Service director Arona Ngari says although it could be expected to be cooler at this time of the year in the tropics, temperatures had been running at about 2°C lower than average in July and August.
He says cloudier days are expected over the next few weeks that will bring some eagerly-awaited warmer days for Rarotonga residents and visitors.
“We do, however, have to keep an eye on those high pressure systems (anti-cyclones) that come from New Zealand as they tend to blow those icy winds from the deep south towards the Cook Islands,” Ngari says.
“So whenever you see an anti-cyclone mentioned in the weather forecast, take a cardigan or pullover with you in the evenings when you are going to be outdoors.”
The cooler weather conditions are due to the onset of the El Nino earlier in the year. This has strengthened in recent months extending cooler than normal weather across islands east of the dateline.
Ngari, who was in Nuku’alofa last month for a regional weather conference, says Tonga has been experiencing similar weather to the Cook Islands lately.
The lowest temperature recorded so far this year was 14°C on July 29 at 6am. The lowest temperature ever recorded in the Cook Islands is a chilly 9.8°C, and it happened back in 1965.
Low rainfall has been also recorded so far this month with the highest a mere 4.8 millimeters on August 12.
“Due to the high pressure systems that dominate the mid-latitudes during these months, there is the tendency to have less than normal cloud cover. The result is that radiation received during the day is not kept on land at night due to heat being released back into the atmosphere,” Ngari says.
“As no cloud is present, the heat is lost back into space. Clouds act like a blanket at night that keep the heat within the space of the clouds and land.
“When clouds are missing, the land is then stricken with cold air.”