What lies behind the simple question “what’s the weather tomorrow?”
Modern weather forecasts are based on digital (numerical) models – large systems of equations that digitally describe atmospheric processes. They periodically calculate temperature, pressure, wind speed and direction, humidity, cloud cover, and other parameters over time and space worldwide.
The main global forecasting systems are: the US NOAA GFS (Global Forecast System), the European ECMWF HRES/ENS (deterministic and ensemble forecast), and Germany’s DWD ICON. Each has its strengths:
ECMWF
The European Centre for Medium-Range Weather Forecasts uses about 9 km horizontal resolution for HRES forecasts up to ~10 days and ensemble (ENS) forecasts up to ~15 days. Due to advanced data assimilation and high computing power, ECMWF is often considered extremely reliable in the medium-range interval. Additionally, some products are published up to 4 times a day. (sources: ecmwf.int).
GFS
GFS is the US government’s global model. The operational horizontal resolution is about 13 km for the first 0–10 days and ~34 km for 10–16 days; the model is run 4 times a day (00/06/12/18 UTC). It has broad coverage and frequent updates, so in some synoptic situations, GFS can be superior. (sources: vlab.noaa.gov).
ICON
DWD Icosahedral Nonhydrostatic model with ~13 km global resolution, running four times a day. Typical forecast length: up to +180 hours for 00/12 UTC runs and up to +120 hours for 06/18 UTC runs. The icosahedral grid helps avoid pole merging issues, and nonhydrostatic physics allows for more accurate representation of finer processes. (sources: dwd.de).
Data assimilation
Real measurements (satellites, weather stations, radars, radiosondes, etc.) are continuously incorporated into the initial state of the models. Advanced assimilation techniques provide an advantage in global forecasts, but certain phenomena are better captured by other or denser regional models at a regional scale. Therefore, there is no single “best” model that works everywhere. (sources: ecmwf.int, dwd.de).
Multi-model synthesis
Many apps combine several models. For example, “Ventusky” allows viewing ECMWF, GFS, ICON, GEM, and others, thus leveraging each model’s strengths (ECMWF reliability, ICON resolution, GFS update frequency) and the advantages of regional models for short-term phenomena. (sources: ventusky.com, Google Play descriptions).
Why do apps differ?
- Different sets of models are used (one or several, + radars, + ML corrections).
- Update frequencies differ (e.g., GFS – 4 times a day; ECMWF products – up to 4 times a day, depending on the set).
- Different grid steps and physics methodologies (hydrostatic vs. nonhydrostatic equations).
- Additional local sources are used (PWS stations, national radars) that refine short-term forecasts.
Popular choices worldwide
AccuWeather
One of the most well-known apps, featuring detailed hourly and daily forecasts, “RealFeel®/RealFeel Shade™”, radar animations, and “MinuteCast®” (predicts the start/end of precipitation with minute accuracy for the next few hours). Offers alerts for hazardous phenomena, widgets, and multi-location tracking. Free with ads and a “Premium” subscription.
The Weather Channel (TWC)
The “IBM Weather Company” app with a user-friendly interface, interactive radars, lightning/hurricane tracking, 15-day forecasts, weather news, and video reports. Powerful alert system and widgets. Free with ads, with a “Premium” plan available.
Weather Underground (WU)
Distinctive for its massive personal weather station (PWS) network (250k+), allowing for hyper-local data. “WunderMap” offers many layers (radar, satellite, wind, UV, AQI, etc.), alerts, and historical reports. Free with ads, subscription available.
Windy.app
Focused on wind and active leisure. Interactive maps with dozens of layers (wind, precipitation, clouds, waves, pressure, UV, AQI, etc.), 10-day forecasts, community features, specialized sports profiles (for sailing, kitesurfing, etc.). Supports multiple model options (ECMWF/ICON/GFS).
Ventusky
Visualization platform/mobile app that combines several models and satellite layers. 14-day detailed forecast with hourly resolution, live radars, and lightning tracking, alerts (e.g., wind gusts, frost), 3D map mode. The app is ad-free.
Others
WeatherBug – many useful maps and lightning tracking; Yr.no – a simple, reliable app/website from the Norwegian Meteorological Institute (widely relies on ECMWF HRES/ENS data outside Norway), free and ad-free.
What works best in our region?
Meteo.lt (Lithuanian HMT)
The official app of the Lithuanian Hydrometeorological Service: Lithuanian interface, thousands of locations, hourly/daily/weekly graphs and tables, radar/satellite/lightning maps, state warnings about hazardous phenomena, widgets. Free.
