Spanish Months: Capitalization Rules Explained

No, the months are not capitalized in Spanish. Write enero, febrero, marzo and so on in lowercase, including in dates: el 5 de mayo de 2025. You use a capital only when the month is the first word of a sentence or a title, or when it is part of a proper name such as a holiday, a historical event or a street: el Dos de Mayo, la avenida 9 de Julio.

The months in Spanish

Abbreviations are lowercase too, with a full stop: 15 ene. 2025. Capitals appear only in all-caps formats such as calendar headers or forms (ENE, FEB). All months are masculine: un enero frío, el pasado agosto.

The rule and its exceptions

Lowercase: the normal case

• Mi cumpleaños es en abril. – My birthday is in April.
• Las clases empiezan en septiembre. – Classes start in September.
• Nos vemos a principios de enero. – See you at the beginning of January.
• Hace mucho calor en julio y agosto. – It’s very hot in July and August.
• Diciembre es mi mes favorito. – December is my favourite month. (capital only because it starts the sentence)

This rule comes from the Real Academia Española and the other Spanish language academies, and it is the same in Spain and Latin America. The days of the week follow it too: lunes, martes, domingo. Seasons as well: primavera, verano, otoño, invierno.

1. First word of a sentence

Any word that opens a sentence takes a capital: Marzo fue muy lluvioso. (March was very rainy.) Inside the sentence, it goes back to lowercase.

2. Titles: only the first word

Spanish titles capitalize only the first word and proper names, not every important word as English does. So a month in the middle of a title stays lowercase:

• Los días de enero (not Los Días de Enero)
• Agosto en la ciudad (capital because it is the first word)
• Informe de ventas de marzo

Some magazines and websites copy English title case, but it is not standard Spanish.

3. Part of a proper name

When a date has become the name of a holiday, an event, a street, a square or an institution, it is capitalized as a whole:

But a plain date stays lowercase even if a holiday falls on it: La Navidad es el 25 de diciembre. El Día de la Independencia de México es el 16 de septiembre. The holiday name is capitalized; the month in the date is not.

Writing dates

Dates are where English speakers slip most often, because the English habit of a capital letter is strong.

The order is day + de + month + de + year, with the month in lowercase:

• el 3 de marzo de 2024 – 3 March 2024 / March 3, 2024
• el 1 de enero or el primero de enero – 1 January (primero is common in Latin America; Spain usually says uno)
• Madrid, 12 de octubre de 2025 – heading of a letter
• ¿Qué fecha es hoy? – Es el 20 de junio. – What’s the date today? – It’s 20 June.
• Nació en noviembre de 1998. – She was born in November 1998.

In numbers, the day comes first: 3/3/2024 or 03-03-2024. 5/7 means 5 July, not May 7. From 2000 on, the academies recommend de before the year (de 2025), though del 2025 is also common in speech.

Useful phrases with months

Prepositions with months

• en for “in”: en mayo. Not en el mayo, unless you add a description: en el mayo más lluvioso que recuerdo (in the rainiest May I can remember).
• de in dates and “of”: el 2 de mayo, el mes de mayo, la factura de mayo (May’s bill).
• para for deadlines: Lo necesito para marzo. (I need it by March.)
• hasta for “until”: Estoy de vacaciones hasta julio.
• desde for “since/from”: Trabajo aquí desde enero. (I’ve worked here since January.)
• a partir de for “starting from”: El nuevo horario empieza a partir de octubre.

Months and seasons

Seasons are lowercase too, and they depend on the hemisphere. In Spain and Mexico, diciembre, enero and febrero are winter months. In Argentina, Chile and Uruguay they are the summer holidays, and julio is the middle of winter:

• En España, el verano va de junio a septiembre. – In Spain, summer runs from June to September.
• En Buenos Aires hace frío en julio. – It’s cold in Buenos Aires in July.
• Las vacaciones de invierno en Chile son en julio. – Winter holidays in Chile are in July.

Talking about birthdays and plans

• ¿Cuándo es tu cumpleaños? – Es el 14 de febrero. – When is your birthday? – It’s 14 February.
• Me mudo en noviembre. – I’m moving in November.
• El curso dura de octubre a junio. – The course runs from October to June.
• Pago el alquiler el primer día de cada mes. – I pay the rent on the first of every month.
• La oferta es válida hasta el 31 de agosto. – The offer is valid until 31 August.

English vs Spanish capitalization at a glance

For the full set of rules, see Spanish capitalization rules; for weekdays, see days of the week in Spanish.

Common mistakes

Practice

Correct the capitalization, or write “correcto”.

1. Nos casamos en Junio.
2. Octubre es el mes de Halloween.
3. La reunión es el 2 de Febrero.
4. Vivo en la calle 18 de julio, en Montevideo.
5. El libro se titula “Un Verano en Diciembre”.
6. La Navidad es en diciembre.

Answers: 1. junio 2. correcto (first word) 3. febrero 4. calle 18 de Julio (part of the street’s name) 5. “Un verano en diciembre” 6. correcto

Translate. a) School starts in September. b) I was born on 8 March 2001. c) See you at the end of the month.

Answers: a) Las clases empiezan en septiembre. b) Nací el 8 de marzo de 2001. c) Nos vemos a finales de mes.

Quick answers

Are months of the year capitalized in Spanish?

No. They are common nouns and are written in lowercase except at the start of a sentence or title, or inside a proper name.

Was there a time when months were capitalized in Spanish?

Yes. Older texts often capitalized them, and you can still see this in old documents and some official letters. Current academy rules call for lowercase.

Is it septiembre or setiembre?

Both are accepted. Septiembre is far more common; setiembre is used in some countries, such as Uruguay and Peru.

Do I capitalize the month in an email date or a form?

No. Write Sevilla, 3 de abril de 2025 at the top of a letter or email, and Fecha: 3 de abril de 2025 on a form. Only forms printed entirely in capitals use ABRIL.

Is it en el mes de mayo or en mayo?

Both are correct. En mayo is the everyday choice; en el mes de mayo is a little more formal or emphatic. The month is lowercase either way.

Is “Cinco de Mayo” capitalized?

Yes, when it names the holiday: celebramos el Cinco de Mayo. As a plain date it is lowercase: la reunión es el cinco de mayo.

Are days of the week capitalized in Spanish?

No, the same rule applies: el lunes, los viernes.