Mild, dry September and sunnier than average.
Armagh Observatory reports that September 2020 was warmer and drier than average and with slightly more than average sunshine. This was the sunniest September at Armagh for five years.
The mean temperature was nearly 13.7 degrees Celsius (56.6 Fahrenheit), which is approximately 1.2 C warmer than the long-term (1796-2010) average September temperature at Armagh and 0.4 C warmer than the most recent (1981-2010) 30-year September average.
The warmest day (highest maximum air temperature) was 23.9 C (75.0 F) on the 15th, which occurred at the end of a short warm spell that also saw 22.6 C on the 14th and 22.5 C on the 13th. The 15th was the warmest September day at Armagh for 29 years, that is, since 24.8 C was recorded on 1991 September 4. The coldest day (lowest maximum air temperature) was 12.9 C on the 24th followed by 13.7 C on the 25th.
The highest minimum air temperature was 15.1 C recorded on the 8th, followed by 14.7 C on the 15th and 14.6 C on the 16th. The lowest minimum air temperature was 1.1 C, recorded on the 27th, preceded by 2.1 C on the 26th and 2.5 C on the 25th. This coldest night was the coldest September night at Armagh since 2007, coincidentally also recorded on September 27 (0.7 C). There were eight ground frosts (grass minimum temperature less than or equal to zero Celsius), the coldest three of which were -5.9 C on the 27th, -4.3 C on the 26th and -3.7 C on the 25th.
Total September precipitation was 49.2 mm (1.94 inches), including 4 trace values (i.e. 49.0 mm if trace values are ignored). This is approximately 71% of the average September rainfall at Armagh. The wettest day was the 29th with 9.3 mm (0.37 inches) of rainfall, preceded by 9.2 mm on the 1st. A double rainbow was seen late afternoon on the 24th.
A total of 120.0 hours of strong sunshine were recorded during the month, which is nearly 7% more than the long-term (1881-2010) average number of hours of strong September sunshine at Armagh and approximately 5% more than the most recent (1981-2010) 30-year average. This was the sunniest September at Armagh for five years. The sunniest day was the 19th with 10.2 hours of strong sunshine, followed by the 26th with 8.6 hours.
These data refer to observations at Armagh Observatory, which has been recording the weather at Armagh since 1795.
For further information, please contact:
Professor Mark E. Bailey Emeritus Director of Armagh Observatory
Armagh Observatory and Planetarium