Temporal Clauses in Welsh

In Brief

Welsh links events in time with pan “when”, cyn “before”, ar ôl “after”, tra “while”, nes “until”, and ers “since”. The essential choice is between a full clause, as in pan fydd hi'n cyrraedd, and a verb-noun pattern, as in cyn mynd or cyn i fi fynd. Watch especially for future forms after pan and soft mutation in patterns with i + subject + verb-noun.

Overview

A temporal clause is simply a part of a sentence that locates one situation in relation to another: “when the bus arrives”, “before we leave”, or “while I was cooking”. It is a dependent clause—a group of words that has a subject and verb but relies on the rest of the sentence to complete the message. In Pan gyrhaeddais i, roedd y drws ar gau, the words Pan gyrhaeddais i tell us when the door was closed.

At B1, these clauses let you move beyond a list of separate events and explain sequence, overlap, duration, and endpoints. The individual connectors are not difficult to remember. The challenge is that Welsh does not always put the same kind of verb structure after each one.

English-speaking learners should pay particular attention to two differences. First, English says “when I am ready” for future time, whereas Welsh commonly uses a future form: pan fydda i'n barod. Second, Welsh often expresses “before/after/since someone did something” with i + subject + verb-noun, rather than with an ordinary tensed verb: ar ôl i ni fwyta “after we ate”. A verb-noun is the basic Welsh verb form, such as mynd “to go/going” or bwyta “to eat/eating”.

How It Works

Choose the pattern from the connector

Connector	Meaning	Usual structure	Example
pan	when, whenever	finite clause	pan fydd y trên yn cyrraedd
cyn	before	verb-noun, or i + subject + verb-noun	cyn gadael; cyn i ni adael
ar ôl	after	verb-noun, or i + subject + verb-noun	ar ôl bwyta; ar ôl i ni fwyta
tra	while	finite clause, often with bod	tra oeddwn i'n aros
nes	until	finite clause or i-clause	nes bydd hi'n barod; nes i bawb gyrraedd
ers	since	time expression or i-clause	ers dydd Llun; ers i fi symud

A finite clause has a verb marked for tense or person: oeddwn i “I was”, bydd hi “she will be”, or cyrhaeddodd e “he arrived”. The other major pattern uses a verb-noun whose time is understood from the connector and the main clause.

Pan: when an event happens

Use pan to place one event or state at the time of another. It is followed by a finite verb phrase:

• pan oeddwn i'n blentyn — when I was a child
• pan gyrhaeddais i — when I arrived
• pan fydd hi'n barod — when she is ready

With a future situation, Welsh normally marks future time inside the pan-clause. This differs from English, which usually uses a present form after “when”.

Welsh	English	Note
Pan fydd y siop yn agor, prynwn ni fara.	When the shop opens, we'll buy bread.	Welsh has future bydd; English has present “opens”.
Pan oedd y plant yn cysgu, roedd y tŷ'n dawel.	When the children were asleep, the house was quiet.	Two past states.
Pan gyrhaeddodd Ceri, dechreuodd y cyfarfod.	When Ceri arrived, the meeting began.	Two completed events.

After pan, an inflected verb commonly undergoes soft mutation—a regular change to its first consonant. Thus cyrhaeddais becomes gyrhaeddais, daeth becomes ddaeth, and gwelais becomes welais. Forms of bod already appear in established combinations such as pan oedd and pan fydd.

Cyn and ar ôl: ordering two events

If the person doing the action is obvious or unimportant, put a verb-noun directly after the connector:

• cyn gadael — before leaving
• cyn dechrau'r gwaith — before starting the work
• ar ôl bwyta — after eating
• ar ôl gorffen — after finishing

When the dependent action has an expressed subject, use this pattern:

cyn / ar ôl + i + subject + soft-mutated verb-noun

Welsh	English	Note
cyn i fi fynd	before I go / went	mynd → fynd
cyn i Ceri dalu	before Ceri pays / paid	talu → dalu
ar ôl i ni fwyta	after we eat / ate	bwyta → fwyta
ar ôl iddo fe gyrraedd	after he arrives / arrived	i + fe appears as iddo fe
ar ôl iddi hi ddechrau	after she starts / started	i + hi appears as iddi hi

The clause itself does not show a separate past or present tense. Context supplies the time. For example, ar ôl i ni fwyta can mean “after we eat” in a future plan or “after we ate” in a past story.

The common personal forms are i mi/i fi, i ti, iddo fe/fo, iddi hi, i ni, i chi, and iddyn nhw. They are part of the Welsh construction; do not translate the i separately. Learn cyn i fi fynd as one pattern meaning “before I go”.

Soft mutation is visible only when the verb-noun begins with an affected consonant. Common changes include mynd → fynd, bwyta → fwyta, dod → ddod, gweld → weld, cyrraedd → gyrraedd, and paratoi → baratoi. A vowel-initial form such as aros has no visible change.

