July 1969 was noteworthy as the warmest month in that whole decade. Why mention that now? Because its weather was so similar to July 2020, which few will be considering in any way special, having only a scattering of hot days. So much has our climate changed since the 1960s.

July this year began where June left off, showery with sunny intervals and temperatures down on what we might expect. A deep depression to the north of Scotland on July 4 placed us under a strong airflow from the south-west, giving us a dull, humid but very warm day. The next week saw a series of weak weather fronts crossing our region, with winds fluctuating between south-west and north-west. Temperatures were about average, with not a lot of sun and almost no rain. High air pressure at last moved in from the west on July 11, giving a clear, sunny day after a chilly start, the overnight minimum being only 7C (45F). Sunday, July 12, then gave us our first proper summer’s day for nearly three weeks, very sunny with a temperature in Wellington of 24.5C (76F).

Mid-month, there was another brief unsettled spell, but rain that was forecast failed to materialise, the ground by this time being very dry. A high pressure ridge then introduced warmer air once more, the mercury reaching 25.5C (78F) in Wellington on July 17, before another slow-moving front gave 6mm (0.24 inches) of rain overnight on July 18/19. A light, cool, breeze from the north then made July 20 a day of exceptionally clear air and prolonged sunshine.

As the wind then backed towards a warmer point, there was a significant rise in temperature by day and night. 26C (79F) on July 22 was our highest reading for four weeks but with this warmth came moisture. After two rather cloudy days with a little drizzle at times, and then a very warm night, July 25 was dull from the start. During the afternoon, two short spells of intense rainfall with thunder crossed our area, giving 17mm (0.67 inches) of rain in Wellington, and doubling the month’s running total at a stroke.

After a couple of days with showers and sunny spells, a ridge of high pressure gave a fine, sunny end to the month. July 30 was an almost windless day with wall-to-wall sunshine but the heat peaked on the last day. With a light southerly breeze that had originated over the Mediterranean, the temperature in Wellington soared to 31C (88F) well before lunchtime. We have had only ten hotter July days in the past 45 years. Fortunately, perhaps, a veil of high cloud made the afternoon more bearable, in advance of another very warm, dull night.

Overall, the month turned out slightly sunnier than normal, and relatively dry with a total of 40mm (1.6 inches) of rain in Wellington, about 60 per cent of average. The mean temperature of 16.9C (62.4F) was exactly average for the current official reference period (1981–2010). As in July 1969, it was mostly dry until near the end. But there was no repeat of July 28, 1969, which saw rainfall totals widely well in excess of 100mm (4 inches) in 24 hours – the last time our region experienced such a deluge.

Simon Ratsey

WWN weather correspondent