Motorists travelling to and from the National Fieldays are being warned of significant delays as bad weather, fallen trees and slips add to the heavy traffic woes heading to Mystery Creek.

Roads leading to and from Hamilton from the south are currently blocked leaving the thousands of people heading to and from the agricultural event stuck in traffic.

An aerial view of the Fieldays.

Waikato district road policing manager Inspector Freda Grace says a tree fell across State Highway 3 by the intersection with Airport Road this morning, causing delays for northbound traffic.

She says police and ambulance staff also attended a crash this morning between a truck and a fire engine on Hamilton's southern edge on State Highway 1 just before Cherry Lane.

'The collision happened after the truck driver braked in trying to avoid a large slip with the fire engine following appearing to have collided with it.

"Traffic coming down from Auckland is merging with traffic coming into Hamilton and the Fieldays from the east causing significant delays at Matangi Village. Motorists are warned that it is unlikely they will be able to get to their destination any time soon."

After a dip of more than 5000 in opening day's numbers compared to 2013, Fieldays organisers are predicting the 46th edition of the annual agricultural showcase to pick up as the severe weather conditions appear to have blown through.

Yesterday 21,353 people braved the damp conditions, down on last year's 26,648, with many visitors put off by the weather to now make the trip to Mystery Creek.

Yesterday's opening ceremony got off with a bang as announcer and Waikato native Te Radar rolled in on the back of a ruggedly rural dirt bike.

He joked the event has been around for longer than he has yet it still creates a sense of 'childlike glee”.

Fieldays chief executive Jon Calder says some of the operations team were at Mystery Creek overnight on Tuesday 'literally battening down the hatches” before opening morning.

Despite the weather organisers opened the gates to clear skies and sunshine, says Jon.

'Thankfully there was no significant damage done overnight, although some smaller marquees received slight wind damage,” says Jon.

Prime Minister John Key officially opened Fieldays 2014, welcoming visitors and acknowledging international business visitors, including representatives from China and Argentina.

The Argentinian site was officially opened yesterday boasting the largest delegation group at the event, with more than 60 business and government visitors.

As always, the Fieldays Innovation Centre and the Fieldays Kiwi's Best Kitchen were extremely popular with today's agricultural enthusiasts.

Fieldays 2014 is on June 11-14.