THE RECEIPTS · SEP 22

The Receipts

Most weather sites tell you they are accurate. This one shows the marks. Every forecast the rock publishes is written down, waited on, and graded against what actually happened. 13,390 graded calls so far, and the numbers below are printed whether they flatter the rock or not.

Graded by the Weather Rock Updated 2026-09-22

A correction, published the way we publish everything. On August 19 we found and fixed a grading bug: the day-ahead scorecard had been matching most predictions against the previous day's weather, not the day each prediction was actually for. Every affected row was regraded in place against its true date, and the originals are preserved. The models scored better than this page used to say, and the numbers on this page are the honest, repaired record.

Was it wet or dry, by how far ahead we called it

1 hour ahead

92percent

905 calls

3 hours ahead

93percent

867 calls

6 hours ahead

92percent

926 calls

12 hours ahead

94percent

909 calls

24 hours ahead

91percent

960 calls

48 hours ahead

84percent

894 calls

Temperature, over the same calls: 1h out by 2.1F, 3h out by 2.1F, 6h out by 2.2F, 12h out by 2.1F, 24h out by 2.1F, 48h out by 2.5F.

Day ahead, model by model

Each model publishes a chance of rain for tomorrow. This is how often a claim above fifty percent matched a day that actually got wet, and how often one below it matched a day that stayed dry. Graded through 2026-09-10.

Model	Right	Days graded
GFS	80 percent	2582
NDFD	79 percent	488
ECMWF	68 percent	2582
NBM	67 percent	2277

Is the confidence honest

Hit rate says whether the rock was right. This says whether it meant it. When the forecast claims a given chance of rain, that share of those hours should actually turn out wet.

The rock said	It actually rained	Hours
0 to 19 percent	1 percent of them	4520
20 to 39 percent	17 percent of them	460
40 to 59 percent	23 percent of them	231
60 to 79 percent	47 percent of them	146
80 to 99 percent	69 percent of them	96

Updated 2026-09-22. Every figure here was graded against what actually happened, from an independent source, never against our own forecast. Nothing on this page is filtered, weighted or rounded in the rock's favour. Where a sample is thin it says so, because a flattering number from twenty readings is not a finding.