September 2017 was the second wettest ever recorded here with rain being recorded on 23 days. Temperatures were below normal and winds were slightly below average.
The maximum temperature in the month was 21.2°C recorded at 18:11 on the 4th, 2.6°C below the average monthly maximum. The minimum temperature was 4.8°C recorded at 08:04 on the 19th, 0.5°C below the average minimum for September. This was the lowest temperature since 4.1°C was recorded on May 11th 2017. The average temperature in the month was 12.7°C, 0.7°C below the September mean. The average daily maximum was 16.9°C, 0.8°C below the mean, with the average daily minimum being 9.0°C, 0.7°C below the mean. The warmest day was the 4th with an average temperature of 16.2°C. The coldest day was the 15th with an average temperature of 10.1°C.
The highest dew point was 18.5°C recorded at 16:55 on the 4th, 0.7°C above the average. The lowest dew point was 3.9°C recorded at 08:04 on the 19th, 0.1°C above average. The average dew point for the month was 10.5°C, 0.2°C below the September mean. The high wind chill was 21.2°C at 18:11 on the 4th, with the low wind chill being 4.8°C at 08:04 on the 19th. The average wind chill in the month was 12.5°C. There were 110.83 hours of sunshine, with the sunniest day being the 19th when 7.76 hours was recorded.
September 2017 was the wettest month since December 2015 with 63.8 millimetres of precipitation being recorded on 23 days. This was the second wettest September recorded here, beaten only by the 70.6 millimetres recorded in September 2010. The wettest day was the 25th when 9.8 millimetres was recorded. A further 7.4 millimetres was recorded on the 5th. The highest rain rate was 45.6 millimetres per hour at 18:26 on the 9th. There has now been 357.6 millimetres of rain so far in 2017, 89% of the average for the end of September.
The highest barometric pressure was 1023.0 millibars at 10:29 on the 26th. The lowest barometric pressure was 983.4 millibars at 06:45 on the 11th. The average pressure in the month was 1011.0 millibars. The highest humidity was 100% and the month average humidity was 87%, a record for September. The lowest humidity was 54% at 15:36 on the 1st.
The highest wind gust in the month was recorded at 04:07, making it the highest September wind gust since 39.1 mph was recorded on September 12th 2011. The average gust speed in the month was 4.6 mph, mean 5.5 mph. The average wind speed was 2.7 mph, mean 3.4 mph. The maximum wind speed was 19 mph at 05:36 on the 13th. 1.4 mph below the mean. The total wind run was 1958.4 miles, with the predominate direction being 186°.
The maximum high solar radiation recorded at 13:35 on the 13th was 974 w/m². The average solar radiation for the month was 105 w/m². The highest U.V. Index was 4.6 set at 13:52 on the 4th.