DULL, DRY JULY, WARMER THAN AVERAGE

Armagh Observatory reports that apart from the exceptionally dull July 2020 this July at Armagh had the fewest hours of strong sunshine for 29 years.  It was also the driest at Armagh for 22 years and more than 1 degree Celsius warmer than the most recent 30-year July average.

Total precipitation was 23.2 mm (0.91 inches) including six trace values, that is, 22.9 mm (0.90 inches) if trace values are ignored. This is approximately 32% of the 183-year long-term (1838-2020) average July precipitation at Armagh (73.4 mm) and 34% of the most recent (1991-2020) 30-year July average (69.0 mm), making this July the driest at Armagh since July 2000 (13.3 mm), and the twelfth-driest July at Armagh in an instrumental record beginning in 1838.

The wettest day was the 24th with 10.1 mm (0.40 inches) of precipitation, associated with the same weather system that brought torrential rain and floods to parts of Co. Tyrone and north-west Ulster. The second-wettest day was the 29th with just 3.8 mm (0.15 inches). There was no thunder or lightning at Armagh this month, but the observer noticed a squabble of about a dozen noisy gulls in an area adjacent to the Astropark around the time observations were being taken on the 25th.

The mean temperature (the monthly average of the daily maximum and minimum temperatures) was 16.85 degrees Celsius (62.3 Fahrenheit).  This is approximately 2.0 C warmer than the 225-year long-term (1796-2020) average July temperature at Armagh (14.87 C) and 1.1 C warmer than the most recent (1991-2020) 30-year July average (15.72 C).  This was the thirteenth-warmest July at Armagh since daily temperature records began at the Observatory around 1795.

Although much warmer than the most recent 30-year July average temperature at Armagh, this July was still more than 1-degree Celsius cooler than the record-breaking July 2021, perhaps because of its predominantly cloudy skies and lack of strong sunshine compared to last July.  The month was also noteworthy for a high average monthly minimum temperature (12.8 C), almost the same as during July 2021 (12.9 C).  The average monthly maximum (20.9 C), however, was almost 2 degrees Celsius less than the corresponding figure last year (22.9 C).

The 8th and 9th recorded unusually high atmospheric pressures for July, more than 1034 mbar reduced to mean sea level, owing to the development of a large area of high pressure over the Atlantic ocean to the south-west of Ireland.  These were the highest July atmospheric pressures observed at Armagh for nine years, that is, since the 7th and 8th July 2013 (approximately 1035 and 1036 mbar respectively).

Most people will remember this July as the one when the highest daily maximum temperature in the UK exceeded 40 C for the first time, on 19th July 2022, with accompanying heat stress.  In England, the new record was 40.3 C, and in Wales and Scotland 37.1 C and 35.1 C respectively. Further north and west, the highest temperatures were lower, and in Northern Ireland the highest maximum temperature confirmed by the UK Meteorological Office was 31.2 C at Derrylin, Co. Fermanagh, on 18th July 2022.  This was just 0.1 C below the official Northern Ireland temperature record (31.3 C), recorded on 22nd July 2021 at Castlederg, Co. Tyrone.

The warmest day or the highest maximum air temperature at Armagh this month was also 31.2 C on the 18th, equalling that at Derrylin and the second-warmest day on record at Armagh.  This highest daily maximum, the warmest day of the year at Armagh so far, was preceded by 27.8 C on the 17th.  However, the two days did not count as a heat wave as the threshold for such a weather event (25.0 C in Northern Ireland) was not equalled or surpassed for at least three days in a row.   By contrast, the coolest day or lowest maximum air temperature this month was 16.2 C on the 27th, followed by 17.0 C on the 4th.

The warmest night or highest minimum air temperature was 17.8 C on the 19th, followed by 17.1 C on the 12th.  The coolest night or lowest minimum air temperature was 9.2 C on the 27th followed by 9.5 C on the 29th.  There were no air frosts or ground frosts this month, although the 16th recorded a grass-minimum temperature close to zero (0.3 C).

July 2022 was a dull month, often cloudy, producing just 96.9 recorded hours of strong sunshine.  This is approximately 71% of the 140-year long-term (1881-2020) July average (135.6 hours) at Armagh and 72% of the most recent (1991-2020) 30-year average (134.8 hours).   Apart from the exceptionally dull July 2020 (81.5 hours of strong sunshine), this was the dullest July at Armagh for 29 years, that is, since July 1993 (92.6 hours).

The sunniest day by a wide margin was the 18th with 12.9 hours of strong sunshine, followed by 7.0 hours on the 2nd and 6.3 hours on the 13th.

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, College Hill, Armagh, BT61 9DG

Tel: 028-3752-2928

E-mail: mark.bailey@armagh.ac.uk


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