The month was outstanding for its dryness, the warmth by day, and for ending with one of the warmest and sunniest weeks since 1950.
High pressure and NE winds dominated from Friday the 1st to Wednesday the 13th, which were rainless days and mostly warm. The max reached 78F (25.6C) on the 3rd, which was 11F above the average, while the min of 56F (13.4C) on the 10th was 8F above average. There were, however, some cooler periods with the max down to 63F (17C) on the 5th, which was the coolest day of the month The min of 44F (6.4C) on the 13th gave a very cold night for mid-June with the min 6F below average.
Westerly winds briefly returned as several Lows moved north-eastwards off Scotland from the 14th to 17th. The first of these, Storm Hector, gave damaging gales over Scotland and the North with some heavy rain. Hector was not significant in Mid-Sussex, but its cold front gave 0.3mm of rain on the 14th, and further weak fronts gave 0.2mm on the 16th and 0.1mm on the 17th.This was the only rainfall of the month, giving a total of 0.6mm, making it easily the driest June since 1950. In the period from January 1950 to June 2018, only one other month has been as dry. This was August 1995, which had 0.5mm of rain.
The pressure rose again and the 13 days from Monday 18th to Saturday 30th were rainless.
With a High to the west of Ireland, northerly winds kept the max only a little above average. Nights now became cool with the min down to 45F (7.4C) on the 22nd and, under clear skies, remained so for the rest of the month.
From the 24th, with the High now over the North Sea, easterly winds gave heat wave conditions by day. It was exceptionally sunny, with 99 hours of sunshine in the last week. The max increased from 76F on the 23rd to 84F (28.7C) on the 30th, which was the warmest day of the month. With a brisk breeze by day, low humidity and cool nights, the heat was never oppressive.
The temperature profile for the month was unusual. The max had been below average on only five days but well above it on 12 days. This made the mean max the third highest in June since 1950.
The mean min was completely different with the run of cold nights from the 21st leading to the mean min being only just over 1F above average. Despite this, the mean temperature for the month still made it the third warmest June since 1950 after 1976 and 2017.
Sunshine was below average in the first half of the month, but the second half was very sunny, making the month’s total 247 hours, which was 17% above average.