AWS Lambda Function - Weather

This single AWS Lambda function detects the URL path and performs one of 2 behaviours.

Built with

Item	Details
Language	C# on .NET 10
Hosting	AWS Lambda (`dotnet10` managed runtime, x86_64, 128 MB) in eu-west-2 (London), called through a Lambda Function URL
Libraries	Amazon.Lambda.Core, Amazon.Lambda.APIGatewayEvents, Amazon.Lambda.Serialization.SystemTextJson, Newtonsoft.Json
Weather data	Open Meteo API (free, no API key)
Tests	NUnit, FluentAssertions, Amazon.Lambda.TestUtilities
Build & deploy	Azure DevOps YAML pipeline: restore, build, test, publish, zip, then upload to AWS Lambda with `aws lambda update-function-code`

Links

Item	Link
AWS Lambda Function hosted at	https://v7jjoujoytcidnjfdihfleknda0pamsr.lambda-url.eu-west-2.on.aws
Git Repo at	https://dev.azure.com/jones-steve/_git/AWS%20Lambda%20Weather
Azure DevOps YAML built at	https://dev.azure.com/jones-steve/AWS%20Lambda%20Weather/_build

Endpoints

Path	Example	What it does
`/html`	https://v7jjoujoytcidnjfdihfleknda0pamsr.lambda-url.eu-west-2.on.aws/html	THIS PAGE. Returns this HTML, describing the function.
`/` (default)	https://v7jjoujoytcidnjfdihfleknda0pamsr.lambda-url.eu-west-2.on.aws	Any other path returns the same page as `/html`.
`/weather`	https://v7jjoujoytcidnjfdihfleknda0pamsr.lambda-url.eu-west-2.on.aws/weather?latitude=53&longitude=-2	Gets the current weather for the given LAT & LNG (lat:53, lng:-2 is Stockport, UK) from the Open Meteo API and returns it as JSON.

Weather request

Item	Details
Query parameters	`latitude` and `longitude` (both required, otherwise returns 400)
Open Meteo API called	https://api.open-meteo.com/v1/forecast?latitude=53&longitude=-2&current=temperature_2m,wind_speed_10m,wind_direction_10m,relative_humidity_2m,rain,is_day
Response type	`application/json`

Weather response fields

Field	Example	Meaning
`Latitude`	53.0	Latitude of the forecast point
`Longitude`	-2.0	Longitude of the forecast point
`Current.Time`	2026-06-14T22:30:00	Time of the reading (GMT)
`Current.Temperature_2m`	12.7	Air temperature 2m above ground, °C
`Current.Wind_speed_10m`	16.2	Wind speed 10m above ground, km/h
`Current.Wind_direction_10m`	78	Wind direction 10m above ground, °
`Current.Relative_humidity_2m`	73	Relative humidity 2m above ground, %
`Current.Rain`	0.0	Rain, mm
`Current.Is_day`	false	Whether it is daytime

Example JSON response

{
    "Latitude": 53.0,
    "Longitude": -2.0,
    "Current": {
        "Time": "2026-06-14T22:30:00",
        "Temperature_2m": 12.7,
        "Wind_speed_10m": 16.2,
        "Wind_direction_10m": 78,
        "Relative_humidity_2m": 73,
        "Rain": 0.0,
        "Is_day": false
    }
}