MET REPORT Temperature
Table 1: Blenheim Weather Data – October 2018 October October 201 October 2018 compared LTA to LTA GDD’s for month -Max/Min¹ 118.3 114% 103.& GDD’s for month – Mean² 118.4 106% 111.5 Growing Degree Days Total Jul – Oct 18 – Max/Min 205.8 109% 188.0 Jul - Oct 18 – Mean 252.5 105% 239.7 Mean Maximum (°C) 19.0 +0.7°C 18.3 Mean Minimum (°C) 8.4 +0.6°C 7.8 Mean Temp (°C) 13.7 +0.6°C 13.1 Grass Frosts (<= -1.0°C) 2 Equal 2.1 Air Frosts (0.0°C) 0 Equal 0.1 Sunshine hours 266.1 116% 229.0 Sunshine hours – lowest 140.7 Sunshine hours – highest 299.6 Sunshine hours total – 2018 2070.2 103% 2003.6 Rainfall (mm) 33.8 57% 59.5 Rainfall (mm) – lowest 2.3 Rainfall (mm) – highest 161.0 Rainfall total (mm) – 2018 693.4 128% 540.0 Evapotranspiration – mm 107.7 105% 102.1 Avg. Daily Windrun (km) 229.6 77% 296.3 Mean soil temp – 10cm 12.6 +0.6°C 12.0 Mean soil temp – 30cm 14.8 +1.2°C 13.6
Period of LTA
October 2017
(1996-2017) (1996-2017)
121.1 126.1
(1996-2017) 228.7 (1996-2017) 271.0 (1986-2017) 19.2 (1986-2017) 8.6 (1986-2017) 13.9 (1986-2017) Nil (1986-2017) Nil (1986-2017) 247.4 1983 1969 (1986-2017) 2038.9 (1986-2017) 32.4 1961 2001 (1986-2017) 553.4 (1996-2017) 109.7 (1996-2017) 241.4 (1986-2017) 13.7 (1986-2017) 14.8
¹GDD’s Max/Min are calculated from absolute daily maximum and minimum temperatures ²GDD’s Mean are calculated from average hourly temperatures
October’s mean temperature of 13.7°C was 0.6°C warmer than the longterm average (LTA). October probably didn’t feel like a warm month as there were a number of ups and down in weekly temperatures as indicated in Table 2. The seven day period from 12 to 18 October was cool, with a mean temperature of 11.4°C, 1.7°C below the October LTA mean. However, the next seven days from 19 to 25 October were very warm, with a mean temperature of 16.5°C, 3.4°C above the October LTA mean. The warmest maximum temperature of 25.9°C was recorded on 20 October 2018. The coolest minimum temperature of 1.2°C was recorded on 13 October 2018. In five of the six years 2013 to 2018, the October mean temperature has been well above average (2014 below average). However, in the 11 years 2002 to 2012, the mean October temperature was never above average. Frosts
October 2018 was warm, with well above average sunshine hours and well below average rainfall and wind-run.
Two ground frosts and no air frosts were recorded in October 2018. No ground or air frosts were recorded in October 2017, the only year from 1998 to 2018 not to record a ground frost in October.
Table 2: Weekly weather data during October 2018
Growing degree-days (GDD)
Mean Max Mean Min Mean Rainfall Sunshine (°C) (°C) (°C) Deviation (mm) (hours) 1st - 7th 18.4 10.1 14.3 (+1.2) 0.0 61.4 8th - 14th 17.3 6.7 12.0 (-1.1) 6.0 57.3 15th - 21st 20.5 8.1 14.3 (+1.2) 0.0 74.2 22nd - 28th 20.7 8.8 14.7 (+1.6) 22.4 60.6 29th – 31st (3 days) 16.8 8.6 12.7 (-0.4) 5.4 12.6 1st – 31st 19.0 8.4 13.7 (+0.6) 33.8 266.1 October 2018 (+0.7) (+0.6) (57%) (116%) October LTA (1986 – 2017) 18.3 7.8 13.1 59.5 229.0 LTA – Long Term Average
The GDD graph (Figure 1) has been restricted to the period September to December in order to highlight some of the differences between recent seasons during these four months. Once the latter four months of the season (January to April) are added on the Y axis scale needs to become larger and it gets difficult to see the differences between seasons for September and October. 2011/12 has been included as the most recent cool season. 2013/14 is
October 2018 weather
6 / Winepress November 2018
