Teams are concerned about a forecast of bad weather for the final week of pre-season testing, according to the German language Speed Week.
Last week, the ’middle’ Spanish test ended with cold and wet conditions at the Circuit de Catalunya.
"I can’t remember having a full test day this cold," said Australian Mark Webber.
More of the same is en route again to northeastern Spain.
The last four days of testing before the season opener in Australia begins in Barcelona on Thursday, and on the morning of the opening day "it will start raining", predicted correspondent Mathias Brunner.
The cold weather and rain is forecast to continue on Friday and possibly into early Saturday, with only the last day of running on Sunday so far looking sunny.
As well as scanning the radar images, eyes this week will also be straining to catch a glimpse of rival teams’ final Melbourne-spec technical packages.
Germany’s Auto Motor und Sport has already spied conspicuous and mysterious ’holes’ on the Sauber, Ferrari and Red Bull cars.
Sauber began the trend for nose inlets last year, and now the new Ferrari has a hole that resembles a shark’s mouth in the area beneath the nose of the car.
"And if you look closely," said correspondent Tobias Gruner, "you can also recognise an intake on the Red Bull."