New KNMI climate scenarios: hotter St. Maarten, possible major drying, and rising seas that keep coming

GREAT BAY--A new set of climate scenarios developed for St. Maarten warns that the island’s future is set to become significantly hotter, likely drier, and increasingly exposed to coastal flooding as sea level continues to rise beyond this century. The report, produced through collaboration between the Meteorological Department St. Maarten (MDS) and the Royal Netherlands Meteorological Institute (KNMI), is intended to support risk planning and adaptation decisions for 2050 and 2100.

Heat: longer hot seasons, more frequent extreme heat

Based on the scenarios, St. Maarten’s average temperature is projected to be about 0.8°C to 1.3°C higher by 2050, and could reach up to 3.3°C warmer by 2100, with heat lasting longer through the year. The report links rising heat to health risks, particularly for vulnerable groups, and notes that higher temperatures can also drive increased electricity demand for air conditioning.

The scenarios also translate that warming into day-to-day experience, with a sharp increase in “hot days” as the century progresses. Using a definition of hot days as those with average temperatures above 29.5°C, the report projects a jump from about 17 hot days per year now to far higher totals by mid-century and especially by the end of the century in higher-emissions pathways.

Rainfall: a drier future is likely, how dry remains uncertain

The report describes St. Maarten’s rainfall as highly variable year to year, influenced by large-scale drivers such as El Niño and La Niña. That natural variability is expected to continue, but most scenarios point to an overall drying trend, strongest in the high-emission, strong-drying futures where annual rainfall could be reduced by up to about half compared to today.

Uncertainty remains, in part because scientists still debate how El Niño and La Niña patterns may evolve, and because global models do not fully agree on what that means for the Caribbean. In practical terms, the island could see longer dry seasons and added pressure on nature, farming, and water resources, even as some scenarios allow for limited wet-season recovery.

Sea level: 2050 may look manageable, 2100 is much harder, and it does not stop

For coastal St. Maarten, the biggest long-term certainty in the report is sea level rise. Near the island, sea level has already been rising at roughly 3.1 centimeters per decade (1993–2023). Looking ahead, the scenarios indicate about 21 to 23 cm of rise by 2050 relative to a 1995–2014 baseline, and about 46 to 78 cm by 2100 depending on emissions, with higher emissions producing higher seas.

Beyond the 2100 horizon, the report stresses that sea level rise continues for many years even if warming stops, meaning a rise of more than 1 meter is presented as inevitable over the longer term. It also flags low-likelihood, high-impact possibilities tied to potential Antarctic ice-sheet instability, which could produce much higher outcomes by around 2100 in worst-case dynamics, although the report treats these as uncertain and not the central expectation.

Hurricanes and extreme rain: not fully modeled here, but risks still rise

The report is explicit that its core scenario set does not fully model changes in hurricanes or extreme rainfall for St. Maarten, because those require different methods and specialized models. Still, it summarizes the broader scientific picture: even if total annual rainfall decreases, intense downpours can become heavier because warmer air holds more moisture, and hurricanes are expected to become stronger and wetter as ocean temperatures rise.

The report points to KNMI’23 work examining Hurricane Irma in a warmer climate, indicating that the most severe hurricanes are likely to produce stronger winds and significantly more rainfall, raising the stakes for preparedness, drainage capacity, and coastal protection.

What the scenarios are, and why there are multiple futures

Rather than presenting a single forecast, the report uses multiple scenarios to bracket possible futures, based on two big uncertainties: how much the world emits (low, moderate, high emissions), and how rainfall behaves (mild drying versus strong drying). This creates a range that policymakers can use for planning under uncertainty, including a “moderate” pathway the report describes as useful for near-term adaptation planning.

For local detail, the scenarios were statistically downscaled using observational data from the Princess Juliana Airport station, with the report arguing the resulting values are broadly representative for the island even though microclimates can differ by location.

What it means on the ground: water, heat, coastlines, and planning choices

Across the report, the practical message for St. Maarten is that adaptation is no longer optional or distant. Higher heat, longer dry periods, and rising seas are already being felt, and the report highlights priority directions such as protecting water resources, improving infrastructure resilience, and helping communities cope with heat, while recognizing that coastal exposure is a major vulnerability because much infrastructure and housing sit near shorelines.

The file can be downloaded below.

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