This week sees an end to the hot, dry and sunny weather as temperatures return to closer to average, along with showers and spells of rain.
The high pressure that brought the prolonged spell of hot and dry weather has been replaced by an area of low pressure to the east of Ireland, introducing a cooler mainly north-westerly airflow and marking an end to the heatwave.
Surface Pressure Analysis chart at 00UTC 26th July 2021
Met Éireann meteorologist Liz Walsh said, “Last week we were keeping our eye on the high temperatures, but this week, now that the heatwave has ended we’re keeping our eye on the potential for heavy showers and thunderstorms, which could lead to some surface flooding in places.
“We have issued a Yellow Rain and Thunderstorm warning for today (Monday 26th) and an Advisory for thundery downpours over the next few days. Today and Wednesday are currently expected to see the highest chance of thunderstorm activity, with the potential for 50mm falling in just a few hours. We’re encouraging people to keep an eye on Met Éireann forecasts and warnings this week as well as checking our radar to keep an eye on heavy shower and thunderstorm development.”
⚠️Yellow rain & thunder warning issued ⚠️
After a long spell of dry weather, rain returns today with heavy showers & thunderstorms possibly leading to surface flooding in a few areas.
See all active warnings here ➡️https://t.co/Xg3aMJlyuS pic.twitter.com/BENN1uYOtf
— Met Éireann (@MetEireann) July 26, 2021
The heatwave is expected to end today (Monday 26th) as temperatures will likely not break the 25°C threshold anywhere in Ireland. Heatwave criteria was met at fourteen stations across Ireland during the hot spell, with the longest number of consecutive summer days (>25°C) recorded at six stations lasting 10 days. The highest temperature of the year was also recorded during this heatwave, with 30.8°C at Mount Dillon, Roscommon (11.1°C above its July normal) on Wednesday 21st July. Two tropical nights in a row were also recorded during the heatwave, with the temperatures at Valentia Observatory not falling below 20°C on Wednesday 21st and Thursday 22nd nights. Tropical nights are very rare in Ireland with around seven being recorded since digital records began in 1942.
Why has the heatwave ended?
High pressure has been replaced by low pressure this week and we are now on the cold side of the Jet Stream, which has dipped to the south of Ireland, bringing more of an Atlantic influence to our weather this week. The upper levels of the atmosphere are also cold and dominated by low pressure, meaning our weather looks set to be rather unsettled at times this week with spells of rain, showers and the potential for thundery downpours.
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