weatherkit

WeatherKit

Fetch current conditions, hourly and daily forecasts, weather alerts, and historical statistics using WeatherService. Display required Apple Weather attribution. Targets Swift 6.3 / iOS 26+.

Contents

• Setup
• Fetching Current Weather
• Forecasts
• Weather Alerts
• Selective Queries
• Context Queries
• Attribution
• Availability
• Common Mistakes
• Review Checklist
• References

Setup

Project Configuration

1. Enable the WeatherKit capability in Xcode (adds the entitlement)
2. Enable WeatherKit for your App ID in the Apple Developer portal
3. Add NSLocationWhenInUseUsageDescription to Info.plist if using device location
4. WeatherKit requires an active Apple Developer Program membership

Import

import WeatherKit
import CoreLocation

Creating the Service

Use the shared singleton or create an instance. WeatherService conforms to Sendable; keep app cache and UI state isolated separately.

let weatherService = WeatherService.shared
// or
let weatherService = WeatherService()

Fetching Current Weather

Fetch current conditions for a location. Returns a Weather object with all available datasets.

WeatherKit temperatures are Measurement<UnitTemperature> values; display them with .formatted() so units and number formatting follow the user's locale.

func fetchCurrentWeather(for location: CLLocation) async throws -> CurrentWeather {
    let weather = try await weatherService.weather(for: location)
    return weather.currentWeather
}

// Using the result
func displayCurrent(_ current: CurrentWeather) {
    let temp = current.temperature  // Measurement<UnitTemperature>
    let condition = current.condition  // WeatherCondition enum
    let symbol = current.symbolName  // SF Symbol name
    let humidity = current.humidity  // Double (0-1)
    let wind = current.wind  // Wind (speed, direction, gust)
    let uvIndex = current.uvIndex  // UVIndex

    print("\(condition): \(temp.formatted())")
}

Forecasts

Hourly Forecast

Returns 25 contiguous hours starting from the current hour by default.

func fetchHourlyForecast(for location: CLLocation) async throws -> Forecast<HourWeather> {
    let weather = try await weatherService.weather(for: location)
    return weather.hourlyForecast
}

// Iterate hours
for hour in hourlyForecast {
    print("\(hour.date): \(hour.temperature.formatted()), \(hour.condition)")
}

Daily Forecast

Returns 10 contiguous days starting from the current day by default.

func fetchDailyForecast(for location: CLLocation) async throws -> Forecast<DayWeather> {
    let weather = try await weatherService.weather(for: location)
    return weather.dailyForecast
}

// Iterate days
for day in dailyForecast {
    print("\(day.date): \(day.lowTemperature.formatted()) - \(day.highTemperature.formatted())")
    print("  Condition: \(day.condition), Precipitation: \(day.precipitationChance)")
}

Custom Date Range

Request forecasts for specific date ranges using WeatherQuery.

Daily and hourly date-range queries use an inclusive startDate and exclusive endDate. They can include historical data from August 1, 2021. Forecasts are available up to 10 days in the future; each request returns at most 10 daily forecast days or about 240 hourly forecast hours.

func fetchExtendedForecast(for location: CLLocation) async throws -> Forecast<DayWeather> {
    let startDate = Date.now
    let endDate = Calendar.current.date(byAdding: .day, value: 10, to: startDate)!

    let forecast = try await weatherService.weather(
        for: location,
        including: .daily(startDate: startDate, endDate: endDate)
    )
    return forecast
}

For tomorrow-specific guidance, request the local tomorrow day interval rather than using minute forecasts:

func fetchTomorrowForecast(for location: CLLocation) async throws -> Forecast<DayWeather> {
    let calendar = Calendar.current
    let tomorrow = calendar.startOfDay(
        for: calendar.date(byAdding: .day, value: 1, to: .now)!
    )
    let dayAfterTomorrow = calendar.date(byAdding: .day, value: 1, to: tomorrow)!

    return try await weatherService.weather(
        for: location,
        including: .daily(startDate: tomorrow, endDate: dayAfterTomorrow)
    )
}

Weather Alerts

Fetch active weather alerts for a location. Alerts include severity, summary, and affected regions.

func fetchAlerts(for location: CLLocation) async throws -> [WeatherAlert]? {
    let weather = try await weatherService.weather(for: location)
    return weather.weatherAlerts
}

// Process alerts
if let alerts = weatherAlerts {
    for alert in alerts {
        print("Alert: \(alert.summary)")
        print("Severity: \(alert.severity)")
        print("Region: \(alert.region ?? "Unknown region")")
        print("Details: \(alert.detailsURL)") // Non-optional and required for attribution
    }
}

For alert dashboards, name WeatherAvailability explicitly when discussing support checks: it exposes alertAvailability and minuteAvailability only, not a broad availability matrix for current, hourly, or daily weather.

