Monthly weather forecast and climate
Northern Mariana Islands, USA

Flag of Northern Mariana Islands, USA
Flag of Northern Mariana Islands, USA

The climate of Northern Mariana Islands

The Northern Mariana Islands experience a tropical rainforest type of climate (Köppen climate classification Af) with abundant rainfall. The climate is equable throughout the year, with little seasonal variation in temperatures. The Northern Mariana Islands constitute a United States territory that lies in Micronesia in the northwestern Pacific Ocean. The vast ocean, tropical latitudes, and trade winds dominate the climate of the islands. Typhoons present a significant threat year-round but frequently occur during the rainy season.

Northern Mariana Islands lie 15°to the north of the equator in the Mariana archipelago and experience sunny days throughout the year. Fourteen islands constitute the commonwealth, out of which Saipan, Tinian, and Rota are the largest. The islands lie in a general north-south direction, with Farallon de Pajaros at the extreme north and Rota in the extreme south. The northern islands are of volcanic origin, while the southern consists of limestone and coral reefs. Agrihan, Pagan, Anatahan, and other northern islands have active volcanoes. Mount Agrihan has the highest point on the islands, with an elevation of 965 meters.

The Northern Mariana Islands have pleasant weather for the majority of the year. Out of the two main seasons, the dry one lasts from December to June, while the wet season is from July to November. June temperatures are the highest during the year, while February is the coldest. Temperatures are rarely extreme and mostly average between 70°F (21.1°C) to 90°F (32.2°C). The temperatures rarely vary by more than 10°F (-12.2°C) between day and night, and there is little seasonal variation. The coldest temperatures average between 72°F (22.2°C) to 75°F (23.9°C) from December to February, while the hottest temperatures average between 83°F (28.3°C) to 85°F (29.4°C) from
June to November.

Two-thirds of the year is wet, and even the dry season experiences significant rainfall with one-third of the annual rainfall. July to October is the rainiest period in the Northern Mariana Islands, which contributes to over fifty% of the yearly precipitation. The southernmost three islands in the chain are wetter than the rest, which see more rain on the slopes of the interior mountains. The annual sunshine lasts for 2200 hours, and the humidity is tenable even though the location is in the low latitudes. Days and nights are of roughly equal duration, and the rainfall is typical of the tropical islands of the Pacific Ocean. Northeasterly trade winds drive away the clouds during the dry season. Wind speeds mostly remain below an average speed of 20mph (32.2km/h).

The highest temperature on record for the Northern Mariana Islands is 90°F (32.2°C), while the record lowest temperature is 63°F (17.2°C).

The best time to visit Northern Mariana Islands

The best time to visit the Northern Mariana Islands is during the dry season from December to February when the precipitation is moderate. The coldest period of the year has pleasant temperatures that average between 73°F (22.8°C) to 81°F (27.2°C). March, in the second half of the dry season, is suitable for budget travelers than the first half. The sea temperatures are mild, and the conditions are calm. The relative humidity is less, which makes outdoor excursions enjoyable on the islands. Avoid Japanese national holidays during April and May as the visitor numbers peak during these months.

The worst time to visit Northern Mariana Islands

The worst time to visit the Northern Mariana Islands is between August to November when the typhoon season is at its peak. Hurricanes and tropical storms bring the destructive force of nature and often see winds above 100mph (160.9km/h) and huge tidal waves. The rainfall is intense, occurs almost every day, but rarely last for extended periods. The cloud cover sees an increase, as does the humidity and the heat index. August is the worst offender with the highest rainfall, humidity, and incidences of storms.

Weather hazards

The Northern Mariana Islands are prone to thunderstorms, tropical cyclones, earthquakes, and volcanic eruptions. The Anatahan volcano is in an active state since May 2003, with an ejection of more than 50 million cubic feet of ash and rock. Volcanic smog, black clouds drift over to the southern islands of Saipan and Tinian many a time. The typhoon season lasts from August to January, with peak incidences from August to November. Thunderstorms are frequent, along with lightning and rain. Tropical storms bring heavy rains in the Northern Mariana Islands. The islands are prone to seismic activity and record moderate intensity earthquakes.

