Weekly Forecast

Forecast Discussion

UPDATED: May-26-2026 8:00pm

Key Messages:

• Marine conditions improving from this evening and deteriorating again towards the end of the period.
• Isolated showers with possible thunder especially overnight into the early morning as moisture lingers over the western Caribbean, with a decrease in the chance from Sunday morning.

Nowcast (Tonight):

Abrupt and locally heavy showers occurred this morning across Grand Cayman with 8.6mm reported at the ORIA terminal as a result of moisture and convergence along the periphery of a high-pressure system being enhanced by a weak short-wave trough in the Bay of Honduras. Cloudy conditions have prevailed across Grand Cayman as a result of this moisture remaining stagnant in the Bay, with satellite analysis denoting ~52-55mm of precipitable water in this region and with the position of the aforementioned trough, outbreaks of high level clouds - predominantly cirrostratus - have lingered over GCM most of this afternoon with occasional patches moving towards the Sister Islands whilst gradually dissipating. Throughout this evening, generally cloudy conditions are expected to linger as a result of this elevated moisture interacting with another short-wave trough moving through the Bay tonight with shower chances remaining very low at first as a result of a more stable mid-level remains in place due to areas of subsidence from a trough over the northwest Caribbean. As a result of this shortwave trough in the Bay, model guidance has been suggesting that a localized area of diffluence created by this may become positioned over GCM this evening, once again allowing for some scattered showers and thunderstorms to pop up after midnight through the morning period on Wednesday, some of which may become locally heavy. QPF values throughout this evening remain below warning thresholds as the highest density of shower activity is expected to remain west of the Cayman area with guidance suggesting that another 1/4 inch is likely and isolated areas seeing as much as a 1/2 inch tonight. As a result of the area of high-pressure building and moving further south and east, the pressure gradient over the northwest Caribbean will continue to remain elevated through tonight and the short-term, bringing fresh to locally strong winds and occasional gusty conditions reaching 25 knots possible. Models have maintained that winds above the boundary layer remain to be ~20 - 25 knots this evening, bringing surface winds closer to that of 15 - 20 knots in exposed areas. Seas will remain higher than initially forecast, becoming rougher at times, with guidance suggesting seas rising to around 6 - 7 feet and reaching the low-end of the warning threshold of a Small Craft Alert.   

Short Term Forecast (Thursday through Saturday):

The low levels appear moisture for the period, mostly below 850mb, with isolated showers expected especially overnight and into the early morning. Additionally, supporting partly cloudy to cloudy skies. The mid-levels remain less moist for the period, limiting the chance for deep convection. However, some afternoon isolated thunder is possible due to day-time heating. Higher concentrations of precipitable water is seen to be accumulating along the eastern coast of Honduras moving north to the Yucatan, with a low chance of this moisture drifting east towards the Cayman area. Rainfall accumulation is expected to be about 5mm per day. The low-levels indicate the ridge of high pressure remaining over the northwest Caribbean supporting southeasterly winds. However, as the associated high pressure system over the Atlantic Ocean temporarily slightly weakens, moderate winds are expected from Thursday evening through Friday, with winds picking up again by Saturday morning. The mid and upper-levels only indicate a ridge over the Cayman area with no source of vertical support, and a sharp trough lingering over the western Gulf of Mexico. Seas are expected to slightly improve from Thursday, with moderate to rough seas expected through Friday with moderate seas by Saturday, as greater wave heights retreat southeast of the Cayman area.

Long Term Forecast (Sunday and Monday):

The atmosphere becoming drier in the low to mid levels, especially from Sunday morning, indicating a lesser chance in the development of deep convection. Therefore, a lower chance of isolated showers with thunder, along with the chance of fair to partly cloudy skies is expected for the period. Fresh to locally strong southeasterly winds are expected by Sunday and are expected to last through the period. Moderate to rough seas can be expected in response to the increase in winds. 

Marine Forecast:

Rough seas with wave heights of 5 to 7 ft are expected tonight through Thursday afternoon. A Small Craft Alert is in effect. A temporary improvement in sea conditions is expected from Thursday evening, supporting moderate to rough seas with wave heights of 4 to 6 ft through Friday in which there will be a downgrade to a Small Craft Advisory, and moderate seas by Saturday as greater wave heights retreat southeast of the Cayman area. In response to fresh to locally strong winds expected from Sunday, moderate to rough seas will warrant again a Small Craft Advisory for Sunday through Monday.  
A Small Craft Advisory/Alert means small craft should exercise caution over open waters, especially along the north and east coasts. Within the reef and sheltered areas, conditions may be generally less severe in open waters, but operators should continue to exercise discretion as localized choppy conditions may still develop.

Forecaster: Forbes