May 2023 has been somewhat of a strange month. An odd pattern with a distinct tale of two halves precip-wise with wet start and dry end. A slow and gradual warming trend through the final week.

Maximum UK temperatures have been mediocre to say the least this month. According to Syran Bruan, with a UK maximum failing to reach 22C or higher through May 14th, you have to go all the way back to 1985 to find a lower UK annual maximum through mid-May.

After Ireland beat the UK to the first 21C by a mere 24 hours back on April 16th, it’s only managed to stutter beyond the figure of 21.3C by a measly 0.4C on May 25th, over 5 WEEKS later.

Unusually late first 25s!

As we wave goodbye to May and spring 2023, the thermometer has finally broken the 25C barrier, the latest such reading for the UK since 2013. Paris observed it’s latest 25C in 40 years and even typical warm spots such as Malta saw a very late first 25C. Iberia started May hot and dry but ends with torrential rains and cool temps.

While warmer than average, it’s not been a standout warm month nor has it been particularly cold either for UK and Ireland, aided by mild, often cloudy nights.

Meanwhile the bulk of mainland Europe has been cool.

WARMER & COLDER MAY’S IN RECENT YEARS

2012

May 2012 was extreme with coldest opening 15 days for the UK in an astonishing 300 years followed by hottest May days on record.

With a maximum of 30.9C recorded at Inverailort, Highland on 25 May, Scotland set a new May record after witnessing it’s warmest March day (23.6C) on record. Glasgow saw it’s warmest May day on record with a high of 27.1C.

2016

Temperatures reached 27.7C at Plockton, W Highland, 27C in London.

2017

Lossiemouth, Moray tops 29.4C.

2018

This month featured the warmest early May bank holiday since it’s introduction back in 1978 with a high of 28.7C at Northolt, Greater London on the 7th. The UK minimum was -4.6C at Aboyne, Aberdeenshire on the 1st.

2020

1C above average. A UK minimum of -6.6C was recorded at Kinbrace, Sutherland (coldest UK May night since 1997) on the 3rd while a UK maximum of 28.3C was recorded at Cromdale, Moray on the 29th.

A low of -6.1C recorded at Katesbridge, Co Down (coldest May night for NI since 1982) on the 14th fell just 0.4C off the lowest May temperature ever recorded in Northern Ireland.

2021

The month began very unsettled and unseasonably cold with notably deep lows. An overall 1.3C below the UK average.

A UK minimum of -6.1C was recorded at Harmon, Powys on the 2nd. Provisionally the 4th wettest May since 1862 with 171% of normal. A wind gust of 93 mph was recorded at the Needles Old Battery (Isle of Wight) on the 3rd. 1cm snow depth at Achiltibuie, Ross-shire on the 5th.

Despite being a cold month, Kinlochewe, Ross-shire recorded a UK maximum of 25.1C on the 31st.

2022

1.2C above the UK average with a maximum of 27.5C recorded at London’s Heathrow Airport. Minimum -1.7C recorded at Altnaharra, Sutherland.

Warm North, Cool South to End Spring!

Mean ridge position during May hence drier than March, April.

Position of core slightly west of Scotland has led to less warmth within the column (ocean modified), therefore limiting heating potential to only the low 20s even for typically warmer inland areas. Winds have also been a factor in restricting warmth.

The month is ending with the high centred almost directly over Scotland hence temperatures rising into the mid to upper 20s. This comes at a price for folks further south thanks to strengthening ENE winds, strongest for East Anglia and South where highs will be below average.

Will June be flaming?

For the month as a whole, I suspect in short, a ridge over trough situation. Warmest, driest across Northern Europe including Scotland, Northern Ireland and Scandinavia. Much more unsettled with frequent thunderstorm and flood threat continuing across the Med/S Europe.

Week 2 of June looks to see the mean ridge position back away from Scotland towards Greenland providing a limit on warmth but then move back overhead increasing warmth across Northern UK/Ireland week 2 into 3 but NE winds blowing around the HP will keep the bulk of England and Wales fresher, even chilly on the coasts, possibly even inland.

As the month progresses from first to second half, the high remains across the north but could slide east more towards Scandinavia allowing potentially warmer temps to build all the while a trough could begin to edge closer to the Southern UK/Ireland increasing the threat of showers and thunderstorms. Increase in humidity too.

I suspect the majority of the UK and Ireland as well as even N France will be largely dry through the first 10-15 days of the month with increased chance of showers and thunderstorms lifting northwards through the second half.

Heating potential looks to remain rather limited through the first half of June due to ridging slipping away but it’s possible return beyond week 2 should see warmer days and the potential of upper 20s to near 30, especially for Scotland and Northern Ireland.

Abnormally warm SST’s in both Atlantic and western Med could feed heavy rains over Iberia and S Europe too.

Latest CFSv2 weeklies

500mb geoptential anomaly

Precip anomaly

Temp anomaly

OVERALL, JUNE FOR THE UK & IRELAND LOOKS TO BE NEAR AVERAGE FOR TEMPERATURE… POSSIBLY BELOW IN SOUTH AND ABOVE IN NORTH… DRIER THAN NORMAL OVERALL BUT WITH POSSIBLY WETTER THAN NORMAL SOUTH, DRIER NORTH!

FEATURED IMAGE: Syran Bruan

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