Tuesday, 1 June 2010 - Monthly Climate Summary for ACT Monthly Summary - Product code IDCKGC25R0

ACT Monthly Summary in May 2010
A wet end to Autumn

• Wettest May since 1995; 10th wettest on record
• Above average mean temperatures
• 15th warmest may on record for maximum temperatures

An archive of previous monthly summaries for ACT Monthly Summary is also available, as are summaries for other states and many other climate summaries and diagnostics.

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Rainfall

Returning to the wetter conditions experienced in February and March, Canberra recorded 79.4mm of rainfall in May 2010, almost twice the May average of 44.1mm. This is the wettest May recorded in Canberra since 1995 (137.4mm), and the 10th wettest May on record. Rainfall was highest at Mt Ginini, which recorded 99mm throughout the month.

The rain fell over 9 days, which is similar to the historical average of 8.3 days. However, four of these exceeded 10mm, well above the average of 1.4 heavy rain days, with a maximum fall of 20.8mm on the 30th, associated with an East Coast Low off the NSW coast between the 30th and 31st. Of the two remaining high-rain days, one was associated with the passage of a cold front on the 5th, which brought 19.6mm to Canberra Airport and 28.0mm to the Australian Botanical Gardens, the highest rainfall recorded anywhere in Canberra during the month. The final and smallest high rain day was 11.2mm on the 26th, associated with the passage of a low pressure system.

Temperature

The mean daily temperature in Canberra during May 2010 was 9.9°C, which was 0.5°C above the historical average for May. This was associated with well above average maximum temperatures, particularly during the first half of the month, but closer to average minimum temperatures.

Maximum temperatures at Canberra Airport were 16.6°C during the month, 1.1°C above the historical average of 15.5°C and the 15th warmest on record. These were due to prevailing high pressure systems and northerly winds during the first half of the month, with temperatures between the 1st and 16th averaging 17.9°C, significantly above average for May. Cool changes in the last two weeks of the month associated with rain-bearing systems decreased the average temperature; however, it remained well above average for May. The warmest daily maximum recorded anywhere in Canberra during the month was 22.5°C at Canberra Airport on the 4th.

In comparison, minimum temperatures averaged 3.1°C during May, only slightly below the historical average of 3.2°C. These were associated with very low overnight temperatures during the middle of the month, with five consecutive days below 0°C between the 12th and 16th, the coldest consecutive May period since 2004. Temperatures reached -3.7°C on the 13th, the lowest May air temperature at Canberra Airport since May 29 2006 (-3.9°C). Nights were slightly warmer at Tidbinbilla, averaging 3.6°C, with the lowest temperature recorded anywhere in Canberra -4.8°C at Mt Ginini AWS on the 12th.

Wind

Canberra was dominated by northerly to westerly winds during May, forming 71% of afternoon winds, compared to a historical frequency of 60% from these directions. The highest winds during the month were recorded on the 30th, associated with the passage of an East Coat Low, with maximum wind gusts up to 87 km/h at Mount Ginini AWS (elev 1760m) and 65km/h at Tuggeranong in the city.

Other phenomena

Canberra averaged 6.6 sunshine hours during May, slightly above the average of 6.0 hours. One thunderstorm was observed at Canberra Airport, equal to the historical average. Frost was observed on 3 days in the middle of the month, associated with very low minimum temperatures, with fog recorded on 6 days.

Extremes

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Summaries

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Notes