May 2009 Print

My May

Temperature: With a mean temperature for the month of 7.5C, this May was the coldest since 2001 and below the average for the past 9 years of 9.1C. The warmest day was the 16th with 21.6C the only day to exceed 20C, May 2002 holds my record at 25.4C. Coldest temperature was -1.4C on the 4th. The coldest May temperature I've recorded is -6.2C on 31st May 2001. There were 5 days where the temperature was at or over 15C, my May average is 10. There was 1 day when the temperature was at or above 20C, my May average is 3. May 2003 and 2008 didn't have any days at or over 20C. There were 2 days where the minimum temperature was at or below 0, my average is 5. May 2001 holds my record for 12 days where the minimum temperature was at or below 0.

Wind: (Records from 2001) The monthly wind run of 5291km is 136% of my May average of 3866km and the windiest May I've recorded. The least windy was May 2003 with a wind run of 3185km. On the 23rd, I recorded a 427km wind run for the 24 hour period. This is the windiest day of 2009 to date and the windiest May day I've recorded. The 20, 22, 23 and 24 May qualify as the top 4 windiest May days I've recorded.

Rainfall: May had 192.8mm of rain over 16 days, 241% of the average of 80mm over 12 days and was he wettest May I've recorded. The driest was 2007 with 21.2mm over 3 days.

Barometer: (Records from 2006) The average pressure for the month was below the average of 1014.3 hPa with 1009.0 hPa. The lowest pressure was recorded on the 17th, 984.1 hPa. The lowest minimum pressure for May I've recorded. The highest pressure was 1032.6, the second highest for May.

May 2009 Summary
Temperature
Mean 7.5 C
Mean Maximum 11.6 C
Mean Minimum 3.7 C
Maximum High 21.6 C (16th)
Maximum Low 9.1 C (16th)
Minimum High 5.8 C (20th)
Minimum Low -1.4 C (4th)
Wind Speed and Direction
Maximum Gust 64 km/h (23rd)
Mean 7.4 km/h
Wind Run 5291 km
Max Daily Windrun 427 km (23rd)
Prevailing Direction West Sth West
Barometer
Maximum 1032.6 hPa (25th)
Minimum 984.1 hPa (17th)
Mean 1009.0 hPa
Max Daily Change +17.2 hPa (17th)
Rainfall
Days with Measured Rainfall (Greater than 0.2mm) 16
Max Daily Rainfall 29.2 mm (10th)
Monthly Rainfall 192.8 mm
Humidity
Maximum 93 % (7th and 29th)
Minimum 39 % (15 and 16th)

