The climatological spring and the third month of the year began this Wednesday in mainland Portugal with a yellow warning for cold weather, but mostly stable and sunny. Will the weather stay true to the saying “it rains every day in March”? Check the forecast!
March 2023 began this Wednesday (1) with yellow warning for cold weather in 17 of the 18 districts of mainland Portugal and should remain so at least until Friday, the 3rd. In addition to the icy environment, with temperatures well below normal for the time of year (negative temperature anomaly and persistently low minimum temperatures), anticyclonic weather prevails, that is, stable, generally dry and mostly sunny, although interspersed with some clouds.
However, the weather pattern should change very soon. Between Sunday (5th) and Monday (6th), the zonal westerly flow (westerly winds) and the polar jet stream are expected to impose themselves, which, being more dynamic and wavy, could allow more fronts associated with Atlantic depressions to arrive in our latitudes.
What is the climatology of March in continental Portugal?
The month of March in continental Portugal, according to the observed history of the climatological normal reference (1971-2000), is only the eighth wettest month in our geography, placing it in the second half of the table regarding the average accumulated precipitation of the twelve months of the year. However, this average does not reveal the important regional contrasts that exist at the national level.
If, on the one hand, there is generally a humid northwest, with an average total rainfall of over 100 mm in the main meteorological stations of the districts of Viana do Castelo, Braga and Porto, on the other hand, it appears that a large part of the country has an average accumulated rainfall value between 50 and 85 mm. Below 50 mm are several other districts, scattered a little over the country, clearly highlighting the districts of Castelo Branco (36.9 mm) and Faro (34.9 mm) as the driest.
Dentro de poucos dias o jato polar voltará a impor-se 💨💪
Deste modo, as depressões atlânticas ganharão protagonismo 🌀, deslocando-se de oeste para leste. Possivelmente alguma surgirá ⛈️ sobre #Portugal continental.
— Meteored | Tempo.pt (@MeteoredPT) March 1, 2023
In terms of temperature, there is an interesting pattern of contrast between the coastal regions, with milder values and a smaller average daily temperature range, and the inland regions, with more extreme values and a greater daily temperature range. The average maximum generally varies between 16 ºC and 18 ºC on the coast and between 14 ºC and 18 ºC in the interior. Highlight also to the average minimum: the lowest value is usually registered in the Northeast Transmontano (2.9 ºC) and the highest in Lisbon, the capital of Portugal (10.4 ºC).
Will March be a prolongation of winter weather or a manifestation of spring warmth?
According to our Monthly Forecast Maps prepared at the Meteorological Department, March 2023 is not expected to show any statistically significant temperature anomaly in continental Portugal in the general set of weeks that comprise it. This is also true for the Autonomous Regions of the Azores and Madeira.
The absence of anomalies is manifested by the existence of maps of national territories colored in gray. Thus, this year, the month of March should present temperature values fully in line with the climatological reference normal.
A rainy month is forecast for mainland Portugal, Madeira and part of the Azores.
The forecast that we run at Meteored highlights that March 2023 will be a very rainy month from north to south in continental Portugal. According to the first projections, the 31-day period ahead will record above-average rainfall in all regions of our country.
The Madeira Archipelago is also expected to record a positive rainfall anomaly (between 5 and 30 mm above normal, especially in the western half of the island).
The positive rainfall anomaly in March is expected to be distributed as follows: between 10 and 20 mm above normal, roughly in the regions of Lisbon and Tagus Valley, Alentejo and Algarve, and parts of Northeast Transmontano and Beira Alta.
Between 20 and 30 mm in parts of the north and center of the country, such as the eastern part of the districts of Vila Real, northwest of the district of Bragança, center-east of the district of Viseu, southwest of the district of Guarda, almost all of Beira Baixa, northern areas of the districts of Leiria, Santarém and Portalegre, west of the region of Coimbra and southwest of the region of Aveiro.
Between 30 and 50 mm, west of the condensation barrier – roughly northwestern Portugal (but also in central points such as the interior of Aveiro and Conimbricense) – for the regions of Alto and Baixo Minho, Área Metropolitana do Porto, Alto Tâmega e Douro and Viseu Dão-Lafões.
For the Azores archipelago, March is expected to be within the normal rainfall range in the Western Group, as well as on the islands of Graciosa and Terceira in the Central Group. Faial is expected to have a wetter-than-normal March, as well as a large part of the island of Pico (western half) and a small part of the western part of the island of Sao Jorge in the Eastern Group.
The western half of Sao Miguel Island is also expected to be wetter than usual, as are some of the islands in the Central Group. In all of these island areas, rainfall anomalies may be positive and similar (5 to 10 mm). Finally, the island of Santa Maria is expected to record rainfall levels within the norm, as are Graciosa, Terceira, Corvo and Flores.
Reliability of long-term predictions
We all know how uncertain long-term forecasts can be, so we recommend that you look at them as trends rather than certainties. Furthermore, since March is the first month of climatological spring – a season that is already extremely variable from a meteorological point of view – it has this added complication (being the first month of this quarterly period of March, April and May), which can lead to chaos in terms of weather forecasting, as it represents the always dynamic transition between winter and spring in the northern hemisphere.