Esperanto names weekdays, months, and seasons with regular -o nouns, but the three sets do not behave identically. Weekdays and seasons are ordinary common nouns; traditional month names are treated as proper names. That difference affects capitalization and article use, while case and prepositions still express the temporal role of the whole phrase.
For numbered calendar days rather than the names of time periods, see dates and years.
The days of the week
| Esperanto | English |
|---|---|
| lundo | Monday |
| mardo | Tuesday |
| merkredo | Wednesday |
| ĵaŭdo | Thursday |
| vendredo | Friday |
| sabato | Saturday |
| dimanĉo | Sunday |
Weekday names are common nouns and normally begin with lowercase letters. They can identify the kind of day without an article:
Hodiaŭ estas lundo, kaj morgaŭ estos mardo.
Today is Monday, and tomorrow will be Tuesday.
This differs from English capitalization. Writing Lundo in the middle of a sentence imports an English convention that Esperanto does not need.
A particular weekday used directly as the time of an event commonly takes temporal -n:
Ni veturos al la lago sabaton, se ne pluvos.
We will travel to the lake on Saturday if it doesn't rain.
— Ĉu vi povas telefoni al mi venontan ĵaŭdon? — Jes, mi telefonos post la laboro.
— Can you call me next Thursday? — Yes, I'll call after work.
In venontan ĵaŭdon, the adjective agrees with the understood temporal noun phrase. A preposition can mark a different relation, in which case no temporal -n is added:
La oficejo restos fermita ĝis lundo.
The office will remain closed until Monday.
The article follows normal meaning. Venis la dimanĉo refers to a contextually definite Sunday; Hodiaŭ estas dimanĉo merely classifies today by weekday. Weekday words are sometimes used almost like names without la, but they have not become proper nouns.
Lundon, lunde, and ĉiulunde
Esperanto offers both a temporal noun phrase and an adverb:
- lundon readily points to a particular Monday supplied by context;
- lunde means “on Monday/Mondays” and often suits a schedule or habitual statement;
- ĉiulunde unambiguously means “every Monday.”
La kurso komenciĝos lundon, sed poste ni kunvenos ĉiun merkredon.
The course will begin on Monday, but afterward we will meet every Wednesday.
La apoteko estas fermita dimanĉe.
The pharmacy is closed on Sundays.
Mi laboras hejme ĉiuĵaŭde kaj iras al la oficejo vendrede.
I work from home every Thursday and go to the office on Fridays.
Actual usage allows overlap: lunde can refer to one relevant Monday, and lundon can occur in repeated schedules when the repetition is otherwise clear. The distinction above is a useful tendency, not an absolute grammatical ban.
The months
| 1–6 | 7–12 |
|---|---|
| Januaro | Julio |
| Februaro | Aŭgusto |
| Marto | Septembro |
| Aprilo | Oktobro |
| Majo | Novembro |
| Junio | Decembro |
In the traditional analysis followed by PMEG, month names are proper names. They normally begin with a capital and appear without la: en Majo, de Januaro ĝis Marto.
La nova ekspozicio malfermiĝos en Oktobro.
The new exhibition will open in October.
Ni kutime ferias de la fino de Julio ĝis la mezo de Aŭgusto.
We usually take vacation from the end of July until the middle of August.
The articles in la fino and la mezo belong to those common nouns, not to the month names. Lowercase month names are attested in contemporary lowercase-oriented styles, but capitalization is the clear reference convention here. Derived ordinary words are lowercase: januara numero, aprila vetero, oktobre.
La maja programo estos publikigita fine de Aprilo.
The May program will be published at the end of April.
The day of a month is an ordinal followed by de + month:
La festivalo komenciĝos la dek-sepan de Junio.
The festival will begin on June seventeenth.
Dek-sepan carries temporal -n because the whole date answers “when?”; Junio remains unchanged after de. This is why a literal month-first form modeled on American English is wrong.
The seasons
The four basic season names are ordinary lowercase nouns:
| Esperanto | English | Adverb |
|---|---|---|
| printempo | spring | printempe |
| somero | summer | somere |
| aŭtuno | autumn/fall | aŭtune |
| vintro | winter | vintre |
For a season in general, both en somero and en la somero are possible. The article choice follows the normal contrast between a type of time and a definite period; it is not an irregular calendar rule.