Selective Queries

Fetch only the datasets you need to minimize API usage and response size. Each WeatherQuery type maps to one dataset.

Single Dataset

let current = try await weatherService.weather(
    for: location,
    including: .current
)
// current is CurrentWeather

Multiple Datasets

let (current, hourly, daily) = try await weatherService.weather(
    for: location,
    including: .current, .hourly, .daily
)
// current: CurrentWeather, hourly: Forecast<HourWeather>, daily: Forecast<DayWeather>

Minute Forecast

Available in limited regions. Returns precipitation forecasts at minute granularity for the next hour.

let minuteForecast = try await weatherService.weather(
    for: location,
    including: .minute
)
// minuteForecast: Forecast<MinuteWeather>?  (nil if unavailable)

Available Query Types

Query	Return Type	Description
.current	CurrentWeather	Current observed conditions
.hourly	Forecast<HourWeather>	25 hours from current hour
.daily	Forecast<DayWeather>	10 days from today
.minute	Forecast<MinuteWeather>?	Next-hour precipitation (limited regions)
.alerts	[WeatherAlert]?	Active weather alerts
.availability	WeatherAvailability	Alert and minute forecast availability only
.changes	WeatherChanges?	Significant upcoming weather changes (iOS 18+)
.historicalComparisons	HistoricalComparisons?	Current weather compared to historical averages (iOS 18+)

Dashboard Review Checklist

For a current-temperature and alert dashboard review, explicitly cover:

• Selective .current, .alerts queries instead of weather(for:) for every dataset
• No unconditional onAppear/.task network fetch; use model or cache loadIfNeeded
• WeatherMetadata.expirationDate cache freshness
• WeatherService.shared.attribution, mark URLs, and legalPageURL beside weather data
• Optional alert.region, non-optional alert.detailsURL, and alert detail links
• WeatherAvailability only for alertAvailability and minuteAvailability
• Measurement<UnitTemperature>.formatted() for displayed temperatures
• WeatherKit capability/App ID setup and location permission when using device location

Context Queries

Use the iOS 18+ context queries when the app needs to explain why today's weather matters, not just display raw forecast values. Both query results are optional.

For "unusual tomorrow" or "what is changing?" features, request both .changes and .historicalComparisons. Use .changes for significant upcoming changes, then use .historicalComparisons to explain how current or forecast conditions compare with historical averages.

let (changes, comparisons) = try await weatherService.weather(
    for: location,
    including: .changes, .historicalComparisons
)

For historical statistics, use the WeatherService statistics and summary methods rather than WeatherQuery. In variadic including: calls, state that tuple result order matches the query argument order. Load references/weatherkit-patterns.md when implementing daily summaries, daily statistics, hourly statistics, or monthly statistics. Use statistics properties such as averagePrecipitationProbability, not forecast-only DayWeather.precipitationChance, in statistics examples.

Attribution

Apple requires apps using WeatherKit to display attribution. This is a legal requirement.

Fetching Attribution

func fetchAttribution() async throws -> WeatherAttribution {
    return try await weatherService.attribution
}

Displaying Attribution in SwiftUI

import SwiftUI
import WeatherKit

struct WeatherAttributionView: View {
    let attribution: WeatherAttribution
    @Environment(\.colorScheme) private var colorScheme

    var body: some View {
        VStack {
            // Display the Apple Weather mark
            AsyncImage(url: markURL) { image in
                image
                    .resizable()
                    .scaledToFit()
                    .frame(height: 20)
            } placeholder: {
                EmptyView()
            }

            // Link to the legal attribution page
            Link("Weather data sources", destination: attribution.legalPageURL)
                .font(.caption2)
                .foregroundStyle(.secondary)
        }
    }

    private var markURL: URL {
        colorScheme == .dark
            ? attribution.combinedMarkDarkURL
            : attribution.combinedMarkLightURL
    }
}

Attribution Properties

Property	Use
combinedMarkLightURL	Apple Weather mark for light backgrounds
combinedMarkDarkURL	Apple Weather mark for dark backgrounds
squareMarkURL	Square Apple Weather logo
legalPageURL	URL to the legal attribution web page
legalAttributionText	Text alternative when a web view is not feasible
serviceName	Weather data provider name

Availability

Check whether weather alerts or minute forecast data are available for a location. WeatherAvailability reports only alert and minute availability; other datasets, such as current weather, are expected to be supported for geographic locations.

func checkAvailability(for location: CLLocation) async throws {
    let availability = try await weatherService.weather(
        for: location,
        including: .availability
    )

    // Check specific dataset availability
    if availability.alertAvailability == .available {
        // Safe to fetch alerts
    }

    if availability.minuteAvailability == .available {
        // Minute forecast available for this region
    }
}

Common Mistakes

DON'T: Ship without Apple Weather attribution

Omitting attribution violates the WeatherKit terms of service and risks App Review rejection.

