upslope

September 10, 2026 New England rain event — forecast vs. what fell

event hit rate 91% MAE 0.24″ 32 mountains scored

On September 10, 2026, 31 of 32 scored New England ski resorts recorded measurable rain, peaking at 0.95″ near Killington. upslope’s day-before forecasts verified at a 91% event hit rate with a mean absolute error of 0.24″ across 32 mountains. Ground truth: median of CoCoRaHS volunteer gauges near each resort (min 2 reporting).

Mountain by mountain

Resort Forecast Measured Error Call
KillingtonVT1.04″0.95″+0.09″✓
OkemoVT0.21″0.9″-0.69″✓
PicoVT1.02″0.86″+0.16″✓
RaggedNH0.17″0.84″-0.67″✓
Waterville ValleyNH0.6″0.82″-0.22″✓
LoonNH0.57″0.78″-0.21″✓
Mount SunapeeNH0.14″0.73″-0.59″✓
BromleyVT0.41″0.71″-0.3″✓
BurkeVT0.59″0.71″-0.12″✓
StrattonVT0.33″0.71″-0.38″✓
Jay PeakVT0.82″0.69″+0.13″✓
Magic MountainVT0.15″0.67″-0.52″✓
GunstockNH0.17″0.65″-0.48″✓
Bolton ValleyVT0.7″0.62″+0.08″✓
Smugglers' NotchVT0.7″0.62″+0.08″✓
StoweVT0.87″0.62″+0.25″✓
Mount SnowVT0.38″0.56″-0.18″✓
Bretton WoodsNH0.45″0.54″-0.09″✓
WildcatNH0.43″0.54″-0.11″✓
SugarbushVT0.89″0.51″+0.38″✓
Mad River GlenVT0.93″0.48″+0.45″✓
Sunday RiverME0.25″0.47″-0.22″✓
CannonNH0.56″0.46″+0.1″✓
AttitashNH0.29″0.42″-0.13″✓
CranmoreNH0.2″0.4″-0.2″✓
Pats PeakNH0.09″0.4″-0.31″✗
Black MountainNH0.28″0.32″-0.04″✓
SaddlebackME0.35″0.27″+0.08″✓
SugarloafME0.32″0.27″+0.05″✓
Berkshire EastMA0.11″0.23″-0.12″✓
CrotchedNH0.07″0.14″-0.07″✗
WachusettMA0.17″0.09″+0.08″✗

Forecast = upslope's last published NWS-based rain number the day before. ✓ = correctly called rain above/below 0.1″. Positive error = over-forecast.