The number of refugees and migrants arriving on the Greece islands dropped drastically for one day over the weekend from an average, officials said Tuesday.

The International Organization for Migration said this "drastic decrease" saw just 155 people land on the islands Sunday. This was in stark contrast to the rest of November, in which an estimated 100,000 people landed in Greece, an average of almost 4,500 per day.

On the Greek mainland there were fewer than 500 arrivals in Athens and the northern seaport of Kavala on Sunday compared with nearly 8,000 the previous day, the IOM added in a statement.

Migrants and refugees arrive on Tuesday on the Greek island of Lesbos after crossing the Aegean Sea from Turkey. BULENT KILIC / AFP - Getty Images file

Alexandra Flessa, a staffer at the IOM office in Greece, said that one explanation for the temporary drop could be due to training exercises which were being held by the Turkish coast guard on Sunday and Monday.

"We do not know if the Turkish coast guard was stopping the migrant boats, or whether the people-smugglers were informed they were there and didn't even try to launch vessels," Flessa told NBC News. "There were also high winds, so it could have been a combination of these factors."

In addition, the IOM said 14 of the 23 days in November so far had seen no deaths in Greek waters — making November the safest month since August.

PHOTOS: Europe Clamps Down on Borders, Leaving Migrants Stranded

However, Sunday's lull appeared to be temporary. An estimated 3,000 refugees and migrants landing on the Greek island of Lesbos alone on Tuesday, Flessa said.

Peter Bouckaert, emergency director at Human Rights Watch, said on Twitter that 34 migrant boats had arrived on the island by 1 p.m. local time (6 a.m. ET).

34 boats so far arrived on Lesbos today after lull over the weekend, no end in sight 2 crisis. pic.twitter.com/DvbUICBvXA — Peter Bouckaert (@bouckap) November 24, 2015

Migrant and refugee numbers have dropped in Italy across a wider period, with 1,708 arrivals in the first three months of November compared with 5,342 in the same period in October, the IOM said.

However IOM Italy spokesperson Flavio Di Giacomo said in a statement that "this is a decrease that does not surprise us, as it is normal to register a drop of arrivals in November."

Related: Refugee Versus Migrant: What's the Difference?

While sea routes appeared to quieten, temporarily at least, days long-protests continued among the 1,000 refugees and migrants stranded at a border crossing between Greece's and Macedonia. The bottleneck flared following the decision by the Macedonian government to allow only Syrians, Afghans and Iraqis to enter.

More than 850,000 refugees and migrants have arrived in Europe by sea this year and around 3,500 people have died at sea, according to the IOM's figures.