Hawke’s Bay Weather Specific Information

Factors Specific to Tukituki Catchment Topography Lies to east of mtn ranges which rise to over 1800m. Sheltered from predom westerly winds. Result is sunny, less windy climate (than in West) with warm summers and mild winters Vulnerable to Easterlies that come about as result of a depression (low pressure) Leads to regions extreme rainfall variability

Position in relation to large-scale weather systems affecting NZ (See other notes) NZ is traversed at 6-7 day intervals by a series of eastward moving anticyclones (high pressure), to the north in Winter/Spring and to the south in Summer/autumn. Anticyclone=anticlockwise moving air Eastern side is northerly/easterly winds and Western is westerly/woutherly Differences in the temperatures/humidity creates cold front normally from NW to SE Results in period of rain followed by W/SW winds Rarely straightforward and is affected by Tasman Sea and surrounding depressions

Specific to HB Most Highs are to the north of NZ As a result we get more Westerlies Ruahine Mountains soak up moisture We get sunshine Changes during winter months as Highs move south and depressions start to dominate the weather patterns

Variability Westerlies have little variation due to sheltering of Ruahines Varries greatly with Easterlies Varriability 10-20% greater than rest of NZ

Frost Is very common but may vary widely over quite a small area. – Most likely in flat areas where air on clear nights cannot drain away and valleys into which cold air will drift from higher ground. Two types, ground frost measured 25mm from ground and screen frost measured 120cm from ground. Ground frosts not so much of a problem for plants. Average no of screen frosts is 50 inland. – EX. Havelock N is frost prone and has >100 per yr and may occur in any season. May have > 40 screen frosts /yr, mostly in winter. Hastings may have only up to 5 screen frosts in a spring but up to 15 have occurred in some years

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