) |
| 2012 | +0.2 C (+0.3 F) |
| 2013 | +0.1 C (+0.2 F) |
| 2014 | +0.2 C (+0.4 F) |
| 2015 | +0.5 C (+0.9 F) |
| 2016 | +0.7 C (+1.2 F) |
| 2017 | +0.4 C (+0.6 F) |
| 2018 | +0.6 C (+1.0 F) |
| 2019 | +0.5 C (+0.9 F) |
| 2020 | +0.6 C (+1.0 F) |
| 2021 | +0.3 C (+0.6 F) |
| 2022 | +0.5 C (+0.8 F) |
| 2023 | +1.2 C (+2.1 F) |
| 2024 | +1.0 C (+1.8 F) |
Furthest Above Normal
| Station | Country | Mean maximum | Maximum vs normal | Mean minimum | Minimum vs normal | Mean vs normal | Years of normal |
|---|---|---|---|---|---|---|---|
| Powell Fld STN | United States | 31.9 C (89.5 F) | +8.7 C (+15.6 F) | 14.2 C (57.6 F) | +8.5 C (+15.4 F) | +8.6 C (+15.5 F) | 30 |
| Chester | United States | 32.5 C (90.6 F) | +6.7 C (+12.0 F) | 13.9 C (57.1 F) | +9.2 C (+16.5 F) | +7.9 C (+14.2 F) | 30 |
| Temosachi (Obs) | Mexico | 34.8 C (94.6 F) | +4.5 C (+8.0 F) | 23.2 C (73.8 F) | +8.7 C (+15.6 F) | +6.6 C (+11.8 F) | 28 |
| Sidney | United States | 31.9 C (89.4 F) | +7.7 C (+13.8 F) | 12.6 C (54.6 F) | +5.4 C (+9.7 F) | +6.5 C (+11.7 F) | 29 |
| Kirovohrad | Ukraine | 28.1 C (82.5 F) | +6.5 C (+11.7 F) | 14.4 C (57.8 F) | +5.1 C (+9.3 F) | +5.8 C (+10.5 F) | 25 |
| Zhytomyr | Ukraine | 26.3 C (79.4 F) | +6.8 C (+12.2 F) | 13.3 C (56.0 F) | +4.6 C (+8.3 F) | +5.7 C (+10.3 F) | 25 |
| Waskish 4NE | United States | 25.4 C (77.7 F) | +5.1 C (+9.2 F) | 11.4 C (52.6 F) | +5.8 C (+10.5 F) | +5.5 C (+9.9 F) | 28 |
| Baudette Intl AP | United States | 25.3 C (77.6 F) | +5.8 C (+10.5 F) | 12.6 C (54.7 F) | +5.1 C (+9.2 F) | +5.5 C (+9.8 F) | 25 |
| Mc Intosh 6 SE | United States | 30.4 C (86.8 F) | +6.4 C (+11.5 F) | 12.7 C (54.9 F) | +4.3 C (+7.7 F) | +5.3 C (+9.6 F) | 30 |
| Mildred 7 NNW | United States | 31.0 C (87.7 F) | +6.7 C (+12.1 F) | 9.9 C (49.9 F) | +3.9 C (+7.0 F) | +5.3 C (+9.5 F) | 28 |
Furthest Below Normal
| Station | Country | Mean maximum | Maximum vs normal | Mean minimum | Minimum vs normal | Mean vs normal | Years of normal |
|---|---|---|---|---|---|---|---|
| Kokpekty | Kazakhstan | 18.5 C (65.4 F) | -2.1 C (-3.8 F) | 0.4 C (32.7 F) | -3.4 C (-6.1 F) | -2.7 C (-4.9 F) | 28 |
| Elizabeth City | United States | 25.9 C (78.7 F) | -2.2 C (-3.9 F) | 15.6 C (60.1 F) | -2.6 C (-4.8 F) | -2.4 C (-4.4 F) | 29 |
| East London | South Africa | 13.0 C (55.3 F) | -3.0 C (-5.4 F) | 7.0 C (44.6 F) | -1.8 C (-3.2 F) | -2.4 C (-4.3 F) | 30 |
| Kingston Springs | United States | 27.1 C (80.8 F) | -1.6 C (-2.9 F) | 11.4 C (52.5 F) | -2.9 C (-5.3 F) | -2.3 C (-4.1 F) | 29 |
| Jinghe | China | 24.5 C (76.0 F) | -1.0 C (-1.9 F) | 8.4 C (47.1 F) | -3.1 C (-5.6 F) | -2.1 C (-3.7 F) | 30 |