Tra: overlapping situations

Use tra when two actions or states continue at the same time. It normally introduces a clause with its own subject and verb:

• Tra oeddwn i'n coginio, roedd hi'n gosod y bwrdd. — While I was cooking, she was setting the table.
• Tra byddwch chi yma, gallwch chi ddefnyddio'r swyddfa. — While you are here, you can use the office.
• Tra bod y plant yn chwarae, gallwn ni siarad. — While the children are playing, we can talk.

The pattern tra bod + subject is useful for a present or general situation. For a past background, tra oedd... is especially common. Do not put a bare verb-noun straight after tra. If English has “while doing”, Welsh often uses wrth + verb-noun instead: wrth gerdded adref “while walking home”.

Nes: the endpoint

Nes introduces the event that ends a wait, action, or state. A future form is natural when the endpoint has not happened yet:

• Arhoswch nes bydd y golau'n wyrdd. — Wait until the light is green.
• Paid â mynd nes bydda i'n ôl. — Don't go until I am back.

An i-clause can name the person or thing that reaches the endpoint:

• Arhoson ni nes i bawb gyrraedd. — We waited until everyone arrived.
• Doedd hi ddim yn gwybod nes i'r meddyg esbonio. — She did not know until the doctor explained.

Welsh often matches English “not ... until” with ddim ... nes. You may also encounter hyd nes, a fuller form meaning “until”.

Ers: a starting point continuing forward

Ers looks back to the point at which a continuing situation began, or to an event after which things changed. It can introduce a date, day, event, or elapsed period:

• ers 2022 — since 2022
• ers dydd Llun — since Monday
• ers y cyfarfod — since the meeting
• ers tair blynedd — for the last three years

For a clause with a subject, use ers i + subject + verb-noun:

• Dw i wedi byw yma ers i fi ddechrau'r swydd. — I have lived here since I started the job.
• Mae llawer wedi newid ers iddyn nhw adael. — A lot has changed since they left.

English frequently uses the present perfect with “since”. Welsh often has wedi in the main clause too, but the exact main-clause form depends on whether you describe a completed change, an ongoing activity, or a present state. Concentrate first on keeping ers attached to the starting point.

Clause order

The time clause may come before or after the main message:

• Cyn i ti adael, diffodd y golau. — Before you leave, turn off the light.
• Diffodd y golau cyn i ti adael. — Turn off the light before you leave.

A comma after an opening time clause makes a longer sentence easier to read. No comma is usually needed when the time clause comes last.

Examples in Context

Welsh	English	Note
Pan gyrhaeddais i, roedd e wedi mynd.	When I arrived, he had gone.	The earlier action is marked with wedi.
Pan fydda i'n rhydd, bydda i'n dy ffonio di.	When I am free, I'll phone you.	Future form in both clauses.
Pan oedd hi'n bwrw glaw, arhoson ni yn y caffi.	When it was raining, we stayed in the café.	Ongoing past background.
Cyn i fi fynd, rhaid i fi orffen yr adroddiad.	Before I go, I must finish the report.	cyn i fi + fynd.
Golcha dy ddwylo cyn bwyta.	Wash your hands before eating.	The person eating is understood.
Ar ôl bwyta, aethon ni am dro.	After eating, we went for a walk.	One understood subject.
Ar ôl i'r trên gyrraedd, agorodd y drysau.	After the train arrived, the doors opened.	The dependent clause has its own subject.
Tra oeddwn i'n aros, darllenais i bennod arall.	While I was waiting, I read another chapter.	A short event within a longer wait.
Tra bod Aled yn gweithio gartref, mae Mari yn y swyddfa.	While Aled works at home, Mari is in the office.	Simultaneous present arrangement.
Arhoswch yma nes bydd y tacsi'n cyrraedd.	Wait here until the taxi arrives.	Future endpoint.
Wnaethon ni ddim dechrau nes i bawb gyrraedd.	We didn't start until everyone arrived.	ddim ... nes.
Dw i wedi ei hadnabod hi ers i ni fod yn yr ysgol.	I have known her since we were at school.	Starting period introduced by ers.
Mae'r siop ar gau ers dydd Mawrth.	The shop has been closed since Tuesday.	ers + time expression.
Byddwn ni'n yfed coffi ar ôl i ni orffen.	We'll have coffee after we finish.	The time of orffen comes from the future main clause.

Common Mistakes

1. Copying English clause structure after cyn

• Wrong: Cyn dw i'n mynd, rhaid i fi orffen.
• Right: Cyn i fi fynd, rhaid i fi orffen.
• Why: With an expressed subject, use cyn i + subject + verb-noun, not an ordinary present-tense clause.

