The Zenith Sun is a weather phenomenon known as Instant Without Shadows. In Spanish it is referred to as “Sol Cenital.” Its presence marks the beginning of the most rigorous heat period for the country. Residents should anticipate a week of suppressive heat, high humidity, and extreme solar radiation. It is a period when the “thermal stress” on the body is at its peak, requiring proactive measures to stay cool and hydrated.
As explained by weather expert Jean Suriel on his Instagram account, the phenomenon occurs because the Dominican Republic is located within the tropics (between the Equator and the Tropic of Cancer). Twice a year, as the Earth’s axial tilt causes the sun’s direct rays to migrate northward toward the Summer Solstice, the sun passes directly overhead at a 90-degree angle.
When the sun reaches the “Zenith”—the highest point in the sky— its rays strike the ground vertically. For a few minutes during the solar noon, vertical objects like posts or bottles will appear to have no shadow because the shadow is cast directly beneath the object itself.
Forecast for the DR: Next 7 days
For the upcoming week, this astronomical event combined with current Caribbean weather patterns will result in the following:
Intensified thermal sensation:
Because the sun is at its shortest distance from a vertical perspective, solar radiation is at its maximum intensity.
• What to expect: Even if the thermometer reads 32°C (90°F), the “RealFeel” or heat index will likely surge to 38°C–42°C (100°F–108°F), especially in urban centers like Santo Domingo and Santiago, and the arid Northwest (Line-a Noroeste).
• Peak Hours: The heat will be most oppressive between 11am and 4pm.
Extreme UV Index:
The UV Index will consistently reach “Extreme” levels (11+). At this angle, the atmosphere provides the least amount of filtration for ultraviolet rays.
• Impact: Skin damage can occur in as little as 10–15 minutes of unprotected exposure. High-quality sun protection and staying hydrated are critical this week.
Convective activity (rain showers):
The intense heating of the land (diurnal heating) caused by the Zenith Sun often triggers “convective” rain, mostly in the afternoon.
• The pattern: Expect clear, scorching mornings followed by the rapid buildup of clouds over the Cordillera Central and Los Haitises. This typically results in sudden, heavy afternoon thunderstorms or “chubascos” that provide temporary relief but increase humidity levels shortly after.
High nighttime temperatures:
The solar intensity during the day means that concrete and asphalt will absorb massive amounts of heat. This energy is released slowly at night, meaning evening temperatures will remain high, rarely dropping below 24°C (75°F) in coastal areas, which can lead to heat exhaustion if indoor spaces are not well-ventilated.
Read more in Spanish:
Jean Suriel
13 May 2026