| Boyce 3 WNW | United States | 28.4 C (83.2 F) | -2.0 C (-3.7 F) | 18.7 C (65.6 F) | -1.8 C (-3.2 F) | -1.9 C (-3.5 F) | 30 |
| Stykkisholmur | Iceland | 9.1 C (48.4 F) | -1.6 C (-2.9 F) | 4.0 C (39.2 F) | -2.0 C (-3.6 F) | -1.8 C (-3.3 F) | 30 |
| Pamplona | Spain | 21.8 C (71.3 F) | -2.9 C (-5.3 F) | 11.6 C (52.8 F) | -0.5 C (-1.0 F) | -1.7 C (-3.1 F) | 30 |
| Huesca | Spain | 23.8 C (74.8 F) | -2.2 C (-4.0 F) | 12.4 C (54.3 F) | -1.1 C (-2.0 F) | -1.7 C (-3.0 F) | 29 |
| Balhash | Kazakhstan | 20.1 C (68.2 F) | -1.3 C (-2.3 F) | 7.2 C (44.9 F) | -2.0 C (-3.6 F) | -1.6 C (-2.9 F) | 30 |
The lists use stations with at least 25 years behind their normal. One station does not stand for the area around it.
Countries
| Country | Stations | Mean vs normal |
|---|---|---|
| Belarus | 9 | +5.3 C (+9.5 F) |
| Ukraine | 22 | +4.2 C (+7.5 F) |
| Estonia | 19 | +3.7 C (+6.7 F) |
| Finland | 121 | +2.7 C (+4.8 F) |
| Bolivia | 5 | +1.9 C (+3.4 F) |
| Mexico | 11 | +1.8 C (+3.2 F) |
| Norway | 72 | +1.7 C (+3.0 F) |
| Romania | 21 | +1.7 C (+3.0 F) |
| Russia | 123 | +1.6 C (+2.9 F) |
| China | 170 | +1.6 C (+2.9 F) |
| Sweden | 180 | +1.6 C (+2.8 F) |
| Germany | 319 | +1.3 C (+2.4 F) |
| Turkey | 9 | +1.3 C (+2.4 F) |
| Netherlands | 31 | +1.1 C (+2.0 F) |
| Indonesia | 12 | +1.1 C (+1.9 F) |
| United States | 4,404 | +1.1 C (+1.9 F) |
| Puerto Rico [United States] | 14 | +1.0 C (+1.8 F) |
| Australia | 393 | +0.9 C (+1.7 F) |
| Austria | 5 | +0.8 C (+1.5 F) |
| Thailand | 31 | +0.6 C (+1.1 F) |
| Namibia | 5 | +0.6 C (+1.1 F) |
| India | 16 | +0.5 C (+0.9 F) |
| Philippines | 5 | +0.4 C (+0.7 F) |
| Greenland [Denmark] | 5 | +0.2 C (+0.3 F) |
| France | 48 | -0.2 C (-0.4 F) |
| Turkmenistan | 17 | -0.2 C (-0.4 F) |
| Spain | 84 | -0.3 C (-0.6 F) |
| United Kingdom | 52 | -0.4 C (-0.7 F) |
| Kyrgyzstan | 5 | -0.4 C (-0.7 F) |
| Switzerland | 8 | -0.4 C (-0.8 F) |
| South Africa | 22 | -0.5 C (-1.0 F) |
| Uzbekistan | 15 | -0.6 C (-1.0 F) |
| Kazakhstan | 25 | -0.8 C (-1.4 F) |
Rain Against Normal
8,052 stations, September 2024| Band | Stations on the map |
|---|---|
| Under 50% of normal | 638 |
| 50 to 90% of normal | 471 |
| 90 to 110% of normal | 182 |
| 110 to 200% of normal | 497 |
| 200% or more of normal | 179 |
| Under 50% | |
|---|---|
| 50 to 90% | |
| 90 to 110% | |
| 110 to 200% | |
| 200% or more |
Of the 8,052 stations with a full month of rain data in September 2024, 34% had less than half their normal September rain and 8% had at least twice their normal; the median station had 79% of its normal. A station month needs 28 days of rain data, because a total from fewer days is too low, and a normal of at least 10 mm.