// WRONG: Show weather data without attribution
VStack {
    Text("72F, Sunny")
}

// CORRECT: Always include attribution
VStack {
    Text("72F, Sunny")
    WeatherAttributionView(attribution: attribution)
}

DON'T: Fetch all datasets when you only need current conditions

Each dataset query counts against your API quota. Fetch only what you display.

// WRONG: Fetches everything
let weather = try await weatherService.weather(for: location)
let temp = weather.currentWeather.temperature

// CORRECT: Fetch only current conditions
let current = try await weatherService.weather(
    for: location,
    including: .current
)
let temp = current.temperature

DON'T: Ignore minute forecast unavailability

Minute forecasts return nil in unsupported regions. Force-unwrapping crashes.

// WRONG: Force-unwrap minute forecast
let minutes = try await weatherService.weather(for: location, including: .minute)
for m in minutes! { ... } // Crash in unsupported regions

// CORRECT: Handle nil
if let minutes = try await weatherService.weather(for: location, including: .minute) {
    for m in minutes { ... }
} else {
    // Minute forecast not available for this region
}

DON'T: Forget the WeatherKit entitlement

Without the capability enabled, WeatherService calls throw at runtime.

// WRONG: No WeatherKit capability configured
let weather = try await weatherService.weather(for: location) // Throws

// CORRECT: Enable WeatherKit in Xcode Signing & Capabilities
// and in the Apple Developer portal for your App ID

DON'T: Make repeated requests without caching

WeatherKit models include metadata.expirationDate. Cache responses until that expiration instead of inventing a fixed refresh interval. Avoid unconditional network calls from every onAppear or .task; let an @Observable model, view model, or cache own loadIfNeeded, and reserve explicit refresh for user refresh actions or location/query changes.

// WRONG: Fetch on every view appearance
.task {
    let weather = try? await fetchWeather()
}

// CORRECT: let the model/cache decide whether a fetch is needed
actor WeatherCache {
    private var cached: CurrentWeather?
    private var expiresAt: Date?

    func current(for location: CLLocation) async throws -> CurrentWeather {
        if let cached, let expiresAt, Date.now < expiresAt {
            return cached
        }
        let fresh = try await WeatherService.shared.weather(
            for: location, including: .current
        )
        cached = fresh
        expiresAt = fresh.metadata.expirationDate
        return fresh
    }
}

Review Checklist

• WeatherKit capability enabled in Xcode and Apple Developer portal
• Active Apple Developer Program membership (required for WeatherKit)
• Apple Weather attribution displayed wherever weather data appears
• Attribution mark uses correct color scheme variant (light/dark)
• Legal attribution page linked or legalAttributionText displayed
• Only needed WeatherQuery datasets fetched (not full weather(for:) when unnecessary)
• Minute forecast handled as optional (nil in unsupported regions)
• Weather alerts checked for nil before iteration
• Alert detail links use non-optional detailsURL; optional region is nil-safe
• Responses cached until each model's metadata.expirationDate
• WeatherAvailability used for alert/minute availability, not as a broad support matrix
• Location permission requested before passing CLLocation to service
• Temperature and measurements formatted with Measurement.formatted() for locale

References

• Extended patterns (SwiftUI dashboard, charts integration, historical statistics): references/weatherkit-patterns.md
• WeatherKit framework
• WeatherService
• WeatherAttribution
• WeatherQuery
• WeatherQuery.daily(startDate:endDate:)
• WeatherQuery.hourly(startDate:endDate:)
• CurrentWeather
• CurrentWeather.temperature
• Measurement.formatted()
• Forecast
• HourWeather
• DayWeather
• WeatherAlert
• WeatherAvailability
• WeatherMetadata.expirationDate
• WeatherQuery.changes
• WeatherQuery.historicalComparisons
• WeatherKit updates
• Bring context to today's weather
• Fetching weather forecasts with WeatherKit