How Accurate Is a 10-Day Forecast? Depends Who's Counting
July 2, 2026
A 10-day forecast is right only about half the time, per NOAA’s NESDIS: near 90% at five days, about 80% at seven, roughly 50% by day 10. Trust the near term, treat day 10 as a trend.
Key takeaways
- NOAA’s NESDIS puts forecast skill at ~90% (5-day), ~80% (7-day), and only ~50% (10-day) | published figures, not our measurement
- The atmosphere has a hard predictability limit of about two weeks; nobody forecasts specific weather reliably past ~10 days
- Which source you pick matters even one day out: in our 118-day local tracker the best free forecast averaged 92.0 and the paid local incumbent averaged 71.0
- A 10-day forecast is still useful, as a trend, not a plan
- Our tracker is short-range only (midday capture vs next-day verified actuals), so the horizon curve above is NOAA’s, not ours
How accurate is a 10-day forecast, really?
About half the time. NOAA’s NESDIS states that “a 10-day — or longer — forecast is only right about half the time,” while a five-day forecast lands near 90% and a seven-day near 80%. So a 10-day forecast is a coin flip dressed up with an icon and a number: useful for direction, not for scheduling an outdoor wedding.
What is the short answer?
Day 10 is roughly 50/50. That is the load-bearing figure, and it comes from NOAA’s NESDIS, not from us. Our own tracker measures next-day accuracy, not 10-day lead time. Read “50%” as “the direction is probably right, the specifics probably aren’t.” A day-10 high of 74°F might land at 68°F or 80°F, and the rain icon is a hint, not a promise.
What “50% accurate” actually measures
Skill scores measure how often a forecast beats a naive baseline like climatology or persistence, then verify the call against what actually happened. As lead time grows, tiny errors in today’s atmospheric snapshot compound, and the model drifts further from reality with each simulated day. By day 10 the forecast still carries real signal, but the useful part has narrowed from “here’s your afternoon” down to “here’s the rough pattern.”
How does forecast accuracy change by lead time?
It decays with distance, and not gently. NOAA’s published curve runs from ~90% at five days to ~80% at seven days to ~50% at ten. Each extra day of lead time costs accuracy because forecast error grows roughly exponentially, not linearly, so the back half of a 10-day panel is where the confidence quietly drains out.
| Forecast horizon | Rough skill (NOAA/NESDIS) | What to trust it for |
|---|---|---|
| 1–2 days | Very high | Plans: commute, outdoor work, whether you need the sweater |
| 3–5 days | ~90% | Real decisions: travel, events, when to mow |
| 6–7 days | ~80% | Soft planning: Pack for the trend, keep checking |
| 8–10 days | ~50% | Direction only: warmer or colder, wetter or drier |
| 11–14 days | Below 50%, near the limit | Vibes: a hunch, not a forecast |
| 15+ days | Not reliably possible | Nothing specific: See the two-week limit below |
Figures in the table are NOAA/NESDIS published skill estimates. The “what to trust it for” column is our plain-language read of them.
How accurate is a 5-day forecast?
About 90% of the time, per NESDIS. The five-day forecast is the sweet spot where accuracy is high enough to plan around. This is the range where “80% chance of rain Saturday” is worth rearranging your weekend for. Errors exist, but they’re small: a degree or two on temperature, a few hours of timing on precipitation. Trust it, and still glance at it again the day before.
How accurate is the 7-day forecast?
About 80% of the time. The seven-day forecast is worth checking, but treat it as a working draft rather than a signed contract. At a week out the pattern is usually right (a warm stretch, an incoming front) while the daily specifics still wobble. Use it to pack and to pencil in plans, then let the near-term forecast firm up the details as the day approaches.
Why does day 10 fall off a cliff?
Because forecast error compounds. Small uncertainties in today’s measurements amplify with every simulated day, so the gap between day 5 and day 10 is far larger than the gap between day 1 and day 5. That’s the chaos in the system: the reason a 10-day panel looks confident and behaves like a guess. The number on day 10 is a placeholder the model will happily rewrite five more times before it arrives.
Why can’t forecasts see past about two weeks?
Because the atmosphere has a hard predictability limit of roughly two weeks, baked into the physics. As The Washington Post has reported, specific, reliable weather forecasts can’t be made more than about ten days out, and two weeks is the practical ceiling. Past that, tiny errors have grown to swamp the signal entirely: the butterfly effect, but for your weekend.
This is not a technology problem you can spend your way out of. Better satellites and bigger models push skill up within the window, yet the two-week wall stands because it’s a property of a chaotic system, not a limit of computing power. Anyone selling you a confident, specific 30-day forecast is selling you climatology with extra steps.
Which weather forecast is most accurate?
The free ones, at least where we’ve measured. Across 118 days of local tracking in Boone, the best free source (Open-Meteo) averaged 92.0 on our 100-point scale, while the paid local incumbent, Ray’s Weather, averaged 71.0. That’s about a 21-point gap a day, one day out, between two forecasts for the same sky.
One honest caveat up front: This is short-range accuracy. We capture each forecast around midday and score it against the next day’s verified actuals, so it speaks to one-day-out skill, not the 10-day decay curve above. Use it as proof that source choice matters even at close range, because it clearly does.