Wettest Against Normal
| Station | Country | Rain | Normal | Percent of normal | Years of normal |
|---|---|---|---|---|---|
| Doon Doon (McCabes Road) | Australia | 440.4 mm (17.3 in) | 47.0 mm (1.9 in) | 936% | 26 |
| Palm Valley | Australia | 80.5 mm (3.2 in) | 10.7 mm (0.4 in) | 751% | 27 |
| Meerschaum Vale (Jenbetdaph) | Australia | 337.4 mm (13.3 in) | 48.0 mm (1.9 in) | 703% | 30 |
| Rosebank (Upper Coopers Creek) | Australia | 319.2 mm (12.6 in) | 49.7 mm (2.0 in) | 643% | 30 |
| Humpty Doo Collard Road | Australia | 109.6 mm (4.3 in) | 17.1 mm (0.7 in) | 641% | 28 |
| Clunes (Main Rd) | Australia | 267.6 mm (10.5 in) | 42.6 mm (1.7 in) | 629% | 29 |
| Rosebank (Repentance Creek) | Australia | 312.2 mm (12.3 in) | 51.0 mm (2.0 in) | 612% | 30 |
| Giles Meteorological Office | Australia | 65.5 mm (2.6 in) | 10.8 mm (0.4 in) | 604% | 30 |
| Tieyon | Australia | 64.2 mm (2.5 in) | 11.2 mm (0.4 in) | 576% | 26 |
| The Channon | Australia | 211.8 mm (8.3 in) | 39.1 mm (1.5 in) | 542% | 25 |
Driest Against Normal
| Station | Country | Rain | Normal | Percent of normal | Years of normal |
|---|---|---|---|---|---|
| Jasper | United States | 0.0 mm (0.00 in) | 105.3 mm (4.1 in) | 0% | 30 |
| Cedar Rapids Muni AP | United States | 0.0 mm (0.00 in) | 86.1 mm (3.4 in) | 0% | 30 |
| Redwood Falls Muni AP | United States | 0.0 mm (0.00 in) | 72.3 mm (2.8 in) | 0% | 30 |
| Canby | United States | 0.0 mm (0.00 in) | 71.0 mm (2.8 in) | 0% | 30 |
| Big Stone City 2 NW | United States | 0.0 mm (0.00 in) | 64.5 mm (2.5 in) | 0% | 28 |
| Park Creek Ridge | United States | 0.0 mm (0.00 in) | 57.0 mm (2.2 in) | 0% | 29 |
| Ponyri | Russia | 0.0 mm (0.00 in) | 54.9 mm (2.2 in) | 0% | 30 |
| Voronez | Russia | 0.0 mm (0.00 in) | 53.6 mm (2.1 in) | 0% | 28 |
| Ravenna | United States | 0.0 mm (0.00 in) | 53.2 mm (2.1 in) | 0% | 28 |
| Muleshoe Nwr | United States | 0.0 mm (0.00 in) | 52.7 mm (2.1 in) | 0% | 28 |
Weather Records
28,587 set or tied in September 202428,587 weather records were set or tied in September 2024, including 20,374 record highs and 3,009 record lows of maximum and minimum temperature, and 52 all-time records.
| Record high minimum temperature | |
|---|---|
| Record high maximum temperature | |
| Record daily precipitation | |
| Record low minimum temperature | |
| Record low maximum temperature | |
| Record snow depth | |
| Record daily snowfall |
| Daily | |
|---|---|
| Monthly | |
| All-time |
September Against the Ten Years Before
| Year | Record highs, percent of highs and lows |
|---|---|
| 2014 | 62.0% |
| 2015 | 85.3% |
| 2016 | 87.1% |
| 2017 | 70.3% |
| 2018 | 77.4% |
| 2019 | 77.5% |
| 2020 | 62.8% |
| 2021 | 83.3% |
| 2022 | 86.8% |
| 2023 | 92.6% |
| 2024 | 87.8% |
In September 2024, 88% of the daily temperature records were record highs (7.2 to 1 highs to lows), against an average of 79% for September in 2014 to 2023.
