MARCH 2025 DRIER AND SUNNIER THAN AVERAGE, AND MUCH WARMER
Armagh Observatory, 4th April 2025: Armagh Observatory reports that March 2025 was drier and sunnier than average, and much warmer. This was driest March at Armagh for 13 years, continuing a series in which each month since last April has been drier than average. It was also the sunniest for three years and the warmest for 13 years. The mean temperature was 8.3 degrees Celsius (46.9 Fahrenheit). This was approximately 2.5 C warmer than the 225-year long-term (1796-2020) average March temperature at Armagh (5.82 C) and 1.5 C warmer than the most recent (1991-2020) 30-year March average (6.75 C). This was the eighth warmest March on record at Armagh and the warmest since March 2012 (mean temperature 8.9 C). Six of the last seven years have had average March temperatures greater than the most recent 30-year average.
A comparison with the (1961-1990) 30-year March average (6.02 C) suggests that mean March temperatures at Armagh are increasing at a rate of approximately 0.24 C per decade. The month was also dominated by relatively high atmospheric pressure. This led to an average barometric pressure at Armagh reduced to mean sea level of approximately 1018 mbar, the highest average March pressure at Armagh for three years. This was approximately 3.8 mbar higher than the most recent (1991-2020) 30-year March average pressure (1014 mbar).
High pressure often leads to clearer-than-average skies, and to a tendency for days to be sunnier and warmer than average. Conversely, clear skies can often lead to relatively low nighttime temperatures.
This month, the average daily maximum temperature was 12.6 C, approximately 2.2 C warmer than the corresponding most recent (1991-2020) 30-year March average (10.4 C). This was the fourth warmest such average on record, shared with March 1929, 1938, and 1961, and the highest such average at Armagh since 2022 (12.8 C). In contrast, the monthly mean of the daily minimum temperatures (4.0 C) was just 0.9 C above the corresponding most recent (1991-2020) 30-year average (3.1 C), showing that, on average, the higher-than-average warmth of the days was greater than that of the nights, consistent with the suggested effect of the month’s relatively high pressure. The highest air temperature, or warmest day, this month was 18.2 C on the 31st followed by 16.2 C, which occurred on three days (the 8th, 9th, and 30th). This was the warmest day of the year at Armagh up to the end of March, but it was not an exceptionally warm day for late March. For comparison, the warmest March day on record at Armagh is 21.8 C on 29 March 1965. The lowest maximum air temperature, or coolest day, was 7.8 C on St Patrick’s day, followed by 9.0 C on the 11th and 9.1 C on the 1st. At Armagh, the maximum temperature on St Patrick’s day was much cooler than the most recent (1991-2020) 30-year average for that day (10.7 C), and although dry there was no sunshine. The highest minimum air temperature, usually the warmest night, was 10.3 C on the 31st, followed by 9.4 C on the 27th and 8.6 C on the 22nd. The lowest minimum air temperature or coolest night was -2.7 C on the 19th, followed by -2.2 C on the 15th, and -1.1 C on the 13th.
There were 16 nights with ground frost (minimum grass temperatures less than or equal to zero Celsius), of which the three coldest were -9.5 C on the 15th, -8.3 C on the 19th, and -7.8 C on the 18th. There were five nights with air frost, the three previously mentioned and the 20th (-0.9 C) and 11th (-0.4 C).
The month of March, the first of the meteorological spring, is usually one of the drier months of the year. Considering that the two previous Marches were unseasonably wet, it is perhaps unsurprising that March 2025 was much drier than average. It was, in fact, the eighth driest March on record at Armagh and the driest since March 2012 (16.9 mm of precipitation including 6 trace values). Total precipitation was 17.85 mm including five trace values, or 17.6 mm if trace values are ignored. This is approximately 32% of the 183-year long-term (1838-2020) average March precipitation at Armagh (55.7 mm) and 30% of the most recent (1991-2020) 30-year average (59.7 mm), continuing an interesting trend in which every month since last April has been drier than average. So far, April 2025 is already shaping up to be relatively dry.
The wettest day was the 28th, with 5.6 mm of rainfall, followed by 5.5 mm on the 22nd and 2.2 mm on the 27th. There was no snow this month, but a heavy rain shower with hail occurred late morning on the 28th. A rainbow was seen late afternoon the same day.
Approximately 50 gulls were observed circling around the met station on the morning of the 5th. This was a dull but otherwise dry day with a cool, fresh breeze.
With a total of 119.7 hours of strong sunshine, this March was sunnier than average, approximately 17% more than the 140-year long-term (1881-2020) average March at Armagh and 16% more than the most recent (1991-2020) 30-year average (103.0 hours). This was the sunniest March at Armagh since the record-breaking sunny March 2022 (188.4 hours of strong sunshine). The sunniest days were the 9th and 30th (both 9.4 hours of strong sunshine), followed by the 24th with 9.1 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
College Hill
Armagh
BT61 9DG