# openmeteo.historical

**stable** **Advanced**

Historical daily weather (ERA5 reanalysis) between two dates.

`GET /v1/openmeteo/historical`

## What you get

One Openmeteo record in Onekey's unified shape, in `data`. If the record does not exist you get a `404 not_found` and are not charged.

## What it costs

- **Advanced · 5 credits** for a fresh fetch, charged only when it succeeds.
- **Free when served from cache (0.2 credit for a cached response over 100 KB).**
- **Free** if the request is invalid (never charged) or the source fails or reports not found (refunded).

## Parameters

| Name | Type | Required | Default | What it is | Constraints |
| --- | --- | --- | --- | --- | --- |
| `lat` | string | yes | (required) | Latitude in decimal degrees (-90..90) | max 10 chars; must match `-?(?:[0-8]?\d(?:\.\d{1,6})?\|90(?:\.0{1,6})?)`; trimmed |
| `lon` | string | yes | (required) | Longitude in decimal degrees (-180..180) | max 11 chars; must match `-?(?:1[0-7]\d(?:\.\d{1,6})?\|\d{1,2}(?:\.\d{1,6})?\|180(?:\.0{1,6})?)`; trimmed |
| `start` | string | yes | (required) | Date YYYY-MM-DD | max 10 chars; must match `\d{4}-\d{2}-\d{2}`; trimmed |
| `end` | string | yes | (required) | Date YYYY-MM-DD | max 10 chars; must match `\d{4}-\d{2}-\d{2}`; trimmed |

## Request

```bash
curl "https://api.onekey.dev/v1/openmeteo/historical?lat=52.52&lon=13.41&start=2024-01-01&end=2024-01-05" \
  -H "x-api-key: YOUR_API_KEY"
```

```python
import requests

res = requests.get(
    "https://api.onekey.dev/v1/openmeteo/historical",
    params={"lat": "52.52", "lon": "13.41", "start": "2024-01-01", "end": "2024-01-05"},
    headers={"x-api-key": "YOUR_API_KEY"},
)
body = res.json()

if body["success"]:
    print(body["data"])
else:
    print(body["error"]["code"], body["error"]["message"])
```

```javascript
const params = new URLSearchParams({ lat: "52.52", lon: "13.41", start: "2024-01-01", end: "2024-01-05" });
const res = await fetch(`https://api.onekey.dev/v1/openmeteo/historical?${params}`, {
  headers: { "x-api-key": "YOUR_API_KEY" },
});
const body = await res.json();

if (body.success) console.log(body.data);
else console.error(body.error.code, body.error.message);
```

## Recorded response

A real Openmeteo response, recorded and returned in Onekey's shape. Fields the platform does not provide are `null`.

```json
{
  "success": true,
  "data": {
    "place": {
      "lat": 52.54833,
      "lon": 13.407822
    },
    "ext": {
      "dates": [
        "2024-01-01",
        "2024-01-02",
        "2024-01-03",
        "2024-01-04",
        "2024-01-05"
      ],
      "temperatureMaxC": [
        7.4,
        7,
        10.6,
        7.3,
        0.9
      ],
      "temperatureMinC": [
        3.4,
        2.5,
        7.3,
        -2.3,
        -0.7
      ],
      "temperatureMeanC": [
        5.3,
        4.4,
        8.7,
        4.1,
        0.3
      ],
      "precipitationSumMm": [
        1.8,
        7.2,
        12.1,
        2.9,
        5.3
      ],
      "windSpeedMaxKmH": [
        19.7,
        20.2,
        27.8,
        33.1,
        21.3
      ]
    }
  },
  "metadata": {
    "platform": "openmeteo",
    "endpoint": "historical",
    "cached": false,
    "stale": false,
    "age_s": 0,
    "fetched_at": "2026-01-01T12:00:00+00:00",
    "credits_charged": 5,
    "request_id": "7f3a9c2e5b1d4c8fa2e6d0b9c4f18e37"
  },
  "error": null
}
```

## Field mapping

How this endpoint's source fields become Onekey's [unified schema](https://onekey.dev/docs/schema.md). Fields the source lacks come back as `null`.

| Source path | Onekey field | Transform |
| --- | --- | --- |
| `latitude` | `place.lat` | `toNumber` |
| `longitude` | `place.lon` | `toNumber` |
| `daily.time` | `ext.dates` | - |
| `daily.temperature_2m_max` | `ext.temperatureMaxC` | - |
| `daily.temperature_2m_min` | `ext.temperatureMinC` | - |
| `daily.temperature_2m_mean` | `ext.temperatureMeanC` | - |
| `daily.precipitation_sum` | `ext.precipitationSumMm` | - |
| `daily.wind_speed_10m_max` | `ext.windSpeedMaxKmH` | - |

## Caching and freshness

- Fresh for about 1 hour. Repeat calls in that window are served from cache and are free.
- Between 1 hour and 1 day the cached copy is still served instantly and marked `stale: true` while Onekey refreshes it in the background.
- If the source is down when a refresh is needed, the last copy can be served for up to 1 day more (marked stale).
- A "not found" is remembered for 5 minutes and is free.
- The cache is shared across all customers, which is what keeps repeat calls cheap.

## What can go wrong

| Status | Code | What to do |
| --- | --- | --- |
| 401 | `unauthorized` | Check the `x-api-key` header. |
| 402 | `insufficient_credits` | [Add credits](https://onekey.dev/pricing); your balance must cover the price. |
| 404 | `not_found` | That record does not exist. Free; do not retry. |
| 422 | `invalid_params` | Fix the parameters using the table above. Free. |
| 429 | `rate_limited` | Wait `Retry-After` seconds, then retry. |
| 502 | `upstream_error` | The source failed. Refunded; retry with backoff. |

See [Errors](https://onekey.dev/docs/errors.md) for the full list and retry guidance.

Status: stable (verified against the live source).