Weather in January

January is pleasant in the Northern Mariana Islands with blue skies welcoming the New Year. The daylight lasts for at least 11 hours, even during the relatively cold season. Turquoise blue waters await the tourists with miles of white, soft, sandy beaches that soothe the soul. The average temperatures in the modest range of 73°F (22.8°C) to 82°F (27.8°C) keep the atmosphere bright as the typhoon season ends. Weather in January »

Weather in February

February is the coldest month of the year in the Northern Mariana Islands, with the average temperatures remain in the 73°F (22.8°C) to 80°F (26.7°C) range. Clear, blue skies are the general theme except for short periods of rain, typical of the tropics. Weather in February »

Weather in March

March is as dry as it can get ever become in the year in the Northern Mariana Islands with only 2.4" (61mm) of rainfall. However, one out of every two days receives at least light showers. The directly overhead sun casts bright light that lasts for 7 hours within the 12-hour days. Weather in March »

Weather in April

April is slightly wet in the dry season in the Northern Mariana Islands with an average of 5" (127mm) of rainfall. The average temperatures are in the 74°F (23.3°C) to 83°F (28.3°C) with 7 hours of bright sunshine and relative humidity less than 75%. Weather in April »

Weather in May

May is hot in the Northern Mariana Islands with the average temperatures in the 76°F (24.4°C) to 84°F (28.9°C) range. The sunlight is intense, and sunscreen becomes mandatory as the ultraviolet rays reach dangerous proportions. The light precipitation lasts for short durations during the day and gives plenty of time to explore the islands on foot, bikes, or boats. Weather in May »

Weather in June

June is the driest month of the year in the Northern Mariana Islands with the average temperatures in the 75°F (23.9°C) to 85°F (29.4°C) range. Steep hills with forest cover and secluded beaches form parts of many islands with volcanic rocks shining in the blazing sun. The paths are safe in the dry season, and the canopy of the jungle offers protection from the intense sun rays. Weather in June »

Weather in July

July is the beginning of the wet season in the Northern Mariana Islands that sees up to 10.2" (259mm) of rain. The average temperatures are in the warm 75°F (23.9°C) to 84°F (28.9°C) range. However, the increased cloud cover and humidity raise the heat index. Weather in July »

Weather in August

August is the wettest month of the year in the Northern Mariana Islands with an average of 12.4" (315mm) of rainfall. It rains cats and dogs, yet there are clear, extended periods of bright sunshine that last up to 5 hours a day. Day temperatures scale up to an average of 84°F (28.9°C), while nights register up to 75°F (23.9°C). Weather in August »

Weather in September

September is hot and humid in the Northern Mariana Islands with daily showers in Saipan, Tinian, and Rota. The average precipitation is 10.7" (272mm) in the month, with periods of heavy rain. The humidity is above 80%, and the average temperatures register between 75°F (23.9°C) and 84°F (28.9°C). Weather in September »

Weather in October

October brings a massive 11" (279mm) of rain in the Northern Mariana Islands, and there is a rare day in the month that does not receive precipitation. The cloudy days limit visibility on the seas, and the slow tourist season affects the cruise business. The average temperatures remain in the range of 75°F (23.9°C) to 84°F (28.9°C) as the conditions remain sticky during both days and nights. Weather in October »

Weather in November

November sees a slight drop in temperatures and precipitation in the Northern Mariana Islands, with partly cloudy skies. The sunshine lasts for 6 hours a day as the rainy season is on its last legs. The average humidity drops below 80%, and the temperatures range between 75°F (23.9°C) to 83°F (28.3°C). Small farms begin to produce coconuts, melons, and breadfruit with the end of the wet season. Weather in November »

Weather in December

December begins the dry season in the Northern Mariana Islands, with the average temperatures in the 74°F (23.3°C) to 81°F (27.2°C) range. The atmosphere cools down a little, but there is hardly a winter season on the islands. Weather in December »
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