The Top 10 Records of September 2024
| Date | Station | Country | Record | Value | Significance |
|---|---|---|---|---|---|
| 2024-09-24 | Napier Downs | Australia | Monthly precipitation | 99.4 mm (3.9 in) | 86 of 100 (Exceptional) |
| 2024-09-05 | Nagold | Germany | Monthly precipitation | 65.2 mm (2.6 in) | 82 of 100 (Exceptional) |
| 2024-09-14 | Selma | United States | Daily precipitation | 154.4 mm (6.1 in) | 80 of 100 (Exceptional) |
| 2024-09-19 | Ft Benton | United States | Daily precipitation | 39.9 mm (1.6 in) | 80 of 100 (Exceptional) |
| 2024-09-26 | Wytheville | United States | Daily precipitation | 88.1 mm (3.5 in) | 80 of 100 (Exceptional) |
| 2024-09-28 | Banner Elk | United States | Daily precipitation | 132.1 mm (5.2 in) | 80 of 100 (Exceptional) |
| 2024-09-24 | Bryah | Australia | Daily precipitation | 25.2 mm (1.0 in) | 79 of 100 (Major) |
| 2024-09-14 | Kisinev | Moldova | Daily precipitation | 69.1 mm (2.7 in) | 78 of 100 (Major) |
| 2024-09-19 | Chinook | United States | Daily precipitation | 61.0 mm (2.4 in) | 78 of 100 (Major) |
| 2024-09-23 | Ruby Plains | Australia | Monthly precipitation | 51.0 mm (2.0 in) | 78 of 100 (Major) |
Countries With the Most Records
| Country | Records | Highs | Lows |
|---|---|---|---|
| United States | 12,344 | 8,754 | 1,704 |
| Germany | 2,325 | 1,681 | 223 |
| Australia | 2,271 | 857 | 296 |
| Russia | 1,279 | 1,037 | 113 |
| Finland | 1,269 | 1,147 | 5 |
| China | 1,190 | 1,040 | 27 |
| Sweden | 1,096 | 808 | 11 |
| Japan | 675 | 650 | 0 |
| Norway | 632 | 492 | 19 |
| Netherlands | 454 | 119 | 28 |
| India | 321 | 259 | 23 |
| Indonesia | 293 | 281 | 12 |
| United Kingdom | 243 | 106 | 72 |
| Thailand | 240 | 201 | 11 |
| Ukraine | 230 | 216 | 0 |
Events and Storms
20 named storms had a best track position in September 2024; 11 peaked at 64 kt (119 km/h, 74 mph) or more and 5 at 96 kt (178 km/h, 110 mph) or more over their lifetime.
