How WeatherTomorrow compares
Our aim is to beat the best forecasts there are. Every forecast on this page, ours and the others, is scored the same way: against what each airport measured.
A year, held out: against the models and the guidance
To see where we stand against current practice, we held back a full year that our model never trained on, 1 November 2025 to 24 October 2026, and scored our published forecast beside:
- the raw global models every weather service starts from;
- the same models corrected for each airport, the simplest local calibration any provider could run;
- in the US, the statistical guidance forecasters use.
Everything is scored at 319 airports on 358 days, all issued 18:00 local, the evening before from what was public by then, against what each airport measured. Our high was off by 0.92° on average. The next best, ECMWF AIFS (AI model), corrected per airport, was off by 1.00°.
| Forecast | High, average error | High within 2° | Low, average error |
|---|---|---|---|
| WeatherTomorrow | 0.92° | 90% | 0.95° |
| ECMWF AIFS (AI model), corrected per airport | 1.00° | 88% | 1.08° |
| ECMWF IFS, corrected per airport | 1.09° | 85% | 1.13° |
| NOAA GFS, corrected per airport | 1.18° | 83% | 1.39° |
| WT-1 alone, our neural network | 1.29° | 79% | 1.10° |
| ECMWF IFS, raw | 1.47° | 73% | 1.35° |
| NOAA GFS, raw | 1.58° | 71% | 1.72° |
| ECMWF AIFS (AI model), raw | 1.68° | 67% | 1.60° |
| Normal for the date | 2.84° | 49% | 2.44° |
| Same as today | 2.98° | 49% | 2.59° |
On US airports, against the official US guidance
In the US, forecasters start from MOS: a physics model corrected against each station's history. On 97 US airports, the same days and the same issue time:
| Forecast | High, average error | High within 2° | Low, average error |
|---|---|---|---|
| WeatherTomorrow | 0.98° | 88% | 0.95° |
| ECMWF AIFS (AI model), corrected per airport | 1.06° | 86% | 1.10° |
| GFS MOS (US guidance), corrected per airport | 1.25° | 81% | 1.17° |
| ECMWF IFS, corrected per airport | 1.26° | 81% | 1.21° |
| NOAA GFS, corrected per airport | 1.33° | 78% | 1.50° |
| GFS MOS (US guidance) | 1.35° | 76% | 1.31° |
| WT-1 alone, our neural network | 1.39° | 76% | 1.15° |
| NAM MOS (US guidance), corrected per airport | 1.42° | 76% | 1.25° |
| ECMWF IFS, raw | 1.53° | 72% | 1.37° |
| NOAA GFS, raw | 1.62° | 70% | 1.81° |
| ECMWF AIFS (AI model), raw | 1.69° | 66% | 1.43° |
| NAM MOS (US guidance) | 1.79° | 64% | 1.31° |
| Normal for the date | 3.80° | 37% | 3.28° |
| Same as today | 3.93° | 40% | 3.37° |
The US National Blend of Models, the official US guidance that blends several corrected models, could be checked from July to October 2026 on 105 US airports. Its next-day high was off by 1.22° (1.02° with its bias removed on the scored days, which favours it), ours by 0.87°.
ECMWF data: CC BY 4.0, www.ecmwf.int. NOAA data: public domain.
Every day, against DWD MOSMIX
MOSMIX is the station forecast of Germany's national weather service (DWD). Every day we score ours and MOSMIX's at the 224 airports where DWD forecasts for a station within 5 km: the same days, the same airport measurements and the same moment of issue. The count for our current forecast, WT-1 combined with ECMWF since 27 October 2026, starts as soon as its first days have been measured.
Before that, from 23 October 2026 to 27 October 2026, our forecast was WT-1 without ECMWF. On 553 airport-days its high was off by 1.31° and MOSMIX's by 0.99°; its low by 1.14° and MOSMIX's by 1.06°.
MOSMIX is the right yardstick because it chases the same goal by other means. It takes DWD's ICON model and ECMWF's IFS, which simulate the whole atmosphere, and corrects them with years of each station's own measurements. We start from ECMWF too, and improve it with WT-1, our neural network trained on GPUs on 26 years of reports from 6,047 airports, calibrated for each airport. MOSMIX never feeds our forecast.
How the comparison with MOSMIX works
- Our forecast is the one issued at 18:00 local time the evening before, as on every airport's track record.
- MOSMIX runs at 03, 09, 15 and 21 UTC and is published about 75 minutes later. We take the latest run that was already published when our forecast was issued, so neither side knows more than the other.
- The truth for both is the day's highest and lowest hourly temperature in the airport's own reports, for the local calendar day. The MOSMIX high and low are the highest and lowest of its hourly temperatures over the same day.
- Only airports with a MOSMIX station within 5 km take part; at most of them the station is the airport itself.
MOSMIX figures: based on data from Deutscher Wetterdienst (opendata.dwd.de), own elements added: we reduce DWD's hourly forecasts to daily highs and lows. Licence: CC BY 4.0.