textproduct: San Juan

KEY MESSAGES

Issued at 228 PM AST Thu Jul 16 2026

* Showers and isolated thunderstorms are expected this afternoon across central and western Puerto Rico as a weak trade wind perturbation continues to moves across the region. Localized ponding of water on roads and in poor drainage areas is possible, but widespread flooding is not expected.

* Low to moderate concentrations of Saharan dust concentrations will return on Friday, resulting in hazy skies and poor air quality through early next week.

* Hot and humid conditions are expected through Friday across urban and coastal areas, posing mostly limited heat risk, especially for those sensitive to heat or spending extended periods outdoors without adequate hydration or access to cooling.

* A low risk of rip currents will continue today across the beaches of Puerto Rico and the U.S. Virgin Islands.

Short Term(This evening through Saturday)

Issued at 228 PM AST Thu Jul 16 2026

Calm weather conditions prevailed this morning across Puerto Rico and the U.S. Virgin Islands. By mid-morning, moisture from a weak trade wind perturbation began moving over the U.S. Virgin Islands, bringing passing showers to St. Croix and the Anegada Passage. Later in the afternoon, isolated showers developed across eastern Puerto Rico, resulting in minimal accumulations. Daytime temperatures reached into the upper 80s to low 90s across coastal and urban areas, while higher elevations remained in the low to mid-80s. Luis Munoz Marin International Airport in San Juan reported a maximum temperature of 90F by early afternoon. Winds prevailed from the east at 15 to 20 mph, with higher gusts and local sea breeze variations.

For the remainder of the afternoon, central and western Puerto Rico can expect developing showers and isolated thunderstorms. This localized activity could trigger minor urban and small-stream flooding, especially in areas with poor drainage.

A Tropical Upper Tropospheric Trough (TUTT) located over the northeastern Caribbean is forecast to linger through early Friday, keeping the upper levels somewhat unstable. A similar weather pattern is anticipated for Friday as steady trade winds persist. However, as the TUTT gradually lifts northward and away from the region, atmospheric instability will diminish. This will allow drier air to filter in, limiting activity primarily to passing morning showers followed by isolated afternoon convection over western Puerto Rico. By the weekend, this drier and more stable air mass will continue to spread across the islands, leading to mostly fair weather conditions with minimal shower activity. A low to moderate concentration of Saharan dust is also expected to return, resulting in hazy skies, reduced visibilities, and lower air quality. As a reminder, sensitive groups, particularly those with respiratory ailments or allergies, should take necessary precautions and limit prolonged outdoor exposure.

Long Term(Sunday through next Wednesday)

Issued at 228 PM AST Thu Jul 16 2026

A generally quiet and relatively dry weather pattern is expected through the weekend into early next week. Patches of low-level moisture will support passing showers, while lingering moisture will favor limited afternoon convection, mainly over western Puerto Rico. Relatively dry mid-level conditions should limit organized or widespread rainfall. Moderate to high concentrations of Saharan dust are also expected around Sunday into Monday.

Conditions may gradually become more favorable for increased convective activity by the middle to latter part of next week as a series of upper-level lows and troughs promote cooling aloft, the trade wind cap weakens, and moisture potentially extends deeper into the atmosphere. However, confidence in this transition remains low, and no significant rainfall event is apparent at this time. Winds should gradually weaken toward midweek before increasing again later in the week.

Warm conditions will persist, with above-normal low-level temperatures and sufficient moisture continuing to support elevated heat concerns.

AVIATION

(18Z TAFS) Issued at 228 PM AST Thu Jul 16 2026

Mainly VFR conds will prevail at all TAF sites thru the fcst period. A weak atmospheric perturbation will bring SHRA portions of the islands, resulting in VCSH at most terminals and VCTS affecting mainly TJBQ thru 16/23Z. Brief MVFR cigs/vsbys are psbl in heavier SHRA/TSRA, but overall mostly localized activity. ESE winds at 15-20 kt with gusts up to 25 kt thru 16/23Z, then diminishing to 5-10 kt thru 17/14Z.

MARINE

Issued at 228 PM AST Thu Jul 16 2026

A surface high over the central Atlantic continues to interact with the PanamaColombia Low, maintaining moderate to locally fresh east to east-southeast winds and moderate to choppy seas through the rest of the workweek and into the weekend. Saharan Dust concentrations have lowered today and should linger for the rest of the week, though another plume may reach the local area by Sunday into Monday, resulting once again in hazy skies and locally reduced visibility. The trade wind perturbation will continue to move across the region this afternoon, with showers and isolated thunderstorms moving across the regional waters and Caribbean Passages.

BEACH FORECAST

Issued at 228 PM AST Thu Jul 16 2026

The beach forecast remains on track. The low risk of rip current continues across the beaches of Puerto Rico and the U.S. Virgin Islands, though beachgoers should be aware of the possibility of isolated life-threatening rip currents near groins, jetties, reefs, and piers. The latest model guidance suggests winds will likely strengthen over the next few days, with the risk of rip currents upgrading to moderate and increasing chance of life-threatening rip currents across most beaches of the islands. The risk should remain moderate through this weekend and possibly early next week. Besides rip currents, beachgoers visiting the western beaches of Puerto Rico should remain weather alert due to showers and isolated thunderstorms that may move over coastal areas, particularly this afternoon. Although concentrations of Saharan Dust have diminished, another plume may move and spread across the region early next week, bringing hazy skies and deteriorating air quality. Sensitive groups must follow medical recommendations.

FIRE WEATHER

Issued at 228 PM AST Thu Jul 16 2026

Elevated fire weather conditions are expected to persist across portions of Puerto Rico today, particularly across the southern coastal plains. Although low-level moisture is forecast to gradually increase later today as a weak trade wind perturbation moves across the region, relative humidity values are still expected to fall to critical levels by late morning and around midday before the deeper moisture arrives. Breezy easterly winds will persist, with sustained speeds of 10 to 20 mph and higher gusts, promoting favorable conditions for rapid fire spread.

Recent observations indicate that most RAWS stations continue to report Keetch-Byram Drought Index (KBDI) values above 700, while 30- day rainfall percentages remain well below normal, generally less than 10 percent and locally below 5 percent across the southern coastal plains. These critically dry fuels, combined with low relative humidity and breezy conditions, will continue to support an elevated fire danger risk. Consequently, another Fire Danger Statement (RFD) will be issued today, primarily for the southern coastal plains of Puerto Rico, where the potential for rapid fire growth will remain the greatest.

SJU WATCHES/WARNINGS/ADVISORIES

PR...None. VI...None. AM...None.