What our 118-day local tracker found
Free beat paid, consistently. Here’s the window, every source graded the same way on the same days.
| Source | Type | Avg score (118 days) | Days graded Wrong |
|---|---|---|---|
| Open-Meteo | Free | 92.0 | 0 |
| Apple Weather | Free | 88.3 | 1 |
| Ray’s Weather | Paid | 71.0 | 23 |
Open-Meteo’s full record runs 484 days at 91.8 average, so the 118-day number isn’t a lucky streak; it’s the steady state. The grade bands:
- Right is 75+
- Meh is 60–74
- Wrong is under 60
Ray’s landed in Wrong on 23 of 118 days; the two free sources managed one Wrong day between them.
Is free or paid more accurate one day out?
Paid didn’t buy accuracy here. Ray’s Weather has been the High Country’s forecast of record for two decades, and “trusted” turns out not to be the same word as “accurate.” One structural note in fairness: Ray’s never publishes a numeric precipitation amount, so under how we score every forecast on a 100-point scale he forfeits the amount field on wet-forecast days and earns it on dry ones. Even with that accounted for, the free apps most people ignore have been quietly beating the one everybody pays attention to. And the tracker keeping score costs $12 a year to run, so nobody’s accuracy here was bought. Want the deeper cut on that specific question? See is Ray’s Weather actually accurate?
What should you actually trust a 10-day forecast for?
Trends, not plans. A 10-day forecast reliably tells you the shape of the pattern (a warming trend, a wet stretch, a cold front lurking around day 8) and that’s genuinely useful for deciding whether next week leans “sweater” or “shorts.” What it can’t do is promise you a dry Saturday nine days out. Read the far end for direction, then let the near-term forecast fill in the specifics as the day approaches.
Practically, check the 10-day to sense the season’s mood, check the 5-day to make decisions, and check tomorrow to make plans. And when two sources disagree at any range, the tiebreaker isn’t the prettier app. It’s the one with the better track record, which is exactly the thing nobody publishes and we do.
How we score forecasts, and why you can check our math
Every source, every day, on a fixed 100-point scale. High temp is worth 30 points, low temp 30, wind 20, precipitation type 10, and precipitation amount 10, snow-aware, so a blown snow total costs differently than a blown rain total. We capture forecasts around midday, then grade them against the next day’s verified actuals from the Open-Meteo historical archive. The full rubric, including that disclosed archive-as-actuals detail, lives on the methodology page.
Nothing here is a black box. The scores are public, the data exports to CSV and JSON, and you can trace any single day’s grade back to the forecast that earned it.
See today’s index and the live scoreboard
Two places to start. The homepage carries today’s Dave’s Sweater Index and the headline accuracy gap. The Dave’s Sweater Index (DSI) answers the only question that matters most mornings, which is whether it’s sweater weather. For the receipts, the daily scoreboard, every forecaster graded shows all sources scored side by side, updated daily, going back to the start of the record.
Frequently asked questions
Why is the 10-day forecast always wrong?
It isn’t always wrong. It’s right about half the time, per NOAA’s NESDIS, which feels like “always wrong” when you’re checking day 10 for a specific plan. Small errors in today’s data compound over 10 simulated days until only the broad trend survives. Read it as direction, not detail.
How far out can a weather forecast be trusted?
About five to seven days for planning, per NOAA’s published skill figures: roughly 90% accurate at five days and 80% at seven. Beyond that, reliability drops toward a coin flip by day 10, and the atmosphere’s hard predictability limit sits near two weeks.
Is a 5-day or 7-day forecast more reliable than a 10-day?
Yes, substantially. NESDIS puts the five-day forecast near 90% accuracy and the seven-day near 80%, versus roughly 50% at 10 days. Accuracy decays with lead time because forecast error compounds daily, so every day closer to now is a meaningfully better bet than the day beyond it.
Which weather forecast is the most accurate?
In our 118-day Boone tracker, the free sources won: Open-Meteo averaged 92.0 and Apple Weather 88.3, versus 71.0 for the paid local incumbent. That’s short-range, one-day-out accuracy on our 100-point scale. See the daily scoreboard, every forecaster graded for the live numbers.
Are paid weather forecasts more accurate than free ones?
Not in our data. Over 118 scored days the best free source beat the paid local incumbent by about 21 points a day, and the free sources logged one Wrong day between them against the paid source’s 23. Paying for a forecast buys presentation and brand, not necessarily accuracy.
Can any forecast reliably predict weather more than two weeks out?
No, not specific weather. The atmosphere has a predictability limit of roughly two weeks, so “forecasts” past that range are really climatology and long-range trend estimates, not day-by-day predictions. A confident, specific 30-day forecast is a red flag, not a feature.
Does a 10-day forecast still tell you anything useful?
Yes, at the level of trend. A 10-day outlook reliably signals whether a warm, cold, wet, or dry pattern is coming, which is enough to sense next week’s mood: sweater or shorts. Just don’t plan a specific outdoor event around day 10; wait for the 5-day to firm up.
Curious how your favorite forecast actually stacks up? The daily scoreboard, every forecaster graded grades every source against verified actuals, every day, and how we score every forecast on a 100-point scale shows exactly how the points get assigned: public data, checkable math, no black box.