Building a UK Weather Platform with SvelteKit — Developer’s Journey

Repository: https://github.com/lukeoregan88/UK-Weather-Analytics-Dashboard
Live demo: https://lukeoregan88.github.io/UK-Weather-Analytics-Dashboard/

This post documents the end-to-end build of the UK Weather Analytics Dashboard: a performant, SEO-friendly SvelteKit application providing historical and real‑time weather analytics for any UK postcode. It covers architecture, data sources, rate limiting, caching, charts, deployment and lessons learned.

Project overview

The UK Weather Analytics Dashboard provides:

Multi-parameter historical analysis across 10+ years (rainfall, temperature, wind, solar).
Postcode lookup to convert any UK postcode to coordinates.
Interactive Leaflet maps for visual location display.
Real‑time observations and trend analysis.
Mobile-responsive charts and dashboards.

Key goals:

Fast UX with SSR and pre-rendering where appropriate.
Minimal API usage through intelligent caching and rate limiting.
Clear, reusable component architecture with TypeScript safety.
SEO and accessibility first.

Live features

🌧️ Multi-parameter analysis (rainfall, temperature, wind, solar)
📍 Postcode lookup via postcodes.io
🗺️ Interactive mapping (Leaflet)
📊 Time-series visualisations (Chart.js)
⚡ Current conditions and recent observations
🔍 Advanced analytics (drought, heatwave, wind events, solar insights)
📱 Responsive design for mobile and tablet

Technology stack (summary)

Layer	Technology
Framework	SvelteKit + TypeScript
Styling	Tailwind CSS
Charts	Chart.js
Maps	Leaflet (svelte-leafletjs)
Weather API	Open‑Meteo (archive & realtime)
Postcode lookup	postcodes.io
Build	Vite
Hosting	Static hosting / GitHub Pages or CDN

Why SvelteKit + TypeScript

Compiled output with small runtime — excellent for bundle size and performance.
First-class TypeScript support and fast dev server thanks to Vite.
Built-in SSR and good SEO primitives for pre-rendered pages.
Reactive model simplifies complex UI updates (charts, maps, dashboards).

Architecture

The codebase follows a modular structure that separates UI, services and utilities:

src/lib/components — chart and panel components
src/lib/services — API clients, rate limiter, cache service
src/lib/utils — data processing and statistical utilities
src/lib/types.ts — central TypeScript interfaces
src/routes — SvelteKit routes (+layout, +page)

Example folder tree:

src/
├── lib/
│   ├── components/
│   │   ├── RainfallChart.svelte
│   │   ├── TemperatureChart.svelte
│   │   ├── WindChart.svelte
│   │   ├── SolarChart.svelte
│   │   ├── LocationMap.svelte
│   │   └── panels/
│   │       ├── CurrentWeatherPanel.svelte
│   │       └── KeyStatisticsPanel.svelte
│   ├── services/
│   │   ├── weatherApi.ts
│   │   ├── cacheService.ts
│   │   └── rateLimiter.ts
│   ├── utils/
│   │   └── dataProcessing.ts
│   └── types.ts
├── routes/
│   ├── +layout.svelte
│   └── +page.svelte
└── app.html

Core technical implementation

Type-safe data structures

export interface RainfallData {
    date: string;
    rainfall: number; // mm
    temperature?: number; // °C
}

export interface TemperatureData {
    date: string;
    temperature: number; // mean °C
    temperatureMin: number;
    temperatureMax: number;
}

export interface WindData {
    date: string;
    windSpeed: number; // km/h
    windDirection: number; // degrees
    windGusts: number; // km/h
}

export interface SolarData {
    date: string;
    solarRadiation: number; // MJ/m²/day
    uvIndex?: number;
}

Centralised types make data transformations and chart bindings safer and easier to maintain.

