Where the weather models disagree in Boston
Boston, Logan station · daily high temperature in °C · the next 14 days · using data from 2026-09-03T12:50 UTC
The models are furthest apart on Mon Sep 14, where 4 of them put Boston's high anywhere from 18° to 34° — ECMWF coldest, AIGFS hottest. That spread is much greater than average for forecasts with a 11-day lead at this location.
The band, day by day
The shaded band is the lowest to the highest model high each day; the line is the median model. The band pales as models drop out with lead — 4 to 7 models across these days — so a narrower far end is fewer opinions, not more agreement.
Every day, every model
highs in °C · typical spread is the median for that lead over the last month here
How this page is built
The models are the independent global centres Open-Meteo serves for this point — GFS, ECMWF IFS, ICON, GEM, UKMO and the AIFS and AIGFS AI models — as The Spread recorded them at its last sweep. NBM and every other blend are left out: a consensus product hides the disagreement this page exists to show.
Each model publishes to a different horizon, which is why Models is counted per day rather than once. Beyond day 14 only two models remain and both are NOAA's, so the page stops there. Range is the lowest to the highest model high; Spread is the difference between those two printed numbers.
Typical spread is the median spread for that lead over the last month of forecasts made here, shown only once ten days of them exist. It is there because a wide band ten days out is ordinary and the same band tomorrow is not — so nothing on this page is called a divergence; the comparison is against what this lead usually looks like at this location.
GEFS p10–p90 is one centre's ensemble, shown beside the band and never as it: it verifies a few degrees warm at every lead.
| Day | Models | Range | Spread | Typical spread | Coldest | Hottest | GEFS p10–p90 |
|---|---|---|---|---|---|---|---|
| Thu Sep 3 | 7 | 25° to 28° | 3° | 2° | AIFS 25° | ECMWF 28° | 26° to 28° |
| Fri Sep 4 | 7 | 26° to 29° | 3° | 3° | GFS 26° | ICON 29° | 28° to 29° |
| Sat Sep 5 | 7 | 20° to 23° | 3° | 2° | GFS 20° | UKMO 23° | 22° to 24° |
| Sun Sep 6 | 7 | 19° to 22° | 3° | 3° | ECMWF 19° | ICON 22° | 19° to 22° |
| Mon Sep 7 | 7 | 23° to 26° | 3° | 4° | UKMO 23° | ICON 26° | 23° to 27° |
| Tue Sep 8 | 7 | 20° to 29° | 9° | 5° | GFS 20° | ICON 29° | 21° to 28° |
| Wed Sep 9 | 6 | 21° to 31° | 10° | 5° | AIFS 21° | ICON 31° | 22° to 31° |
| Thu Sep 10 | 5 | 26° to 33° | 7° | 6° | AIFS 26° | AIGFS 33° | 22° to 32° |
| Fri Sep 11 | 5 | 21° to 24° | 3° | 5° | AIFS 21° | ECMWF 24° | 20° to 30° |
| Sat Sep 12 | 4 | 18° to 24° | 6° | 7° | ECMWF 18° | GFS 24° | 20° to 32° |
| Sun Sep 13 | 4 | 21° to 28° | 7° | 6° | AIFS 21° | AIGFS 28° | 21° to 29° |
| Mon Sep 14 | 4 | 18° to 34° | 16° | 6° | ECMWF 18° | AIGFS 34° | 20° to 31° |
| Tue Sep 15 | 4 | 24° to 33° | 9° | 7° | AIFS 24° | AIGFS 33° | 19° to 31° |
| Wed Sep 16 | 4 | 19° to 26° | 7° | 8° | ECMWF 19° | GFS 26° | 19° to 30° |
Other locations
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