SINGAPORE - Passengers arriving at Changi Airport in December may have to wait longer for luggage to be unloaded from the planes.

This is due to the higher occurrence of thunderstorms during the monsoon season.

During rainy weather, ground handlers may temporarily stop retrieving baggage from the aircraft, because there is no shelter where they work and it is a lightning-risk area, said Changi Airport Group (CAG) on Monday (Dec 4).

CAG said that in November, there were 225 cases of baggage delays due to bad weather, almost triple the monthly average of 78 cases recorded between January and October.

This means that passengers took longer than 35 minutes to get their bags after the aircraft is parked. CAG said that under normal weather conditions, nine in 10 passengers get their bags within 35 minutes.

The 225 cases in November accounted for about 1.5 per cent of the 14,971 arrival flights that month.

Wet weather is set to continue in the first fortnight of December, said the Meteorological Service Singapore last week (Nov 30), with moderate to heavy thundery showers expected.

Singapore has one of the highest occurrences of lightning activity in the world. On average, the island experiences 168 thunderstorm days per year - days in which thunder is heard over the island, and gives an indication of lightning activity.

CAG said that even when there is no rain, there could be lightning alerts issued by the authorities, and baggage handlers have to temporarily stop work.

"When there is lightning activity, there is also the possibility of a 'side flash', where dangerous static electric discharge occurs even when the workers are standing close to the aircraft and not in contact with any object," CAG said.

Passengers will be alerted of any baggage delays through monitor displays and signs at the baggage claim belts, CAG said, adding that a 90-second animated video will also be played showing passengers what happens at airside when a lightning alert is issued.

Affected passengers will be given refreshments such as bottled water, canned coffee, packet Milo and biscuits while waiting.

CAG said it has also upgraded some areas in the baggage claim halls of Terminals 2 and 3 into arrival lounges for passengers to wait at.

To better protect staff, CAG said that it has enhanced lightning protection measures from 2015. These include getting ground handlers to use wireless headsets, which cuts off the physical connection between the workers and the aircraft, thus removing the possibility of lightning-induced static discharge through the headset.

A lightning mast is installed at every aircraft stand to reduce the chance of lightning striking the tailfin of the parked aircraft, said CAG.

Since August this year, CAG said it has made it compulsory for all planes to practise "three-point aircraft grounding", which helps to prevent the accumulation of electrical charge, by dissipating them to the ground safely.

"The safety of airport workers is paramount to CAG. We seek passengers' understanding that we will do our best to present their bags for collection as soon as it is safe to do so, be it rain or shine," CAG said in a statement.