Weatherkit Agent Skill

WeatherKit

Fetch current conditions, hourly and daily forecasts, weather alerts, and

historical statistics using WeatherService. Display required Apple Weather attribution.

Contents

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

Setup

Project Configuration

• Enable the WeatherKit capability in Xcode (adds the entitlement)
• Enable WeatherKit for your App ID in the Apple Developer portal
• Add NSLocationWhenInUseUsageDescription to Info.plist if using device location
• 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+) |

Context Queries

For "unusual tomorrow" or "what is changing?" features on iOS 18+, request the

optional .changes and .historicalComparisons results together: the first

reports significant upcoming changes and the second provides historical context.

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

Historical summaries and statistics use WeatherService methods rather than

WeatherQuery. Load references/weatherkit-patterns.md

for their tuple ordering, APIs, and statistics-specific properties.

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
}

Load references/weatherkit-patterns.md for the complete SwiftUI attribution view and cache integration.

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

Display the appropriate Apple Weather mark and link legalPageURL wherever WeatherKit data appears; use legalAttributionText only when the legal page cannot be shown.

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

Each dataset query counts against your API quota. Use the selective query shown

in Selective Queries and fetch only what the UI displays.

DON'T: Ignore minute forecast unavailability

Minute forecasts are optional in unsupported regions. Check availability and

handle the nil result instead of force-unwrapping it.

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 interval or fetching on every view

appearance. Let a model or cache own loadIfNeeded; the complete actor pattern

is in references/weatherkit-patterns.md.

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