2. Forgetting soft mutation in an i-clause

• Wrong: Ar ôl i ni bwyta, aethon ni allan.
• Right: Ar ôl i ni fwyta, aethon ni allan.
• Why: The verb-noun is soft-mutated in this construction: bwyta becomes fwyta.

3. Forgetting mutation after pan

• Wrong: Pan bydda i'n barod, bydda i'n galw.
• Right: Pan fydda i'n barod, bydda i'n galw.
• Why: Pan causes soft mutation here, so bydda begins with f.

4. Putting a bare verb-noun after tra

• Wrong: Tra aros am y bws, darllenais i.
• Right: Tra oeddwn i'n aros am y bws, darllenais i.
• Also natural: Wrth aros am y bws, darllenais i.
• Why: Tra normally takes a full clause. Use wrth + verb-noun for “while doing”.

5. Leaving the understood subject unclear

• Unclear: Ar ôl bwyta, dechreuodd y cyfarfod.
• Clear: Ar ôl i ni fwyta, dechreuodd y cyfarfod.
• Why: A bare verb-noun usually invites the reader to connect its action with the main subject. Name the eater when the main subject is “the meeting”.

6. Mixing “since” and “ago” in one phrase

• Wrong: Dw i yma ers tair blynedd yn ôl.
• Right: Dw i yma ers tair blynedd.
• Why: Ers already looks back from now. Do not add yn ôl “ago” to the same time span.

Usage Notes

Spoken and written Welsh do not always choose identical verb forms. A narrative may contain compact forms such as gyrhaeddais i “I arrived” and darllenais i “I read”, while conversation may favour regional forms built with gwneud. The connector patterns remain useful across both styles, even when the chosen past verb changes.

Pronouns also vary. I mi is common in more formal language, while many speakers and courses use i fi; fo is frequent in much of the north and fe in the south. Consequently, you may meet both cyn i mi fynd and cyn i fi fynd, as well as ar ôl iddo fo and ar ôl iddo fe. These are not differences in the time relationship.

For future-time clauses, pan fydd... is a dependable model. Everyday speech can show more variation, but English learners should not automatically copy the English present tense into Welsh. Learn the future connector and future form together: pan fydda i, nes bydd, tra byddwch chi.

Beyond the Basics / Advanced Use

The connector does more than name a point in time; the chosen verb form presents an action as ongoing, completed, or habitual. Aspect is the way a speaker presents the internal shape of an action—whether it is in progress, complete, or repeated.

Welsh	English	Note
Pan oeddwn i'n darllen, canodd y ffôn.	When I was reading, the phone rang.	Ongoing background plus a short event.
Pan ddarllenais i'r neges, deallais i'r broblem.	When I read the message, I understood the problem.	Two completed events.
Ar ôl i fi ddarllen y neges, atebais i.	After I read the message, I replied.	The connector makes the sequence explicit.

English “when” also has two grammatical jobs that Welsh normally keeps separate. Pan introduces a time clause, but pryd asks or reports at what time something happens:

• Pan ddaw hi, byddwn ni'n dechrau. — When she comes, we'll start.
• Pryd bydd hi'n dod? — When will she come?
• Dw i ddim yn gwybod pryd bydd hi'n dod. — I don't know when she will come.

For more precise relationships, you will later meet cyn gynted ag “as soon as”, erbyn i... “by the time...”, and wrth... “while/as (doing)”. Compare tra oeddwn i'n cerdded with wrth gerdded: the first is a full clause with an explicit “I”, while the second packages walking as the circumstances around the main event.

Finally, beware of nes i in colloquial Welsh. In southern varieties, nes i brynu bara can be a past construction meaning “I bought bread”. In a temporal clause, nes means “until”, as in Arhosais nes i'r siop agor “I waited until the shop opened”. The surrounding sentence—and an explicit subject after i—normally makes the meaning clear.

Practice Tips

1. Learn frames, not isolated connectors. Complete six prompts each day: pan fydd..., cyn i fi..., ar ôl i ni..., tra oedd..., nes bydd..., and ers i....
2. Draw a two-event timeline. Put “finish work” and “phone Ceri” in order, then describe it with cyn, ar ôl, and pan. Add two simultaneous actions to practise tra.
3. Drill mutation in useful chunks. Say and write i fynd, i ddod, i weld, i fwyta, i gyrraedd, then place each chunk after cyn, ar ôl, nes, or ers.

Related Concepts

• Prerequisite: Conjunctions and Connectors — introduces basic ways of joining Welsh clauses, including pan.
• Helpful foundation: Verb-Nouns — explains forms such as mynd, aros, and bwyta.
• Helpful foundation: Soft Mutation — supports patterns such as pan fydd and ar ôl i ni fwyta.
• Next step: Bod — Future Tense — develops forms used after pan, tra, and nes for future time.
• Next step: Inflected Verb Forms — helps with narrative forms such as gyrhaeddais and darllenais.