With high-pressure dominating, the past day or two have delivered the first real hint of spring warmth for many.
Under Wednesday’s clear skies, west Wales and southeast England rose above 20°C for the first time this year, with Gogerddan recording 20.9°C and Northolt seeing 20.2°C.
This lift in temperature comes not only from March sunshine but also from the influence of east to southeasterly winds descending from higher ground, a Foehn-type effect that can add a subtle but significant boost.
It’s the kind of pattern that often marks the earliest arrival of our warmest early-spring days, setting the stage for a closer look at when the UK has historically first reached 20°C, 21°C and 22°C, according to Met Office station data.
The earliest 20°C of each year
The first time the UK reaches 20°C can sometimes be remarkably early. According to station data, last year’s earliest 20°C reading fell on 20 March 2025, marking an unusually early burst of warmth and signalling a rapid transition into springlike conditions. This year, some areas in the UK felt 20°C on 18 March,
Other recent years highlight both how early, and how varied, this milestone can be:
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2024: 6 April
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2023: 17 April
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2022: 19 March
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2021: 29 March
Looking back, 20°C days appear regularly in late March, but there have been even earlier exceptions. The standout example is 25 February 2019, when an extraordinary late-winter warm spell pushed temperatures above 20°C, the earliest occurrence of this figure according to Met Office station data.
READ MORE: A week of warm spring weather with sunny spells
This demonstrates not only the sensitivity of spring temperatures to weather patterns but also how changes in airflow can bring unseasonably warm conditions well ahead of schedule.
The earliest 21°C of each year
The threshold of 21°C tends to follow closely behind the first 20°C day, though it still shows considerable variation. In a particularly notable example, the earliest 21°C reading occurred on 26 February 2019, occurring a day after 20°C was first reached for the first time that year.
Recent years show a more staggered pattern:
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2024: 12 April
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2023: 17 April
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2022: 15 April
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2021: 30 March
These dates show how quickly temperatures can climb once the sun becomes strong enough in late March and early April. A subtle shift in wind direction may make the difference between a high-teens day and one that reaches the low twenties.
The earliest 22°C of each year
Reaching 22°C typically requires a more settled, warmer setup, yet in some years it arrives surprisingly early. The earliest 22°C in the most recent data appears on 24 March 2012, marking a striking early-spring warm spell.
But the timing varies widely:
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2024: 1 May
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2023: 7 May
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2022: 15 April
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2021: 30 March
These early 22°C days underline how responsive spring temperatures are to atmospheric shifts, especially when high pressure and sunshine combine with favourable airflow.
What drives such early heat?
When the UK reaches temperatures in the low twenties unusually early, it is almost always due to a combination of:
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Strong, persistent high-pressure systems: Clear skies allow rapid daytime warming.
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Dry air masses: Dry air heats more efficiently than moist air.
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Foehn-type effects: Air descending from higher ground warms significantly, giving western regions a notable boost.
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Continental or southerly airflow: These bring warmer air masses into the UK.
Forecasters emphasise that these setups also come with large diurnal ranges, warm days paired with chilly nights, as clear skies allow heat to escape quickly after sunset.
READ MORE: March weather extremes: a closer look at March's current weather records
Why these early milestones matter
Tracking the earliest arrival of 20°C, 21°C and 22°C can offer important scientific context, though it’s part of a wider way of measuring weather in the UK. Early warmth can influence several areas:
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Nature and ecology: Early budding, flowering and insect activity.
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Pollen season: Higher temperatures can accelerate the onset of tree and grass pollen seasons.
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Public health and comfort: Heat early in the season can feel more pronounced before people adjust.
These early warm spells are also part of a long-term record that helps meteorologists compare seasonal progression year-to-year, spotting unusual patterns or emerging trends.
A spring of variability
Taken together, the earliest dates for reaching these temperature thresholds highlight a key feature of UK spring weather: variability. While some years see an early surge of warmth driven by favourable atmospheric conditions, others wait until April or May before tipping into the low twenties. The sequence from 20°C to 22°C can unfold over days, or take several weeks.
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