If the weather today is as bad as the forecast suggests, it could reduce voter turnout - and that could have an impact on the result.
"Traditionally, lower turnout favours the Tories," says ITV News. But if turnout is reduced specifically due to poor weather, it's less clear who it will favour.
"If the old stay at home, that's bad news for the Tories; if the young, that's bad news for Labour."
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What's is the forecast?
"Bands of rain or showers affecting the UK, with the risk of hail and thunder on Thursday," said the Met Office.
Channel 4 weatherman Liam Dutton said polling day "will see heavy rain and a brisk breeze sweep northwards across the UK".
But he added: "Despite being an unseasonably unsettled day for June, very few places will see an inch of rain – probably only the hills of Wales, north west England and south-west Scotland. Everywhere else is likely to have half an inch of rain or less, with some eastern parts of England seeing nothing at all.
"Even if weather conditions do affect UK voters, the rain we're due on Thursday is unlikely to be enough to make a big splash."
Does bad weather affect turnout?
Researchers in the US concluded turnout falls by about one per cent that each inch of rain that falls. Studies in Spain and the Netherlands found a similar negative relationship between rain and turnout.
In Sweden, however, no statistically significant relationship has been found - and there are "many reasons why the experience in the US would not be replicated in Britain", says Channel 4.
"There's no strong data either way in the UK and there won't even be that much rain on election day this year."
So will it affect the result?
Shami Chakrabarti, a member of Jeremy Corbyn's shadow cabinet, blamed the rain in Copeland for Labour's by-election defeat in February, saying the party's voters were less likely to have cars.
However, experts say there is no evidence from the UK to suggest bad weather stops people from voting.
"There's basically no correlation between the weather and turnout," Stephen Fisher an associate professor of political sociology at Oxford University told the BBC.
John Curtice, professor of politics at Strathclyde University, agrees. "We've had one or two general elections when it's been raining in some parts of the country and not in another and there has been no significant variation in turnout," he says.
