When we jump

Skydiving is an air sport, and the weather sets the calendar rather than the other way round. That is worth knowing before you buy a voucher with a particular date in mind: a voucher buys a jump, not a day.

Season and jumping days

We jump from April to October, at weekends and on selected weekdays.

Spring, summer and autumn

The season falls into three quite different parts, and each has its own reasons to jump and its own reasons to wait. What follows describes the weather, not a promise: on any given day the conditions at the dropzone decide.

Spring

In spring the air aloft is still cold. Temperature falls by about 6.5 degrees for every kilometre, so with ten degrees on the airfield it is around minus fifteen at 4,000 metres. The weather changes fast: behind a cold front comes very clear air, often with passing showers and gusty wind, and in the Polish climate early spring is windier than summer.

Cool, dense air has one advantage the tandem equipment manufacturer points out: the canopy performs better in it and flares more strongly for landing. While the water is still cold, fog can also settle over the bay itself, as described further down.

Summer

In summer the days are longest: in June the sun rises over Gdańsk before 4:30 and sets after 21:00. Warmth has its own rhythm, though. Mornings are often calm; through the day cumulus builds, thermals and gusts appear, and in the afternoon passing thunderstorms. In the heat the air is also thinner, so according to the equipment manufacturer landings can be noticeably faster and harder, and in a stagnant high haze collects and takes away the distant view.

Autumn

In autumn the air cools again, and behind the fronts it can be very clear. September is one of the calmer months, since the Polish climate is least windy in summer and early autumn. The days shorten quickly: at the end of October, after the clocks go back, the sun sets before 16:30 and rises later, so an autumn day is shorter at both ends. Long, clear, still nights encourage morning fog, which only lifts once the sun has warmed it.

Daylight only

A tandem is a daytime jump. The manual for the UPT Sigma 2 system we jump rules out tandem jumps before official sunrise and after official sunset. In Gdańsk that means more than 17 hours in June and fewer than 10 at the end of October, and the difference is simply a difference in the hours in which the aircraft can take jumpers up.

What stops jumping

Wind, cloud, visibility and rain all have to agree at once. Any one of them can close the day on its own, even when the others are fine.

Wind

Strength, gusts and direction all count, on the ground and at altitude. On the ground the wind decides the landing: a tandem canopy has its own airspeed, and strong wind and gusts, which turn into turbulence behind trees and buildings, make an approach that an instructor will not fly with a passenger. At altitude the wind moves the exit point: the harder it blows, the further from the landing area you leave the aircraft, and the wind at 4,000 metres can be quite different from what you feel on your face.

There is no single number that applies everywhere. The US Parachute Association (USPA) sets a ground-wind limit only for solo students, 14 miles per hour or about 6 m/s, and none for tandems. The manufacturer of the system we jump gives no number either: its manual tells the instructor to keep assessing the wind and to judge it conservatively. So the limit is set by the equipment, the instructor and the particular day.

No wind at all can be a problem too. The same manual advises against taking heavier passengers, and anyone who cannot run or support their own weight on their legs, on windless days, because the landing is harder.

Cloud

Nobody jumps through cloud. The equipment manufacturer's manual requires the instructor to check before every exit that visibility and distance from cloud are within the rules, and from above you have to see the ground to leave the aircraft over the right spot. A solid layer below 4,000 metres therefore closes jumping from that height, even with sunshine above it. Scattered clouds usually just hold a flight until they pass.

Visibility, rain and storms

Fog, low cloud and thick haze end things faster than wind does. Rain usually does too: it comes with a low cloud base and poor visibility, and at freefall speed raindrops hurt. A thunderstorm nearby shuts jumping down before it starts to rain, because the wind ahead of a storm cloud can change direction and strength within minutes. A front crossing the dropzone does much the same even without rain.

Cold

Cold on its own does not stop jumping, but it changes what you wear. In April and October it can be around minus fifteen at exit altitude, so layers matter, and if conditions call for it you will be given a jumpsuit to wear over your clothes at the dropzone. Freefall lasts about a minute, too short to get cold; several minutes under the canopy in cold air you will feel more.

What waiting at the dropzone looks like

The decision is not made once, in the morning, for the whole day. Polish parachuting regulations require the organiser of the jumps to analyse the weather, and it is assessed throughout the day. A day with a pause in jumping therefore looks ordinary: people wait on the ground, the instructors watch the sky and the forecasts, the aircraft stays put, and then a window opens or it does not.

1. 01If it is already clear in the morning that the day has no chance, we get in touch before you set off.
2. 02If conditions are marginal, you wait at the dropzone. A window can open for an hour, and then everything moves quickly, so stay close and keep your phone on you.
3. 03While you wait, do not drink, not even one beer to pass the time. Anyone under the influence does not jump that day, even if the weather improves.
4. 04If no window opens, we ring or write and arrange a new date, at no extra cost.

The season and your voucher

A voucher is valid for 12 months from purchase, and the season comes back in the same months every year, so any 12 months of validity cover it in full: sometimes in one piece, sometimes in two. Bought in winter, a voucher waits for the whole of the next season. Bought in summer, it has the rest of this season ahead of it and the start of the next, but not its end, which is worth knowing before you put the jump off until next autumn.

Planning so that it works

• Do not leave the jump for the last weeks of the voucher's validity. Leave room for at least one reschedule.
• Do not plan it for the day before a wedding, a flight or anything else that cannot move.
• Book out the day rather than the hour. The order of jumps follows the weather and how busy it is.
• If you are coming as a group, say so when arranging the date, because it is then easier to fit you into one window.
• Check the forecast, but do not cancel on your own. The decision is made at the dropzone on the day.
• If the weather takes several dates from you in a row, write to us before the voucher expires.

When the air over the bay is clear

A cloudless sky and clear air are two different things over the Baltic. Haze begins once visibility drops below ten kilometres and sits in a shallow layer just above the ground, so a day can be sunny while the far horizon is still blurred. Very clear air usually comes in behind a cold front and after rain: cold, well mixed and low in dust. That is when the bay and the line of the shore look sharpest.

So a hot afternoon can show less water than a cool, clear morning: in a stagnant high the air collects dust, and the day's warmth mixes the layer near the ground and builds cumulus. The coast also does the reverse: a clear sky over the land while the bay lies under a white lid of fog, which slides in when warm air moves over cold water. At 4,000 metres the haze is below you, so the ground stays sharp while the far shore softens. None of this decides whether jumping goes ahead, only how far the view reaches; the guide to what you can see from 4,000 metres goes into it.

Time of day

Mornings tend to be calmer: wind usually builds through the day, and in summer the afternoons add cumulus and gusts. In autumn it can be the other way round, with morning fog sometimes hanging on until late morning. Late afternoon has lower, warmer light, which matters if you have chosen a filmed variant. If you have a preference, mention it when you arrange the date.

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