Spring starts this Monday, March 20th, at 21:24, throughout the Northern Hemisphere.
At that time, our planet again reaches one of the two points in its orbit where the Sun is aligned with the plane of the Earth's equator, equally illuminating both hemispheres (north and south) of this planet.
This ephemeris is called the Spring Equinox because, from this moment on, the Sun is seen above the celestial equator (projection of the terrestrial equator in the sky) starting Spring in our country.
Contrary to what one might assume, this is not the day when day and night are of equal duration, which happened three days earlier.
This is a consequence of atmospheric refraction, which makes us see the Sun slightly above its true position, thus shortening the duration of the nights.
According to weather forecasts (already confirmed), spring begins with generally cloudy skies and temperatures ranging between 17 and 24 degrees Celsius in mainland Portugal.
The forecasts of the Portuguese Institute of the Sea and the Atmosphere (IPMA) for this first day of Spring are, for mainland Portugal, of a generally cloudy sky, becoming very cloudy in Minho and Douro Litoral at the end of the day.
Light to moderate wind is also expected from the east quadrant, turning to the west quadrant from the afternoon onwards, and morning mist or fog in some places, especially on the west coast.
Forecasts point to a slight rise in temperature.
The minimum temperatures will fluctuate between 4 degrees Celsius (in Bragança) and 12 (in Faro) and the maximum between 17 (in Viana do Castelo) and 24 (in Évora and Beja).
For the Madeira archipelago, generally very cloudy skies are forecast, temporarily decreasing cloudiness during the afternoon, and the possibility of light showers, especially on the northern slopes and in the highlands and until late morning.
Light to moderate northeast wind is also expected, sometimes blowing strongly in the highlands and in the east and west ends of the island of Madeira, especially from the afternoon onwards.
In the Azores, for the western (Flores and Corvo) and central (S. Jorge, Faial, Pico, Graciosa and Terceira) groups, the IPMA predicts periods of very cloudy skies with good openings, light rain or drizzle from the afternoon, favorable conditions to the formation of mists and fair to moderate westerly wind.
In the eastern group (S. Miguel and Santa Maria) the forecast points to periods of very cloudy skies with good openings and fair to moderate west wind, turning southwest towards the end of the day.
On the 21st of June, Spring gives way to Summer.
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