January 2005 cooler, calmer than 2004

With the proliferation of automatic weather stations, manual weather recordings for Tawa will cease at year’s end. Summaries of the readings taken over the 3 years to 2005 will be progressively published to provide background data for the recently installed automatic weather station.

These manual readings are obviously subjective, and represent the microclimate where the observations were made. However, gardeners might find the data of use in understanding germination, flowering and other crop problems.

Tawa’s climate during January 2005 was slightly cooler and calmer than the same month in 2004. Weather data for January 2003 is incomplete.

Readings taken at Tawa:
The lowest January temperatures were 7 (2003), 10 (2004) and 8 (2005).
The average daily low temperatures were 13 (2003), 12 (2004) and 11 (2005).
The highest January temperatures were 29 (2003), 28 (2004) and 28 (2005).
The average daily high temperatures were 23 (2003), 19 (2004) and 18 (2005).

Days with frost: no data (2003), none (2004), none (2005).
Days with rain: no data (2003), 11 (2004), 10 (2005).
Days with thunderstorms: no data (2003), none (2004), 1 (2005).
Days with hail: no data (2003), none (2004), none (2005).
Days with strong winds: no data (2003), 7 (2004), 5 (2005).

January 2004, despite the odd bright day, is memorable for a windy and cloudy period that became known as Wellington’s “year without a summer”. It wouldn’t be until February that Wellingtonians knew how apt this label was to be.

January 2005 will be remembered for yet another region-wide flood event. At Tawa, the rain commenced as drizzle on the afternoon of Wednesday the 5th and steadily grew heavier, reaching a rain rate of 32 mm/hour at 8:55 p.m. By 11 a.m. on the 6th, 49mm of rain had fallen since commencement of the rain event. Further afield, there was flooding at Otaihanga on the Kapiti Coast and in the Hutt Valley, with houses being evacuated. State Highway 1 had been washed out at McKays Crossing, as had the North Island Main Trunk Railway line. The rain eased during the afternoon, and the weather at Tawa became partly cloudy and humid.

Rain began falling again on the morning of Saturday the 8th with 31mm of rain falling in the three hours to 10:30 a.m. at which point a maximum rain rate of 86 mm/hour was reached, causing gutters to overflow and abrupt surface flooding on soils already saturated from the event two days earlier. Most of that morning thunderstorms passed overhead, causing crockery to rattle in the cupboards with resounding thunderclaps.

The rain eased to showers by 1 p.m. bringing the rainfall total to 39mm but thunderstorms continued to pass overhead until mid-afternoon. By this time the Wellington region was yet again isolated from the rest of the North island with both roads north closed and surface flooding was reported at Paekakariki and in the Hutt Valley.

The rain eased to drizzle and stopped early on the morning of the 9th, allowing road and clean-up crews to begin their work in earnest.

Fortunately for residents, the soft clay soils had started to dry out by the time two swarms of earthquakes struck the region later in the month. The first commenced near Martinborough on the 18th January 2005, with the seven events getting progressively larger until the magnitude 5.4 quake of February 1st. The second swarm of 5 earthquakes commenced near Upper Hutt on January 21st. The largest member of this swarm which ended on the 23rd was magnitude 5.5

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