In order to be pretty safe from bad weather it was necessary to choose a high pressure condition. Further, the high pressure would have to lie north of Spitzbergen so that the aeroplanes should not fly out of good weather directly into bad on the way north. A high pressure condition over the Pole would necessarily bring with it northeasterly winds and cold weather in Spitzbergen. This northeasterly wind would (at West Spitzbergen) be an off-shore wind and therefore would signify clear weather. Along the north coast of Spitzbergen the weather would be more doubtful, with a northeast wind which would cause the air to rise up against the hills and form clouds. But these cloud-masses on the north coast would very often only stretch out over a limited area which the flyers could pass in a short time, preferably by flying over the clouds. One has the best guarantee for stable weather conditions when the pilot balloons show that northeast winds are not only to be found on the ground but also higher up. One knows then that the high pressure condition around the Pole will reach high up in the atmosphere and is not just a low formation which could be swept away by the first attack of a storm center from elsewhere. The first high pressure condition in May occurred on the 4th, just when the aeroplanes were finished mounting. This favorable condition did not last long. The low pressure over North Norway increased and passed northeast (along the dotted line on the chart) by pushing the polar high pressure aside towards Greenland. Before the final preparations were finished on the 8th of May the low pressure had got so near the Pole that it was not advisable to start. A period of drizzly weather followed now when it was impossible to do anything else but wait. The wind was mostly between west and south, and the sky was overcast and we often had snow showers. Only now and again it cleared for half a day, but never long enough that there could be a question of starting. This state of affairs lasted until the 18th of May, when a change took place. A heavy storm center, which passed Björnöya, turned the wind easterly at Spitzbergen, and behind the bad weather a high pressure region appeared which moved from Labrador via Greenland towards the Pole. The wind was still too strong, and it was not quite clear at Spitzbergen, but there were good prospects that the next few days would bring good weather conditions for the flight. The planes were therefore made ready to start at short notice.