| Storm | Basin | Lifetime peak wind | Category at peak |
|---|---|---|---|
| Ancha | South-West Indian | 50 kt (93 km/h, 58 mph) | Tropical storm |
| Kirk | North Atlantic | 130 kt (241 km/h, 150 mph) | Category 4 |
| Joyce | North Atlantic | 45 kt (83 km/h, 52 mph) | Tropical storm |
| Krathon | Western North Pacific | 133 kt (246 km/h, 153 mph) | Category 4 |
| Jebi | Western North Pacific | 70 kt (130 km/h, 81 mph) | Category 1 |
| Isaac | North Atlantic | 90 kt (167 km/h, 104 mph) | Category 2 |
| Helene | North Atlantic | 120 kt (222 km/h, 138 mph) | Category 4 |
| Cimaron | Western North Pacific | 35 kt (65 km/h, 40 mph) | Tropical storm |
| John | Eastern North Pacific | 105 kt (194 km/h, 121 mph) | Category 3 |
| Soulik | Western North Pacific | 35 kt (65 km/h, 40 mph) | Tropical storm |
| Pulasan | Western North Pacific | 53 kt (98 km/h, 61 mph) | Tropical storm |
| Ileana | Eastern North Pacific | 45 kt (83 km/h, 52 mph) | Tropical storm |
| Gordon | North Atlantic | 40 kt (74 km/h, 46 mph) | Tropical storm |
| Francine | North Atlantic | 90 kt (167 km/h, 104 mph) | Category 2 |
| Bebinca | Western North Pacific | 78 kt (144 km/h, 90 mph) | Category 1 |
| Leepi | Western North Pacific | 40 kt (74 km/h, 46 mph) | Tropical storm |
| Yagi | Western North Pacific | 140 kt (259 km/h, 161 mph) | Category 5 |
| Asna | North Indian | 40 kt (74 km/h, 46 mph) | Tropical storm |
| Hone | Eastern North Pacific | 75 kt (139 km/h, 86 mph) | Category 1 |
| Shanshan | Western North Pacific | 95 kt (176 km/h, 109 mph) | Category 2 |
September 2024 in Context
These values come from other sources and the site's own analysis pages. They are context for September 2024; this page does not say that any of them caused the temperatures or records above.
How These Numbers Are Made
Each station's mean daily maximum and minimum temperature for September 2024 is compared with its own mean for September in 1991 to 2020, from months with at least 20 days of both. A station needs 20 such years for a normal. The mean is the average of the two differences. A station month more than 15 C (27 F) from its normal in either element is treated as a data error and left out.
For the world and each continent, stations are averaged within 5 degree grid cells and the cells are averaged weighted by the cosine of their latitude, so dense networks do not outweigh sparse ones. A continent uses the stations of its own countries. A year gets a value and a rank only when its cells hold at least 50% of the weight of all the cells that have ever had data for September, the rule of the climate pages. This is a station based view: places without stations are not covered, and it is not a gridded temperature analysis.
Records are the site's public ledger: one record per observation, set or tied, at its broadest timescale. The ten year comparison uses daily temperature records only, ties excluded. The numbers and sentences on this page are generated by code from the station data; none of them is typed in by hand.
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Source: NOAA National Centers for Environmental Information, Global Historical Climatology Network Daily (GHCN-Daily). Records are computed by World Extreme Weather Monitor and are not official NOAA products. (US Government open data (NOAA NCEI)) Source: International Best Track Archive for Climate Stewardship (IBTrACS) v04r01, NOAA National Centers for Environmental Information, doi:10.25921/82ty-9e16. Some agency values come from third parties such as JMA, IMD and BoM. (NOAA NCEI terms (citation requested)) Source: NOAA Climate Prediction Center, Oceanic Nino Index (ONI) and Relative Oceanic Nino Index (RONI). Episodes and strength classes are computed by World Extreme Weather Monitor and are not NOAA products. (US Government work, public domain (NWS disclaimer)) Source: Fetterer, F., Knowles, K., Meier, W. N., Savoie, M., Windnagel, A. K. and Stafford, T. (2025). Sea Ice Index, Version 4 (G02135). Boulder, Colorado USA. National Snow and Ice Data Center. doi:10.7265/a98x-0f50. Yearly extremes, ranks, trends and the climatology are computed by World Extreme Weather Monitor from the daily extent files and are not NSIDC products. (NSIDC data use and citation policy (public domain government funded data, citation required)) Source: NOAA Global Monitoring Laboratory, Earth System Research Laboratories (gml.noaa.gov/ccgg/trends). Mauna Loa CO2 data are from NOAA and Scripps (before 1974 the monthly values come from the Scripps Institution of Oceanography). The global means of CO2, methane and nitrous oxide are from the NOAA GML cooperative air sampling network (methane and nitrous oxide: Lan, Thoning and Dlugokencky, doi:10.15138/P8XG-AA10). (US Government open data (NOAA GML, citation requested)) Data as of 2026-11-09. Temperatures against normal, ranks and records are computed by this site from station data and are not official.