Months in Portuguese: janeiro to dezembro, IPA and date rules

Lower case: what the 1990 Orthographic Agreement says

The Portuguese Language Orthographic Agreement of 1990 settles the question in its Base XIX. The small initial letter is used for the names of days, months and seasons, and the text gives outubro as one of its own examples. Brazil and Portugal therefore write em março, a 5 de outubro, with a small m and o.

Capitalised forms such as Janeiro and Outubro are still met in older printed texts, and the months in many languages table on this site writes the Portuguese row in lower case, as the agreement requires. Under the 1990 rules those capitals are not standard. A capital remains correct at the start of a sentence.

One letter needs attention: março keeps its cedilla, which gives the c an s-sound before o. Without it the word would read with a k-sound.

From Latin to Portuguese

All twelve months in Portuguese come straight from Latin through Old Galician-Portuguese, according to Wiktionary's etymologies: janeiro from Iānuārius, março from mārtius, the month of Mars, junho from iūnius, named after Juno. The changes are regular sound changes of the language. Latin -ārius became -eiro, the shared ending of janeiro and fevereiro; Latin li and ni before a vowel became lh and nh, as in julho and junho.

Fevereiro shows a step of its own: Wiktionary traces it through Late Latin Febrārius, a form without the u of Classical Februārius, and Old Galician-Portuguese spellings such as fevreyro. Agosto comes from Vulgar Latin agustus, so the au of Augustus had already turned to a before Portuguese existed. Spanish shares many of these steps, and the months in Spanish page shows how close the two sets are.

Writing dates with the months in Portuguese

A Portuguese date puts the day first and joins the parts with de: 28 de outubro de 2026. That is the long date pattern in Unicode CLDR for both Brazilian and European Portuguese, and a weekday in front gives the full form, quarta-feira, 28 de outubro de 2026. The first day of a month is usually written as an ordinal, 1.º de janeiro, while the other days use cardinal numbers.

In numbers, both countries write day, month, year with slashes: 28/10/2026. CLDR's short pattern for Portugal shortens the year to two digits, 28/10/26, and its medium pattern for Portugal uses the same slashed form, while Brazil's medium form writes the month as an abbreviation, 28 de out. de 2026.

In a month is em: em janeiro, em agosto. Months take no article in this use.

Brazilian and European pronunciation

The month names are spelled the same everywhere Portuguese is official, from Brazil and Portugal to Angola, Mozambique and East Timor; pronunciation is where they part. European Portuguese reduces unstressed e to a short ɨ, so setembro, novembro and dezembro start with sɨ-, nu- and dɨ-. Brazilian Portuguese keeps a clear e and o.

The r before a consonant in março is a guttural ʁ or h in much of Brazil and a tapped ɾ in Portugal. The final l of abril becomes a w in Brazil, abriw, and stays a dark l in Portugal. And the s before a consonant in agosto is s in most of Brazil but sh in Portugal and in Rio de Janeiro, as Wiktionary's separate Rio transcription shows.

Common mistakes with the months in Portuguese

Writing the months in Portuguese with a capital is the habit English speakers bring along, and the older capitalised spelling keeps it alive in print. In current spelling, Janeiro in mid-sentence is an error.

The second mistake is the preposition. A date takes de between its parts, 5 de maio, never 5 maio, and the English order May 5 has no Portuguese equivalent. For in a month, em is the choice: em julho. Speakers of Spanish should watch three spellings that differ from their own: julho and junho with lh and nh, and março with ç.