En somero la tagoj estas longaj, sed vintre ili estas multe pli mallongaj.
In summer the days are long, but in winter they are much shorter.
Dum la somero de 2025 ni loĝis apud la maro.
During the summer of 2025, we lived by the sea.
The first sentence speaks generically. The second identifies one specific summer, so la is natural. The adverb form is compact and neutral for general timing:
La migrobirdoj revenas printempe kaj forflugas aŭtune.
The migratory birds return in spring and fly away in autumn.
Exact days versus stretches of time
A weekday or date locates an event. A plural calendar unit can instead measure duration or frequency, and then its case follows the measurement construction.
Ni alvenis vendredon kaj restis tri tagojn.
We arrived on Friday and stayed for three days.
Vendredon is a time point; tri tagojn measures extent. With an explicit preposition, use the prepositional form:
Ni laboros dum tri semajnoj, de lundo ĝis vendredo.
We will work for three weeks, from Monday through Friday.
After dum, de, and ĝis, there is no added temporal -n. The bare cardinal tri also remains invariant; plural belongs on semajnoj.
Calendar units can form transparent compounds and adjectives: semajnfino “weekend,” labortago “workday,” dusemajna vojaĝo “a two-week trip,” vintra mantelo “winter coat.” These describe a kind or duration rather than naming a date.
Ni planas dusemajnan vojaĝon por la venonta printempo.
We are planning a two-week trip for next spring.
International scheduling
When a schedule crosses time zones or cultures, combine an unambiguous date, weekday, and clock time:
La reta seminario okazos merkredon la 14-an de Oktobro je 18:00 UTC.
The online seminar will take place on Wednesday, October 14, at 18:00 UTC.
The weekday and day ordinal both have temporal -n. The month follows de, while the clock time follows je. This exact formatting keeps three different grammatical relations visible.
Common Mistakes
Capitalizing weekdays like English
❌ La vendejo estos fermita Dimanĉon.
Incorrect capitalization — weekday names are common nouns.
✅ La vendejo estos fermita dimanĉon.
The shop will be closed on Sunday.
Adding an article automatically before a month
❌ Ni translokiĝos en la Novembro.
Incorrect in the normal proper-name analysis of month names.
✅ Ni translokiĝos en Novembro.
We will move in November.
Using the wrong form for a one-time weekday
❌ Mi vizitos vin la venonta lundo.
Incorrect as a direct time adjunct — the phrase needs temporal -n.
✅ Mi vizitos vin venontan lundon.
I will visit you next Monday.
Copying English month-first order
❌ La kurso komenciĝas Septembro unua.
Incorrect — Esperanto dates use an ordinal day followed by de plus the month.
✅ La kurso komenciĝas la unuan de Septembro.
The course begins on September first.
Treating a season as a proper name
❌ Ni ofte naĝas en Somero.
Incorrect capitalization — season names are ordinary nouns.
✅ Ni ofte naĝas somere.
We often swim in summer.
Key Takeaways
Write weekdays and seasons in lowercase; use a capital for standalone month names in the reference convention followed here. A specific weekday can take temporal -n, a habitual schedule often favors an -e adverb, and prepositions replace bare temporal case marking. Choose the article by meaning for common-noun seasons, but normally use proper-name months without la.
Related Topics
- Dates and YearsA2 — Form, inflect, write, and read Esperanto calendar dates and years without importing ambiguous English date order.
- Telling Clock TimeA1 — Ask and tell the time in Esperanto with ordinal hours, cardinal minutes, fractions, day-part expressions, and the correct time prepositions.
- Duration and FrequencyA2 — Express how long and how often events occur with measured accusatives, dum-phrases, recurring time expressions, and fojo-based forms.
- Time AdverbsB1 — Place events in time with Esperanto primitive particles and productive -e forms, including precise contrasts such as ĵus, tuj, and lunde.
- Calendar Dates in the AccusativeB1 — Learn why Esperanto calendar dates often take temporal -n, how to write ordinal dates, and when a date correctly remains unmarked.
- The Definite Article LaA1 — How invariant la marks a referent that the listener can identify, and when another determiner or zero article is required.