Rate limiting (client-side queue)

To prevent exceeding third‑party API limits, the app implements a simple request queue with spacing between requests. This reduces errors and protects quotas.

class RateLimiter {
    private queue: (() => Promise<unknown>)[] = [];
    private active = 0;
    private readonly minutelyLimit = 100;

    async add<T>(fn: () => Promise<T>): Promise<T> {
        return new Promise((resolve, reject) => {
            this.queue.push(async () => {
                try {
                    const r = await fn();
                    resolve(r);
                } catch (e) {
                    reject(e);
                }
            });
            this.processQueue();
        });
    }

    private async processQueue(): Promise<void> {
        while (this.queue.length > 0 && this.active < this.minutelyLimit) {
            const task = this.queue.shift();
            if (!task) break;
            this.active++;
            await task();
            await this.delay(600); // 600ms spacing
            this.active--;
        }
    }

    private delay(ms = 600) {
        return new Promise((res) => setTimeout(res, ms));
    }
}

This conservative limiter spaces calls and prevents bursts that could trigger rate limit errors.

Intelligent caching

Caching reduces repeated archive requests for the same postcode/date range. Cache keys include coordinates and date ranges and support TTLs tuned per endpoint.

export async function getHistoricalRainfall(lat: number, lon: number, start: string, end: string) {
    const key = `rain_${lat}_${lon}_${start}_${end}`;
    const cached = cacheService.get<RainfallData[]>(key);
    if (cached) return cached;

    return rateLimiter.add(async () => {
        const data = await fetchFromOpenMeteoArchive(lat, lon, start, end);
        cacheService.set(key, data, { ttl: 24 * 60 * 60 }); // 24h cache
        return data;
    });
}

Cache strategy:

Short TTL for real-time observations (minutes).
Longer TTL for historical aggregates (hours–days).
Date-range aware cache keys to avoid repeated archive pulls.

Reactive chart components (Chart.js + Svelte)

Chart components use Svelte’s lifecycle and reactivity to create and update Chart.js instances:

<script lang="ts">
    import { onMount } from 'svelte';
    import { Chart, registerables } from 'chart.js';
    import type { RainfallData } from '../types';

    export let data: RainfallData[] = [];
    export let title = 'Rainfall';
    let canvas: HTMLCanvasElement;
    let chart: any = null;

    Chart.register(...registerables);

    onMount(() => {
        createChart();
        return () => chart?.destroy();
    });

    $: if (chart && data) updateChart();

    function createChart() {
        chart = new Chart(canvas.getContext('2d'), {
            type: 'line',
            data: { datasets: [{ label: title, data: data.map(d => ({ x: d.date, y: d.rainfall })) }] },
            options: { responsive: true, scales: { x: { type: 'time' }, y: { beginAtZero: true } } }
        });
    }
</script>

<div class="chart-container"><canvas bind:this={canvas}></canvas></div>

Data sources & integrations

Postcode lookup: postcodes.io — free and reliable UK postcode-to-coordinate conversion.
Weather: Open‑Meteo (archive and realtime) — 10+ year historical archive and current observations.
Optional: Met Office or other licensed datasets for official warnings or enriched data.

Example archive request:

const url = new URL('https://archive-api.open-meteo.com/v1/archive');
url.searchParams.set('latitude', latitude.toString());
url.searchParams.set('longitude', longitude.toString());
url.searchParams.set('start_date', '2014-01-01');
url.searchParams.set('end_date', '2024-12-31');
url.searchParams.set('daily', 'precipitation_sum,temperature_2m_mean,temperature_2m_min,temperature_2m_max,wind_speed_10m_mean,wind_gusts_10m_max,shortwave_radiation_sum');
url.searchParams.set('timezone', 'Europe/London');

Advanced analytics

The dashboard includes event detection and cross-parameter insights:

Drought detection — e.g. 7+ consecutive days with < 1mm rainfall.
Heatwave/cold snap detection based on configurable thresholds.
Extreme event ranking (top wettest / hottest days).
Correlation analysis between temperature, rainfall and solar radiation for agricultural/energy insights.

