Weatherkit

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

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

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.