Think of it like a weather forecast: right more often than not about tomorrow, less sure further out. Every forecast we publish is saved and checked against what happened, so you can judge for yourself.
The actual day landed inside our range on 13 of 14 days. All of these are test forecasts (lighter, dashed): what the model forecast when trained without this season, because we only started saving live forecasts on 13 Oct.
Each dot is one hazy day this season (24 in all). Filled means it was forecast hazy. We compare against the simplest possible guess, that haze levels stay the same as they are now, holding both to the same share of clear days right, so the extra filled dots are what the model adds.
Level typically off by 20 µg/m³ on hazy days (if you assumed levels stayed the same: 31). Mornings (6–11 am): called 85% of hazy mornings, off by 11.
Level typically off by 27 at 1 pm, 24 at 11 pm µg/m³ on hazy days (if you assumed levels stayed the same: 26)
Level typically off by 34 at 1 pm, 29 at 11 pm µg/m³ on hazy days (if you assumed levels stayed the same: 33)
Level typically off by 36 at 1 pm, 34 at 11 pm µg/m³ on hazy days (if you assumed levels stayed the same: 40)
"If haze levels stayed the same" is the simplest guess, made from the readings at that time: by 11 pm it has seen the whole day, which makes it a tougher benchmark than at 1 pm. "Level off" is how far the forecast's middle number was from the worst part of the actual day.
A hazy day is 2 hours or more in NEA's Elevated band (56+) between 06:00 and 22:00. Both kinds of mistake matter: missing a hazy day means playing in haze, and calling a clear day hazy means cancelling for nothing. "If haze levels stayed the same" is the simplest possible forecast, shown so you can see how much the model adds; it calls a day hazy when today already had 2+ hours at Elevated by noon. Every number on this page is from forecasts made without having seen this season. NEA's daily outlook isn't scored here because it forecasts something different: the next day's 24-hour average PSI for the whole island, given as a band; it's shown on the Today page for reference.