Philip Duncan’s blog from the New Zealand Herald:

How the weather can affect an election:

It’s not something we perhaps think about for Election Day but the weather can actually help decide who will win an election.

If you want a right wing government to win the election then you should pray for rain. If you want a left wing government – pray for a sunny, warm, day. Americans have the red states (McCain/Republican/right wing) and the blue states (Obama/Democrat/left wing). Rain or sun could turn a blue state red and a red state blue. In NZ the colours may be the other way around but the same logic could apply.

Of course, for the weather to actually affect the outcome of an election, the election itself must be a tight race. While Labour and National appear in the polls to be a considerable distance apart, the fact that we have MMP means that really it’s much closer – and either party could govern after November 8.

The weather may only affect voting by a small percentage…but if we were to have a decent rain storm there could be a 10% swing – helping secure a National led government. So what is Saturday’s forecast? I’ll get to that shortly – but first, what does the research say on weather vs election results.

According to studies in the USA for every 25mm of rain above normal the Republican Party received an extra 2.5% of the vote. Now while we can’t draw exact parallels to New Zealand politics it does make for an interesting twist to this Saturday’s election.

If we were to take this study as scientific evidence you could argue that a rain storm dumping 100mm of rain over an electorate could see a 10% drop in votes to the left. But the chance of this happening is pretty low. For it to have a massive affect to our election we’d have to see a rain storm like we saw back in winter that flooded much of New Zealand. That would also isolate many rural areas that often vote right wing – so perhaps rather than favour a particular party it might just ‘generally’ lower voter turn out.

There are a few theories as to why bad weather helps the Republican Party in America – and potentially right wing parties in New Zealand. Firstly, according to the research, undecided voters tend to vote towards a left wing party. If the weather is terrible on election day it lowers voter turn out – and perhaps the undecided don’t have the passion to ‘venture out’ into it.

Secondly, poorer people tend to vote for left wing parties, and, while this is a generalisation, transportation will play a role in this area. For example if you have to catch a bus to get to your polling booth then a wet, windy, day might be better spent indoors and not braving the public transport system operating on a Saturday timetable.

So, what is the Weather Forecast for the New Zealand Election?

The weather forecast for Saturday is still a bit of a toss up – and if you go by the above research, the drier it is, the tighter the race will be. Our Saturday forecast shows a low in the Tasman Sea moving in – some models show showers on Saturday, others show that system not arriving until late Sunday or even Monday. The weather itself appears to be ‘undecided’!

Some of the battleground districts are:

– Epsom – 60% chance of showers.
– Papakura – 60% chance of showers.
– Tauranga – 40% chance of morning showers – then becoming sunny.
– Ikaroa Rawhiti, (a Maori seat covering most of the east coast of the North Island, including Hawkes Bay and Poverty Bay) – Becoming sunny, although there’s a 40% chance of showers – a forecast to watch.
– Taupo – Should be sunny.
– Rotorua – Sunny – risk of an early shower.
– Otaki – 30% chance of a shower but looking mostly sunny at this stage.

As you can see the confidence in these forecasts isn’t terribly high due to the fact that Saturday appears to be a “transition” day between fronts/systems. We’ll update this forecast again on Friday, but based on these predictions the weather probably won’t have a dramatic affect on any results.

Of course, this is all just a theory but it is based on American research that was sited as “the most exhaustive empirical test of the weather-turnout thesis to date”. Ain’t that a mouthful!

One can’t help but think the American election stands to affect New Zealanders more than our own election (it’s definitely more interesting!) but either way, Saturday is an important day for New Zealand – politically and meteorologically.

Sources: NZ Herald, Weather.com. Study: The Republicans Should Pray for Rain: Weather, Turnout, and Voting in U.S. Presidential Elections,” by Brad T. Gomez, University of Georgia, Thomas G. Hansford, University of California, Merced, and George A. Krause, University of Pittsburgh; 2005.