docs: document TZ=UTC default for wrangler dev local runtime#30527
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Local Workers development now runs with TZ=UTC to match the production Cloudflare runtime (cloudflare/workers-sdk#13776, closes cloudflare/workers-sdk#8106). Document the new default in two places: - Add a bullet to the Defaults list on the Development & testing page. - Add a Note callout under `wrangler dev` on the Workers commands page.
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This pull request requires reviews from CODEOWNERS as it changes files that match the following patterns:
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@petebacondarwin I feel like the comment on the changelog is wrong here? We probably should have a changelog to alert people given this is a bugfix but a possible breaking change? |
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I don't actually believe that this has any breaking change concerns. We haven't come up with any scenario where this bug fix would actually break anyone. I think it was us just being a bit over cautious when first considering this change. |
penalosa
approved these changes
May 7, 2026
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Summary
Documents the new
TZ=UTCdefault for the local Workers runtime, introduced in cloudflare/workers-sdk#13776 (closes cloudflare/workers-sdk#8106).Cloudflare's production runtime runs Workers with
TZ=UTC, but Miniflare previously inherited the host machine's timezone, causing dev/prod drift inDateandIntlbehaviour. Local development now matches production by default — this PR updates the docs to reflect that.Two small additions:
:::notecallout underwrangler devon the Workers commands page.Documentation checklist