May Daily Observations
Temperature Wind Rainfall Barometer
Date Min Max Mean Mean
(Km/h)		 Gust
(Km/h)		 Run (km) Prevailing Dir 10 Minute Max (mm) Total (mm) Min (hPa) Max (hPa) Change (hPa)
1 4.0 12.3 7.3 1.3 16 29 South Sth West 0.2 0.8 1020.5 1025.8 +5.3
Broken cloud for most of the day with occasional showers. Light winds.
2 5.2 12.6 8.3 3.4 24 78 East Nth East 0.2 0.2 1020.3 1024.7 -4.4
Early light shower, variable cloud and a reasonable amount of sun, NE winds.
3 0.3 13.1 7.1 2.3 22 53 East Nth East 0 0 1019.6 1022.1 -2.5
Some morning cloud but a mostly sunny day with light NE winds.
4 -1.4 13.5 6.3 2.5 18 56 East Nth East 0 0 1011.4 1020.8 -9.4
First air frost of the year. Clear and sunny with light winds
5 7.0 14.6 10.5 6.2 33 144 East Nth East 1.2 9.2 998.7 1010.8 -12.1
Cloud breaking mid morning but returning in the afternoon. NE winds turn southerly in the evening with rain at night.
6 5.5 10.2 7.7 8.5 40 197 South Sth West 1.4 25.6 998.5 1008.6 +10.1
Morning rain easing to showers in the afternoon and cloud breaking in the evening. Cold southerly winds.
7 0 12.2 7.1 4.0 28 93 East Nth East 0 0 994.4 1007.7 -13.3
Morning frost. Clear and sunny with cool NE winds, some cloud from evening.
8 4.9 8.9 6.8 11.7 43 271 West Sth West 0.8 15.2 993.0 996.8 +3.8
Morning rain easing to showers in the afternoon, some with hail after dark. Cold sou'west winds.
9 1.7 10.1 6.2 5.0 34 116 West Sth West 0.8 7.8 984.8 996.9 -12.1
Showers morning and night, some sun in the morning but overcast from midday. Light and variable winds during the day tending NE in the afternoon.
10 3.6 5.8 4.4 7.5 35 173 West Sth West 1.2 29.2 987.2 998.9 +11.7
Cold southerly winds, showers, some with hail from afternoon. The second coldest May maximum temperature I've recorded, the coldest to date being 28th May 2001 with 3.6C
11 0.5 10.4 4.6 3.0 28 70 West Sth West 0.6 5.8 997.9 1000.2 -2.3
Morning cloud clearing to a sunny afternoon with cool southerly winds.
12 0.8 10.4 5.3 0.4 14 10 West Sth West 0 0 993.8 1000.3 -6.5
Overcast with high cloud with a few sunny intervals. Little wind.
13 1.0 14.9 7.5 0.7 12 17 East Nth East 0 0 993.6 996.2 -2.6
Some cloud early morning and later in the afternoon otherwise sunny with light breezes.
14 0.9 16.6 8.4 2.2 19 52 East Nth East 0 0 993.0 998.1 -5.1
Sunny but some high cloud from afternoon. Variable breezes tending NE.
15 6.3 16.3 11.3 7.2 37 167 North Nth East 1.2 3.8 987.1 998.5 +11.4
Early rain clearing by dawn then sunny with northerly winds.
16 9.1 21.6 15.7 8.8 46 203 East Nth East 0 0 988.2 998.0 -9.8
Some cloud but mostly sunny with NE winds turning nor'west at times in the afternoon.
17 6.8 17.1 13.3 9.4 38 216 North Nth West 0.2 0.2 984.1 1001.3 +17.2
Sunny with some cloud. Nor'west winds.
18 4.8 16.6 10.1 7.7 43 179 East Nth East 0 0 994.0 1002.9 +8.9
Morning cloud breaking. Fresh cool southerly change in the afternoon with a few spots of rain in the evening.
19 3.2 11.0 6.7 8.9 61 204 West Sth West 1.8 15.0 994.8 1006.3 +11.5
Southerly change mid morning with strong winds and rain for a short time. Sunny and cool for most of the afternoon with a late cold southerly change preceded by a thunder storm to the west and winds strengthening during the evening.
20 2.3 5.8 4.1 18.3 61 423 West Sth West 0.8 13.6 1006.6 1019.3 +12.7
Cold with showers, some with hail and sleet and a few snow flakes. Southerlies, strong at times.
21 1.8 8.3 3.8 8.4 34 195 West Sth West 1.0 10.4 1018.8 1022.0 -3.2
Showers with sleet and the odd flake of snow in the morning, snow on the Port Hills. Cloud breaking in the afternoon with some sunny intervals. Overcast in the evening with further showers.
22 4.1 8.1 6.5 18.1 59 419 West Sth West 0.8 14.0 1017.4 1027.0 +9.6
Overcast with showers, strong southerly winds for a time in the afternoon.
23 5.6 9.7 7.5 18.5 64 427 South Sth West 1.0 16.0 1021.0 1027.7 -6.7
Morning showers turning to rain with strong southerly winds for a time from late morning. Rain easing in the afternoon along with the winds. Rainfall total for the month now makes this May the wettest I've recorded in 10 years of records.
24 7.4 9.0 8.1 17.6 44 407 South Sth West 0.4 16.2 1025.1 1031.5 +6.4
Showers and drizzle for most of the day with southerly winds.
25 6.3 9.6 7.3 6.7 27 154 West Sth West 0.2 1.0 1030.2 1032.6 -2.4
Overcast with some drizzle at times, southerly winds.
26 5.8 8.2 6.7 3.4 23 78 East Nth East 0 0 1023.5 1030.8 -7.3
Overcast with low cloud. Light NE winds.
27 5.7 8.4 7.3 7.5 29 175 East Nth East 0 0 1018.1 1023.5 -5.4
Overcast and cool with low cloud, NE winds.
28 5.6 12.9 8.4 9.8 38 227 East Nth East 0 0 1011.9 1018.0 -6.1
Some high cloud but mostly sunny for much of the day with NE winds. A colder southerly change mid afternoon bringing low cloud and fog.
29 1.4 11.6 6.3 2.2 21 51 West Sth West 0 0 1012.7 1016.2 +3.5
Morning fog clearing quickly, high cloud breaking about midday but returning a couple of hours later. Light NE winds turning light southerly from late afternoon.
30 2.3 12.0 6.5 1.1 17 25 West Sth West 0 0 1006.8 1016.1 -9.3
Morning cloud breaking then sunny with light southerly breezes.
31 3.0 7.0 4.7 15.9 58 368 South Sth West 1.2 7.4 1007.0 1023.7 +16.7
Cold southerly wind, showers, some with snow pellets and the occasional snow flake. Cloud breaking at times with sunny intervals.
May 2009 Temperature Graph May 2009 Wind Dir Graph May 2009 Wind Dir % Graph May 2009 Wind Speed Graph May 2009 Rainfall Graph May 2009 Barograph May 2009 Humidity Graph
 

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