Build an Arduino Weather Station with an ASP.NET Core Web API

A practical Arduino-to-ASP.NET Core weather station separates five jobs: sensors measure conditions, firmware packages readings, a Wi-Fi connection sends them, an API validates and accepts them, and a database and dashboard make the results useful. This guide develops a simple temperature-and-humidity prototype using a Wi-Fi-capable board and an ASP.NET Core controller API. It defines a sample payload and server design; it does not claim a particular complete hardware combination has been tested end to end.

Choose the kind of weather station you want to build

Start with the measurements and where the data should go. A temperature-and-humidity station is a manageable first build. Wind, rain, pressure, UV, light, and air quality are separate capabilities that require their own suitable sensors and interfaces.

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1		Weather Meter Kit	$79.95	Buy on Amazon
2		ESP8266 Weather Station Kit for Switching and Displaying Data for Any City in The World	$19.43	Buy on Amazon
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These are documented examples, not a controlled performance comparison. They do not establish relative accuracy, range, battery life, or cost. Arduino describes hyperlocal measurement as a reason to build a station, but does not quantify an accuracy advantage over regional internet weather data.

Select compatible hardware for a temperature-and-humidity prototype

Board and sensor

Arduino’s Modulino Thermo uses an HS3003 temperature-and-humidity sensor. Arduino documents compatibility with UNO R4 WiFi or another Qwiic-capable board, and also describes solderable pins as an alternative connection. Check the exact board’s connector and wiring requirements before assembling the circuit; do not assume every Arduino-compatible board can connect to the module directly. See Arduino’s Modulino Thermo documentation.

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• Kit represents the three core components of weather measurement: wind speed, wind direction and rainfall.
• It uses sealed magnetic reed switches and magnets so you'll need to source a voltage to take any measurements.
• All of the sensors in the weather meter kit are passive components. This means you will need a voltage source in order to measure anything with them.
• Sensors include Wind vane, Cup anemometer, Tipping bucket rain gauge. RJ11 terminated cables.
• Stand: Two-part mounting mast, Rain gauge mounting arm, Wind meter mounting bar, 2x Mounting clamps and 4x Zip ties.

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Expand only for measurements you need

For wind and outdoor placement, Arduino’s outdoor-station example combines a pressure/humidity/temperature sensor with distinct wind-speed and wind-direction sensors. That particular build uses solar power and battery backup; those are design choices, not requirements for every station. Arduino’s UNO Q example lists separate capabilities for pressure, light, UV, rain, and air quality. Each added measurement needs an appropriate component and interface, and outdoor suitability must be checked for the part chosen.

Plan the reading-to-dashboard pipeline

1. Measure: sensors produce values, such as temperature and relative humidity.
2. Sample and package: firmware reads the sensors and creates a message containing values, units, observation time, and device identity.
3. Transmit: a Wi-Fi-capable board sends the message to the server over HTTP. If the sensor board lacks network connectivity, a receiver or other network module can provide the link, but that adds another component and protocol boundary.
4. Validate and accept: the API checks the request and rejects malformed or implausible input before storing it.
5. Persist and display: a database stores observations; a web page or other client requests the current reading or historical series.

This pipeline is a practical design, not a single documented Arduino-to-ASP.NET Core reference build. Arduino examples show differing hardware and data paths, while Microsoft’s documentation covers API construction rather than a specific weather-station device protocol.

Define a clear API contract

A stable contract prevents firmware and server code from making different assumptions. For a prototype, one observation might use this JSON shape:

{
  "deviceId": "garden-station-01",
  "observedAt": "2026-10-04T12:30:00Z",
  "temperatureC": 21.7,
  "relativeHumidityPercent": 48.2
}

The values and timestamp above are illustrative, not measurements. The field names encode units to reduce ambiguity; if you choose different names, document their units just as explicitly. An accepted response can return a server-generated identifier and the time the API recorded the request:

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• The weather station uses the ESP8266-12E to obtain data from the Internet: time of a city, weather data and forecast information for the next 3 days, scrolling on the SSD1306 OLED Display;
• The device can switch to display data from any city in the world - maybe your relatives or friends live there.
• The device uses sensors DHT11, BMP180, BH1750FVI to collect temperature, humidity, Atmosphetic Pressure and light data.
• The weather station reads data indoor via sensor every 5 seconds and uploads it to the Internet every 60 seconds.
• You can see real-time data charts from your phone or computer.Of course you can modify the code to implement different functions.