Example enhanced statistics type:

export interface EnhancedStatistics {
    seasonalRainfall?: Record<string, any>;
    seasonalTemperature?: Record<string, any>;
    topWettestDays: any[];
    topHottestDays: any[];
    rainfallTrend?: { slope: number; pValue?: number };
    temperatureTrend?: { slope: number; pValue?: number };
}

Agricultural and solar features:

Growing degree days, frost risk and recommended planting windows.
Solar energy potential estimates and seasonal generation projections.

Quality, tooling and workflow

Scripts and tools:

{
    "scripts": {
        "dev": "vite",
        "build": "vite build",
        "check": "svelte-kit sync && svelte-check --tsconfig ./tsconfig.json",
        "format": "prettier --write .",
        "lint": "eslint . --ext .ts,.svelte",
        "test:e2e": "playwright test"
    }
}

Code quality:

ESLint + TypeScript rules.
Prettier for consistent formatting.
Playwright for end-to-end tests.
Svelte Check for Svelte-specific type validation.

Build & deployment

Production configuration uses adapter-static for SvelteKit to generate a static build that is CDN-ready:

// svelte.config.js
import adapter from '@sveltejs/adapter-static';

export default {
    kit: {
        adapter: adapter({
            pages: 'build',
            assets: 'build',
            fallback: undefined,
            precompress: false,
            strict: true
        })
    }
};

Production concerns:

Prefer a CDN or static hosting (GitHub Pages, Netlify, Vercel or S3 + CloudFront).
Use edge caching for static assets and a near-user CDN for lower latencies.
Precompress assets where supported and enable cache-control headers.

Performance optimisations

Svelte compilation reduces runtime overhead.
Route-based code splitting with SvelteKit and Vite.
Tree-shaking and removing unused Chart.js adapters where possible.
Lazy load heavier components (maps, charts) and progressively hydrate.
Debounce user inputs (postcode searches) to avoid repeated requests.

SEO & accessibility

SEO practices implemented:

Server-side rendering / static pre-rendering for key pages.
Descriptive meta tags and structured data (WebApplication JSON-LD).
Accessible charts with descriptive alt text and data tables for screen readers.

Example SEO data object:

export const seoData = {
    title: 'UK Weather Analytics Dashboard | Historical Weather Data & Current Conditions',
    description: 'Search any UK postcode for 10+ years of weather history, realtime conditions and advanced analytics for rainfall, temperature, wind and solar.',
    keywords: 'UK weather, historical weather, rainfall analysis, SvelteKit weather, Open-Meteo',
    image: '/og-image.png'
};

Example structured data:

<script type="application/ld+json">
    {
        "@context": "https://schema.org",
        "@type": "WebApplication",
        "name": "UK Weather Analytics Dashboard",
        "description": "Historical and real-time weather analytics for UK locations",
        "applicationCategory": "Weather",
        "isAccessibleForFree": true
    }
</script>

Challenges and solutions

API rate limits — solved with conservative rate limiter and caching.
Large dataset processing — solved with modular data utilities and streaming/aggregate requests.
Mobile performance — solved with responsive charts, reduced initial payload and deferred loading.

Key learnings

Svelte’s reactivity simplifies complex UI flows and reduces boilerplate.
TypeScript prevents many runtime issues and makes refactors safer.
Caching and rate limiting are essential when relying on third‑party archives.
Progressive enhancement and static generation benefit SEO and performance.

Planned improvements

Integrate Met Office warnings for official alerts.
Multi-location comparative analytics.
CSV/JSON exports for researchers.
WebSocket or SSE for live updates.
Service worker for offline support and advanced caching.

Conclusion

Building the UK Weather Analytics Dashboard showcased how modern web tooling (SvelteKit, TypeScript, Vite) and well‑designed API handling can deliver a robust, fast and SEO-friendly weather analytics product. The repo and demo are live — explore the code and dashboard to see the patterns and techniques in practice.

Repository: https://github.com/lukeoregan88/UK-Weather-Analytics-Dashboard
Live demo: https://lukeoregan88.github.io/UK-Weather-Analytics-Dashboard/