Most of Europe has been hit by freezing weather from the north east this week, resulting in snow as far south as northern Spain where this week's test is taking place.

Limited visibility and a thin blanket of slushy snow over the Circuit de Catalunya on Wednesday morning meant the medical helicopter was unable to operate and the start of the session was postponed until midday.

But with the air temperature only just above zero and track temperatures just a couple of degrees warmer when the track opened, there was no action for the first hour and ten minutes of the session.

Fernando Alonso's bright orange McLaren finally broke the silence at 13:10 when he went for a single exploratory lap on full-wet tyres. Although no performance data could be gathered from the run, it was the first time the McLaren had left the pits since an exhaust issue melted the car's wiring loom on Tuesday afternoon. By the end of the day Alonso had completed a further nine laps, including two complete laps and a best lap time of 2:18.545.

Daniel Ricciardo was the next driver to hit the track in the Red Bull and completed two laps in total. On his second lap he ran wide into the gravel and after returning to the pits with debris in his sidepods, the team decided to call it a day.

Red Bull's Daniel Ricciardo was caught out by the tricky conditions and went through the gravel trap on day three of pre-season testing in Barcelona. Patrik Lundin/Getty Images

Brendon Hartley in the Toro Rosso completed two laps while Marcus Ericsson in the Sauber and Robert Kubica in the Williams finished the day with one lap each. The rest of the drivers opted against running at all.

The teams also saw their plans curtailed on the opening two days of this week's test due to difficulties getting Pirelli's slick tyres up to temperature in cold but dry conditions. As a result, the workload for all teams will be piling up with just five test days remaining before the first race in Australia next month.

Dry but overcast weather is expected for Thursday before the sun is forecast to return for all four days of next week's test.