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{
  "id": "8ef4c",
  "deviceId": "garden-station-01",
  "receivedAt": "2026-10-04T12:30:02Z"
}

For this shape, an endpoint such as POST /api/observations can return 201 Created after persisting an observation, with a location for retrieving it if the application supports that. Return a client error such as 400 Bad Request when required fields are missing or invalid, and avoid storing a partial observation as if it were complete.

• Require a non-empty device identity and a parseable timestamp with an explicit time zone.
• Validate that numeric fields are finite and within application-defined plausible bounds; document those bounds rather than presenting them as universal sensor limits.
• Keep measurement units explicit and consistent from firmware through storage and display.
• Decide whether the server trusts device observation time, records only receipt time, or stores both. For delayed uploads, storing both makes the distinction visible.

Implement the receiver with ASP.NET Core

Microsoft documents two approaches: “ASP.NET Core supports creating web APIs using controllers or using Minimal APIs.” A controller-based API makes request models and endpoint organization explicit, which suits a tutorial with validation and persistence. Minimal APIs are an endpoint-oriented alternative when a compact route is preferable. Neither is universally better for a weather station. See Create web APIs with ASP.NET Core and Tutorial: Create a Minimal API with ASP.NET Core.

A controller can accept a request model, validate it, pass it to a storage service, and return a response. Keep database details outside the controller so validation and storage can be changed independently. Persist at least device identity, observation time, receipt time if needed, and each measurement with its unit understood. A database choice depends on the rest of the application; the cited sources do not prescribe one.

The framework documentation establishes the available API styles, not a device-specific authentication scheme. If the API is reachable beyond a trusted local network, choose an authentication approach appropriate to deployment, transmit over HTTPS where available, and do not place reusable secrets in public firmware examples or a source repository. Restrict each device’s access where practical and provide a way to replace credentials if they are exposed.

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Make transmission resilient and readings interpretable

Connectivity and failure handling are project decisions. A device may be offline when a sample is taken, the server may be unavailable, or a request may time out after the server has already stored it. Choose a sampling interval suitable for the project, queue unsent readings if losing them matters, and retry with a bounded policy. Include a stable observation identifier or another duplicate-detection strategy if retries could submit the same sample more than once. These are engineering choices rather than requirements established by the Arduino examples.

Store device observation time in a consistent time standard such as UTC, and retain server receipt time when diagnosing delays or clock errors. If the board cannot keep accurate time while offline, decide how it obtains time and mark uncertain timestamps rather than silently presenting receipt time as when a measurement occurred.

In the user-facing view, label units and show when the observation was measured or received. A sensor station reports local measurements; it does not automatically provide a forecast. Keep measured conditions distinct from forecast or internet-fed regional weather so viewers do not confuse the two.

Build and verify in manageable stages

1. Confirm the hardware path: check that the board supports the sensor’s interface and that the selected board can connect to Wi-Fi or a network receiver.
2. Read locally first: make firmware display or log sensor values before adding network code. Confirm that the values and units match the sensor documentation.
3. Start the API: create an ASP.NET Core Web API using controllers or Minimal APIs, then implement the observation contract and validation.
4. Test the endpoint independently: send a sample JSON request from a development client and check the success response, validation errors, and stored record.
5. Connect firmware: send the same contract from the device. Inspect server logs and device-side network errors rather than assuming a successful sensor read means successful delivery.
6. Add the view: query stored observations and display labeled current values and history, including timestamps.
7. Test failure paths: try missing fields, malformed JSON, unavailable network, server errors, repeated submissions, and expired or invalid credentials if authentication is configured.

Arduino has also published an ESP32-based weather-monitor example, and a separate weather-station repository in the search results uses PHP, MySQL, and CodeIgniter rather than ASP.NET Core. Those examples illustrate that hardware and backend stacks vary; they are not evidence that a particular ESP32, sensor, or repository is already integrated with the API design here.

Quick Recap

Bestseller No. 1

Weather Meter Kit

$79.95

Bestseller No. 2

ESP8266 Weather Station Kit for Switching and Displaying Data for Any City in The World

$19.43

SaleBestseller No. 3

ELEGOO ESP-32 Super Starter Kit with Tutorial Compatible with Arduino IDE

$31.44

Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.