Foreca
A Finnish meteorological company’s app with Lithuanian localization, minimalist yet informative interface. Focuses on accurate precipitation forecasts, advanced radar tools, alerts, and personalized notifications. Many features – free, with a “Premium” option available.
OrasOnline (Weather & Radar)
International app from “Weather & Radar GmbH” (LT: “OrasOnline Lithuania”). 14-day forecasts, live radar and thunderstorm maps, temperature/cloud cover/wind layers, alerts, weather news. Free with subscription options.
From hourly graphs to lightning networks
- Hourly and longer forecasts. Most apps (AccuWeather, TWC, Ventusky, Windy, Foreca, Meteo.lt, etc.) provide hourly data and 7–15 day overviews; some offer extended periods with lower reliability.
- Radars and maps. TWC, AccuWeather, WU, Ventusky, Windy have interactive radars and satellites; Meteo.lt shows regional radars and alerts; OrasOnline has similar radar functionality.
- Precipitation probability. Shown as % and mm/h; “Ventusky” provides totals and anomalies; “Foreca” and “Meteo.lt” have clear graphs.
- Extreme alerts. TWC/AccuWeather – advanced alarm systems; Meteo.lt – state warnings; WU/Ventusky – third-party and regional sources.
- UV, AQI, wind. UV/AQI provided by TWC, Ventusky, Windy; wind height profiles most comprehensively shown by Windy/Ventusky (useful for sailors, aviators).
- Interface and convenience. TWC/AccuWeather – “for everyone”; Foreca/Meteo.lt – clear and simple; Windy/Ventusky – powerful but require time to get used to.
- Pricing. Most are free with ads + “Premium”. Ventusky, Yr.no, Meteo.lt – ad-free or essentially ad-free; Windy – for PRO add-ons.
Travel, sports, family, agriculture, water, cycling
For travelers
“Ventusky” and “Yr.no” – a good combination of global coverage and simplicity (14-day forecasts, satellites, maps). “AccuWeather” and “TWC” are also suitable for travel – many languages, news, and notifications. For those arriving in Lithuania, it’s worth having “Meteo.lt” for official forecasts.
For athletes and outdoor enthusiasts
For monitoring wind and rapid changes – “Windy” and “Ventusky” (altitude slices, gusts). For runners/cyclists – “Foreca” and “AccuWeather” for detailed hourly forecasts and alerts.
For families and everyday use
“The Weather Channel” or “AccuWeather” – clear, reliable, with alerts and radar. For Lithuania – “Meteo.lt” (in Lithuanian, official alerts). “Foreca” and “OrasOnline” – simple, with widgets.
For farmers and gardeners
The most important – precipitation, frost, wind changes. “Meteo.lt” – official alerts, stations; “Foreca” – accurate precipitation forecasts and radars; “AccuWeather”/”TWC” – additional agricultural indicators (globally), “Windy”/”Ventusky” – wind and front dynamics.
For sailors and water travelers
“Windy” – wind leader; “Ventusky” – wind + waves/currents; “Yr.no” – reliability in the North/Atlantic (ECMWF base).
For cycling and motorcycle enthusiasts
Relevant wind, precipitation, temperature. “Ventusky”/”Windy” – wind visualization; “AccuWeather”/”Foreca” – clear notifications about approaching rain.
How to choose “your” weather app
- Accuracy. Globally, “The Weather Channel” and “AccuWeather” are often well-rated; in Lithuania – “Meteo.lt” (official source) and “Foreca” (especially for precipitation). “Ventusky” stands out with a multi-model combination (e.g., ECMWF + ICON).
- Convenience. “TWC” and “WeatherBug” – easy navigation; “Yr.no” – minimalism; “Foreca”/”Meteo.lt” – clarity; “Windy”/”Ventusky” – a lot of power for advanced users.
- Additional features. Lightning and radars – “Ventusky”, “Windy”, “TWC”, “WeatherBug”. Wind/altitude – “Windy”, “Ventusky”. Maps and webcams – “Ventusky”, “WU”.
- Pricing and localization. Free without ads – “Ventusky”, “Yr.no”, “Meteo.lt”; with “Premium” – “TWC”, “AccuWeather”, “Windy”. In Lithuanian – “Meteo.lt”, “Foreca”, “OrasOnline”.
- Practical tip. Compare at least two sources: check model differences and radar images in real-time – this will reduce surprises.