Climate and monthly weather forecast
Northern Mariana Islands, USA

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 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 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.

Spring in the Northern Mariana Islands, falling between March and May, is marked by a continuation of the dry season, with temperatures averaging from 75°F (23.9°C) to 83°F (28.3°C). The relative humidity is less, allowing outdoor activities to be enjoyable. The northeasterly trade winds keep the climate comfortable, and the sunshine is consistent. However, visitor numbers peak during April and May, coinciding with Japanese national holidays.

The summer season from June to August is part of the wet period in the Northern Mariana Islands. June experiences the highest temperatures of the year, averaging from 83°F (28.3°C) to 85°F (29.4°C). Rainfall starts to increase, and the chance of typhoons grows, especially towards August. The humidity also begins to rise, making the heat feel more oppressive. Despite the increased precipitation, the islands remain lush and vibrant.

Autumn months, from September to November, bring the rainiest period to the Northern Mariana Islands. Over fifty% of the yearly precipitation falls during these months, particularly on the southernmost three islands. Wind speeds remain below an average speed of 20mph (32.2km/h), but typhoons present a significant threat. Cloud cover increases, along with humidity, making the overall weather conditions less favorable.

Winter, lasting from December to February, is the driest and most pleasant season in the Northern Mariana Islands. Temperatures are cooler, ranging from 72°F (22.2°C) to 75°F (23.9°C). The rainfall is significantly reduced, contributing only one-third of the annual rainfall. Days and nights are roughly equal in duration, and the trade winds help drive away clouds, leaving clear skies. This season is considered the best time to visit, providing the most comfortable climate for outdoor activities and exploration.

January falls in the dry season of the Northern Mariana Islands and is part of the most pleasant time of the year for the region. This month does not experience notable extremes in temperature or precipitation. The islands do not have significant variations in climate among different cities, given the general uniformity of weather patterns across the territory. Compared to December, January maintains similar weather characteristics, with temperatures ranging from 72°F (22.2°C) to 75°F (23.9°C). Weather in January »

February continues the dry and favorable weather trend in the Northern Mariana Islands. It represents one of the coldest months of the year, although temperatures are far from extreme. The consistent climate across the islands leads to a lack of notable weather variations among the cities within the territory. The temperatures in February maintain a comfortable range, slightly cooler than in January, with values from 72°F (22.2°C) to 75°F (23.9°C). Weather in February »

March marks a transitional phase in the Northern Mariana Islands, where the weather begins to shift towards the warmer part of the dry season. The consistency of the climate is maintained across the islands, without any remarkable variations among different locations within the territory. In March, the temperatures exhibit a slight increase compared to the previous months, ranging from 73°F (22.8°C) to 81°F (27.2°C). Weather in March »

April in the Northern Mariana Islands sees a continuation of the dry season, with temperatures slightly warmer than the previous month. The weather pattern remains uniform across the islands, and there is no significant distinction in climate among various locations. Temperatures in April are from 75°F (23.9°C) to 83°F (28.3°C), representing a gradual increase as the islands move towards the warmer half of the year. Weather in April »

May signals a shift in weather patterns as the Northern Mariana Islands approach the cusp of the wet season. Despite the proximity to the wetter months, the weather remains relatively consistent across different locations within the territory. The temperature in May ranges from 77°F (25°C) to 85°F (29.4°C), representing one of the warmer periods of the year. Weather in May »

June in the Northern Mariana Islands marks a significant transition as the islands brace for the onset of the wet season. The climate remains consistent across the islands, and no substantial variations exist among different locations. Temperatures in June range from 80°F (26.7°C) to 85°F (29.4°C), with this month typically registering the highest temperatures of the year. Weather in June »

July represents the onset of the wet season in the Northern Mariana Islands, bringing about a substantial shift in weather patterns across the territory. There are no significant variations in climate among different locations on the islands. Temperatures in July continue to be warm, ranging from 83°F (28.3°C) to 85°F (29.4°C), maintaining similar levels to June. Weather in July »

August in the Northern Mariana Islands is characterized by the peak of the wet season, with substantial rainfall and a possibility of typhoons. The climate remains fairly consistent across the different locations within the territory, but the weather takes on a more pronounced tropical character. Temperatures in August are from 83°F (28.3°C) to 85°F (29.4°C), maintaining a warm and consistent range as in the previous month. Weather in August »

September in the Northern Mariana Islands continues to be dominated by the wet season, exhibiting weather patterns consistent with the preceding months of heavy rainfall. There are no notable variations in climate among the different locations within the islands. Temperatures in September range from 83°F (28.3°C) to 85°F (29.4°C), remaining consistent with the temperatures in August. Weather in September »

October in the Northern Mariana Islands signifies a gradual transition towards the end of the wet season. The weather remains consistent throughout the territory, maintaining the tropical rainforest climate that defines the islands. Temperatures in October remain warm, ranging from 80°F (26.7°C) to 85°F (29.4°C), showing little variation from the preceding months. Weather in October »

November in the Northern Mariana Islands marks a significant shift towards the dry season, as the weather patterns begin to stabilize and the wet season's intense rainfall subsides. Consistency in climate persists across the islands, with no remarkable variations between different locations. Temperatures during November are between 75°F (23.9°C) and 85°F (29.4°C), offering a warm yet gradually cooling trend as the islands move further from the wet season. Weather in November »

December in the Northern Mariana Islands welcomes the dry season, characterized by more moderate rainfall and stable weather conditions throughout the territory. The islands maintain a consistency in climate, devoid of major variations in weather among different locations. Temperatures in December range from 72°F (22.2°C) to 75°F (23.9°C), marking the beginning of the coldest period of the year in the Northern Mariana Islands. Weather in December »