After falling day by day for six days, the maximum yesterday rose well above the mean to a peak of 26.5C, which is 4C above the long-term mean. We enjoyed 5.33 hours of strong sunshine with the UV level still in the ‘very high’ category. The past night was a little cooler with a minimum of 11.1C around dawn but strong sunshine thereafter pushed the thermometer to 18.4C at 08.00, a very warm start to the day.
Variable cloud meant reduced strong sunshine yesterday (4.08 hours) but the thermometer did rise to a maximum of 23.3C, which is 1C above the mean. Late evening there was a very light shower amounting to 0.2C, the first rainfall after five dry days. The total rainfall for July is now only 10.6mm, which is 17% of the July mean. There followed another warm night with the minimum of 14.7C that is 3C above the mean.
After the extreme heat of tuesday, with a maximum of 31.9C, yesterday the thermometer peaked at 27.3C but began to fall during the late afternoon as the wind veered from the the southeast to the west. The past night was 8C cooler with a minimum of 12.5C, close to the meanfor July. The extreme heat and sunshine meant that the last two days has seen the equivalent of over 10mm of rainfall evaporate into the atmosphere. The total rainfall for July to date is 10.4mm when the mean is 61.0mm. The ground is still holding much of the heat as at 08.00 today the soil temperature at a depth of 5cm was 19.9C.
Yesterday was the hottest day this year in Marlborough when the thermometer soared to 31.9C just after 4.30pm. Last year the hottest July day occurred on the 1st with a maximum of 32.6C although the record was set on 19th July 2006 with a peak temperature of 35.1C.
Also memorable yesterday was the continuous strong (100watts/m2.) sunshine that totalled 15.79 hours. This is the highest number of hours recorded this year and beats the previous high set on 30th June last year.
Broken cloud moved across during the evening that reduced the radiation of the extreme heat from the ground into the atmosphere that produced a very warm night with a minimum of 20.4C. just after 5.30am. This is a record for my station that started operating in 1984, the previous high being set on 20th July 2006. By 8.00 am today the thermometer had risen a little to 21.2C.
Due to the minimal rainfall and higher temperatures over the last four days the soil temperature at a depth of 5cm rose to 23.1C at 8.00am
This month we have had very little precipitation; the total for the first 19 days is 10.4mm, which is a fraction of the mean for July of 61.0mm. Not surprisingly, the total for the equivalent rainfall lost through evaporation from plant life, water surfaces and the ground is 55mm giving a deficit so far this month of 45mm.
The thermometer soared yesterday as a result of the hot air from the continent reaching a peak of 28.8C, the hottest day since 1st July 2015. There was very little cooling breeze, a maximum gust of just 9mph and 9.55 hours of strong sunshine, the sunniest day since the end of May.
With a minimum overnight of 14.4C, the temperature had recovered to 20.4C at 08.00 and the soil temperature at a depth of 5cm now the highest this season at 21.1C.