"August sits betwixt summer and autumn - so be prepared for hot and cool, dry and wet, windy and calm" - Craftycabbage.com
"Show August some respect - the clue's in the name" - Craftycabbage.com
After last year's dry, hot & sunny August, this year's was back to normal. Sunshine levels were disappointing but at least it rained enough to reduce the amount of back-breaking hand-watering needed. A couple of photos of the back garden at the start and end of the month. The buddleia was in full bloom early on (Photo 1) while the second flush of roses featured towards the end (Photo 2).
While August was cool in these parts, it was the warmest August on record globally, comfortably beating the previous record holder (August 2016). As El Nino conditions continue to develop in the Pacific Ocean, the probability that 2023 will, globally, be the warmest year on record becomes ever more likely. The El Nino-Southern Oscillation (ENSO) has a negligible effect on the United Kingdom's weather - even so, 2023 will still be a warm year in the UK.
Photo 1: August 4th in the Back Garden
Photo 2: August 27th in the Back Garden
A time-lapse slideshow of August's daily photographs can be found in Video 1.
Video 1: Daily Garden Photos (August 2023)
Summary of Weather Parameters for July 2023
Cooling and Heating Degree Days have been added to the list. Sunshine hours are estimated from average daily solar radiation values measured by the Davis weather station. A list of average and total weather parameters is given in Table 1.
After sizzling June, July and August were on the cool side with plenty of cloud, regular rainfall and not enough sunshine.
Table 1: Average/Total Weather Statistics for August 2023
August 2023
Weather Parameter
Value
Dates
Average Monthly Temperature
17 oC
Maximum Monthly Temperature
28 oC
9th & 10th
Minimum Monthly Temperature
7 oC
30th
Number of Air Frost Days
0
Number of Hot Days (> 25 oC)
8
Monthly Precipitation
36.8 mm
Greatest 24 h Precipitation
7.4 mm
17th - 18th
Number of Dry Days
16
Monthly Sunshine Hours (estimated)
163
Average Wind Speed
3 km/h
Highest Wind Speed
34 km/h
14th & 19th
Maximum Barometric Pressure (Sea Level)
1022.3 hPa
21st
Minimum Barometric Pressure (Sea Level)
983.4 hPa
2nd
Average Barometric Pressure (Sea Level)
1012.2 hPa
Heating Degree Days
77.4
Cooling Degree Days
34.2
Figures 1 & 2 present the daily temperature, rainfall and sunshine hours for August 2023 [to enlarge, click once on the charts]. The first week was cool and the middle two weeks were average before things started to cool down again towards the end of the month. Cool overnight temperatures meant it took time for the days to warm up even when it was sunny. And there weren't many outright sunny days - less than a third, in fact (Figure 2). Rainfall was regular with only one significant dry period of 5 days.
In Figures 3 & 4, weather parameters for August over the last four years are compared. August 2022 was something of an outlier with regards to its maximum daily temperature. Figure 3 suggests August daytime maximum temperatures are on the rise in contrast to nighttime minimum temperatures which are decreasing. We just need another 30 years of data to see whether this trend continues before we can confirm such an effect. This paper uses a more extensive data set for England and Wales to show the maximum summer daily temperature is increasing at twice the rate of the average summer daily temperature. I'm not aware of any reason why nighttime temperatures should decrease in a warming world - hence, for the moment, I'm just putting this down to noisy data over too short a time period.
Figure 3: August Temperature Data for the Period 2020 - 2023
As a gardener, the downward trend in rainfall is worrying; as a PV electricity generator the increase in sunshine hours is welcome. I promise not to get too concerned or too excited until we have a longer time series.
Figure 4: Rainfall & Sunshine Data (August 2023)
The UK Met Office's August weather report can be found here. They summarised August as a 'rather mixed and unsettled month, similar to July, with average temperatures. Figures 5 - 7 show, respectively, average temperature anomalies, relative rainfall, and relative sunshine hours for the United Kingdom (courtesy of the UK Met Office). Herefordshire is highlighted in all three figures and confirms the average temperatures with low rainfall and sunshine for the month of August.
Figure 5: UK Mean Temperature Anomalies for August 2023 (Met Office)
Figure 6: Relative UK Rainfall, August 2023 (Met Office)
Figure 7: Relative Sunshine Hours, August 2023 (Met Office)
Our nearest Met Office weather station at Credenhill, about 4 miles away, reports the August mean (1991 - 2020 average) temperature to be 16.51 ℃ with a monthly rainfall of 58.42 mm. Referring to Table 1, this August was slightly warmer than normal (relative to the 1991-2020 mean) with just 63% of a typical August rainfall.
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