Column written by Philip Duncan for the Herald on Sunday. Philip is an independent voter and the story is based on a scientific study out of the US.

The type of weather we have on Election Day can help shape the results, according to studies out of the United States.

In a nutshell, rainy weather helps boost the success of a right-wing party while warm, sunny weather will improve the chances of a left-wing party.

Of course, for the weather to actually affect the outcome of an election, the election must be a tight race.

While National and Labour appear in the polls to be a considerable distance apart, the fact we have MMP means it’s always a much closer race – especially with the ongoing political dramas this election season.

The weather may only affect voting by a small percentage … but with a decent rainstorm there could be a 10 per cent swing – helping secure a National-led government.

So what does the research say on weather vs election results?

According to studies in the US, for every 25mm of rain above normal, the Republican Party (right wing like National) received an extra 2.5 per cent of the vote.

If we were to take this study as scientific evidence you could argue a rainstorm dumping 100mm of rain over an electorate could see a 10 per cent drop in votes to the left.

There are a few theories as to why bad weather helps the right in America – and potentially right-wing parties here 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 turnout – and perhaps the undecided don’t have the same passion as loyal party voters to venture out into it.

Secondly, poorer people tend to vote for left-wing parties and transportation plays a role. If you catch a bus to your polling booth, a wet, windy day may be better spent indoors and not braving the public transport system on a Saturday timetable.

So, what is the weather forecast for the New Zealand election?

Early indications show south-west winds brisk to blustery in many places but mostly dry weather over. That should lift the voter turnout and will give hope to Labour and left wing parties.

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