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Head to head · Weather current · October 2026 research run

Tomorrow.io Weather API vs Xweather Weather API

Xweather Weather API scores 67.1 (B) on agent readiness against Tomorrow.io Weather API's 51.4 (D), and leads in every scored category. Both do weather current.

Tomorrow.io Weather APIThe Tomorrow Companies Inc. · HTTP API D51.4/100#578 of 722 Xweather Weather APIVaisala Oyj · HTTP API B67.1/100#219 of 722

Which one, for what

Tomorrow.io Weather API D

Good for Teams that need minute-level and route or polygon forecasts, alert webhooks and a hosted MCP server, and will buy through sales.

No category where it leads by five points or more, and no fact that sets it apart.

Watch for

No public price for paid use. The plan table lists Free and Enterprise, the second by quote

Xweather Weather API B

Good for Teams that need lightning, hail, road weather or tropical data beside ordinary conditions and forecasts, with an MCP server and an OpenAPI file ready for agents.

Ahead on

  • Reliability, 74 against 55
  • Schema & documentation, 83 against 75
  • Agent ergonomics, 78 against 73
  • Security & auth, 52 against 34
  • Payments & pricing, 32 against 20
  • Maintenance & community, 81 against 27
  • Transparency & trust, 68 against 63

Watch for

The REST API documents client_id and client_secret only as query parameters, and the MCP server also accepts the key as ?api_key=

Score by category

CategoryWeight this runTomorrow.io Weather APIXweather Weather APIEdge
Reliability16%205574Xweather Weather API +19
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.27583Xweather Weather API +8
Agent ergonomics13%16.27378Xweather Weather API +5
Security & auth14%17.53452Xweather Weather API +18
Payments & pricing10%12.52032Xweather Weather API +12
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.82781Xweather Weather API +54
Transparency & trust7%8.86368Xweather Weather API +5
Negative events≤1500
Total51.4 · D67.1 · B

Facts side by side

FactTomorrow.io Weather APIXweather Weather API
KindHTTP APIHTTP API
VendorThe Tomorrow Companies Inc.Vaisala Oyj
Hosted endpointhttps://api.tomorrow.io/v4https://data.api.xweather.com
TransportsHTTPHTTP
AuthOAuth or keyOAuth or key
PricingFreemiumFreemium
x402nono
LicenceProprietary service under Tomorrow.io's subscription termsProprietary service under the General Conditions of Subscription Services of Vaisala Group. The OpenAPI files and the agent skills on GitHub are MIT
Tools exposed1119
Read-only variant documentednono
llms.txtyesyes
MCP registrynot listedcom.xweather/weather
Last release2026-07-142026-09-14
Terms last updatedcouldn't be readcouldn't be read
Privacy policy last updatedcouldn't be read2020-06-01
Customer content may train modelscouldn't be readcouldn't be read
Terms restrict automated accesscouldn't be readcouldn't be read
Terms restrict benchmarkingcouldn't be readcouldn't be read
Terms or service can change without noticecouldn't be readcouldn't be read
Arbitration or class-action waivercouldn't be readcouldn't be read
Popularitynone0 stars, 1.4k npm/wk

Verdicts

Tomorrow.io Weather API

A public OpenAPI 3.1 file, Markdown docs with llms.txt and a hosted MCP server with 11 tools suit agents, and a free plan exists. Paid prices are by quote only, free keys are barred from commercial use, the docs give no numeric rate limits, and the status page lists 50 incidents in 85 days, mostly stale or degraded data.

Xweather Weather API

A public OpenAPI file with 236 operations, a hosted MCP server in the official registry and a free tier of 15,000 accesses a month suit agents. REST credentials travel only in the query string, per-minute limits are unpublished, and the group terms bar commercial use of free plans and passing data to third parties unless a service description allows it.

Before you call either

Tomorrow.io Weather API

  1. Send the key in the apikey header, not the query string, so it stays out of URLs and logs
  2. Request only the fields and timesteps needed on POST /timelines. Free plans cover 24 hours back and 5 days ahead at 1h and 1d
  3. Split archive requests. POST /historical takes at most 31 days per call and deducts tokens, 1 for a point and 10 for a polygon
  4. Treat 401 with code 401001 as a missing or bad key. The docs say 403, the live API answered 401 on 8 October 2026
  5. On 429 back off without a hint. Retry-After is documented only for 503
  6. Check the plan's terms before storing or reselling responses. Free accounts are limited to non-commercial use with a Powered by Tomorrow.io link

Xweather Weather API

  1. Check success and error.code on every response. Application errors such as invalid_location return HTTP 200 with success false
  2. Send fields, limit and plimit. The docs put a 15-day hourly forecast at about 600 KB, and about 25 KB with three fields
  3. Read X-Cost-Tokens after each call. Cost is the endpoint multiplier times the intervals requested, so narrow from and to
  4. For MCP, send Authorization: Bearer <client_id>_<client_secret> and avoid the api_key query parameter, which puts the secret in the URL
  5. Add include_tags or include_tools to the MCP URL to load only the tool groups the task needs
  6. On 429 read Retry-After and the X-RateLimit-Reset-* headers. maxhits_min clears at the next minute, maxhits at the period reset

Questions

Which is better for AI agents, Tomorrow.io Weather API or Xweather Weather API?

Xweather Weather API scores 67.1 (B) on agent readiness against Tomorrow.io Weather API's 51.4 (D), and leads in every scored category.

Do Tomorrow.io Weather API and Xweather Weather API need an API key?

Both take an API key or an OAuth sign-in.

Can an agent call Tomorrow.io Weather API and Xweather Weather API without installing anything?

Yes. Tomorrow.io Weather API has a hosted endpoint at https://api.tomorrow.io/v4 and Xweather Weather API at https://data.api.xweather.com.

Other comparisons with Tomorrow.io Weather API or Xweather Weather API

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