June 2026 has started off with changeable west to south-westerlies, although temperatures have widely been a little above the 1991-2020 long-term normal, chiefly due to high night time minimum temperatures. There was a strong signal for a build of high pressure from the south around 10-15 June, but this has receded during the past week. It still looks probable that high pressure will build to the south and south-east of Britain during that period, but it looks probable that Britain will remain in a predominantly west to south-westerly flow on its northern flank. The ECMWF 42-day outlook still suggests that high pressure will build from the south eventually, but has delayed it to around 20 June rather than 10-15 June.
This means that around the middle part of this June, we can expect more of a northwest-southeast split pattern to develop, with south-eastern Britain becoming warmer and drier, and probably sunnier, while the north-west will often be wet and cloudy. The prolonging of the spell of changeable westerly types means that there is a reduced likelihood of June as a whole ending up on the dry side. Some southern and western areas have already had enough rain to ensure that it would have to be very dry for the rest of June for rainfall not to end up above average.
It will probably still end up as a warm June overall. Even the current wet spell is still coming out slightly warmer than average in most regions, and it will probably become warmer relative to average later in the month as high pressure builds to the south and east and we see greater potential for hot southerlies to develop at times. Also there is still potential for a relatively sustained spell of high pressure after 20 June.
We are entering a strong El Nino, and there are still parallels with 1966 and 1982, both of which contained Junes that were warm but wet. The first half of June 1997 was also warm and wet, although it turned cold and wet later in the month and so the month's mean temperature was slightly below normal. It is currently looking unlikely that June 2026 will go the way of June 1997, as there remains a strong signal for high pressure to build to the south-east later in the month, the opposite of what happened in June 1997. However, if this high pressure build proves less strong than is currently modelled, we could end up with a warm and wet June that stays wet for a large part of the month, as happened in both 1966 and 1982.
El Nino typically results in a temporary rise in global temperatures, sometimes by as much as 0.2-0.3°C. In a stable climate this would be a part of natural fluctuations either side of a stable long-term average. But as the climate has been warming since around 1980, since then, El Nino events have tended to repeatedly set new benchmarks for record high global temperatures. Following the El Nino, global temperatures typically fall, but to higher levels than they were at prior to the previous El Nino, typically running third or fourth warmest on record before we get the next El Nino.
Averaged globally, daily global temperatures (which are updated about a week in arrears on Climate Reanalyzer) are not yet responding strongly to the onset of the El Nino. Global temperatures have crept closer to the record highs set in 2023 and 2024, but are still mostly behind those two years, and ranking third warmest on record. However, sea surface temperatures are already trending towards being record warm (currently approximately tied with 2024).
It will be interesting to see how global temperatures respond to the El Nino. Previously, there has tended to be a lagged effect, with global temperatures typically becoming record warm during the back end of an El Nino event. Sometimes when an El Nino sets in around the middle of a calendar year, as looks likely this year, global temperatures rise enough towards the end of the year to make the year record warm overall, but it would require a substantial rise this year to make it the warmest year on record globally. However, in 2023 we saw an unusually early response to the El Nino, when global temperatures soared to record high levels just as the El Nino was beginning. There is still time for this to happen in 2026, but time is running out.
However, I will be very surprised if 2027 isn't another record warm year globally, as the late 2026 El Nino is forecast to be very strong. Because 2023/24 was such an unusual El Nino in terms of its strong impact on global temperature, it may well be that 2027 doesn't smash records to as large an extent as those two years, but a record warm year globally by a margin of about 0.1°C, maybe as high as 0.2°C, looks a plausible outcome.
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