Quick answer: No. As of October 9, 2026 it is not alt season by the standard test, which needs 75% of the top altcoins to beat Bitcoin over 90 days. Blockchaincenter's Altcoin Season Index read 47 and CoinMarketCap's read 58. Bitcoin dominance was 59.2% (CoinGecko), up about a point over 90 days on CoinMarketCap's data. Since April 2017 that index has been in alt season on only 12% of days, and on none so far in 2026.
Every cycle, the same question comes back around: is alt season coming? In 2026, traders are once again glued to Bitcoin dominance charts, waiting for the moment capital starts leaking out of BTC and into everything else. Here's the honest version nobody's thumbnail will tell you: an alt season can't be predicted, but it can be measured, and measuring beats prophesying every single time. So we measured it, across nine and a half years of daily data.
What an alt season actually is
"Alt season" is trader shorthand for a stretch of time when altcoins (broadly, everything that isn't Bitcoin) outperform Bitcoin itself. Not one lucky coin doing a moonshot. A wide, sustained tilt where the majority of the market is running hotter than BTC.
That distinction matters. A single alt pumping while everything else bleeds isn't an alt season; it's a lottery ticket that happened to get scratched. The real phenomenon is breadth: large caps, mid caps, and eventually the long tail all outpacing Bitcoin at the same time.
The most widely used formal rule is the Altcoin Season Index: take a basket of the largest coins, excluding stablecoins and wrapped or asset-backed tokens, and count what share of them beat Bitcoin's price change over the last 90 days. The two best-known versions use the same thresholds but different baskets, so they rarely print the same number:
| Index | Basket | Window | Alt season | Bitcoin season | Reading on Oct 9, 2026 |
|---|---|---|---|---|---|
| Blockchaincenter Altcoin Season Index | Top 50 coins | 90 days | 75 or higher | 25 or lower | 47 |
| CoinMarketCap Altcoin Season Index | Top 100 coins | 90 days | 75 or higher | 25 or lower | 58 |
| WenMoonLambo breadth reading | 34 liquid Binance alts | 90 days | 75 or higher | 25 or lower | 68 |
Same market, same day, three answers from 47 to 68, and all three say "not alt season." The spirit is always the same, though: alt season is a market-wide condition, not a coin-specific event.
The classic rotation story
There's a folk pattern traders have been retelling since at least 2017, and it goes like this. Bitcoin runs first. Early profits get recycled into the big, liquid alts. As confidence (and greed) builds, capital wanders further out the risk curve into mid caps, then small caps, then things with dog mascots. Eventually the music slows, everything rotates back into BTC or stablecoins, and the long tail is left holding the bag.
The alt seasons of 2017β18 and 2021 roughly fit that shape, which is why the story survives. Bitcoin's share of the crypto market fell from 87.6% at the start of 2017 to 32.4% on January 14, 2018, and from 71.8% on January 3, 2021 to 39.3% on May 19, 2021.
But be clear-eyed about what the story is: a pattern people noticed after the fact, not a law of nature. Markets are under no obligation to repeat it, on schedule or at all. Structural things change between cycles (new assets, new kinds of market participants, ETFs, different liquidity conditions) and any of those can bend or break the old script.
Treat the rotation story as a map of what has happened, not a timetable of what will.
Bitcoin dominance: the alt season metric everyone watches
Bitcoin dominance is BTC's market cap as a share of the entire crypto market. When dominance falls while total market cap holds or rises, money is, by definition, flowing relatively toward alts. That's why it's the first chart anyone opens in an alt season debate.
| Date | BTC dominance (CoinMarketCap) | Altcoin Season Index that day (Blockchaincenter) |
|---|---|---|
| Jan 2, 2017 | 87.6% (2017 high) | not published yet |
| Jan 14, 2018 | 32.4% (lowest in CMC's daily record since 2013) | 98 |
| Sep 6, 2019 | 70.9% (2019 high) | 7 |
| Jan 3, 2021 | 71.8% (2021 high) | 18 |
| May 19, 2021 | 39.3% (2021 low) | 84 |
| Sep 9, 2022 | 37.7% (2022 low, in a bear market) | 96 |
| Jun 27, 2025 | 65.1% (highest since January 2021) | 18 |
| Oct 9, 2026 | 59.5% (12-month range: 57.3% to 60.6%) | 47 |
It's a genuinely useful gauge. It's also a distorted one, and the distortions are worth knowing before you bet your thesis on it:
- Stablecoins live in the denominator. On October 9, 2026, CoinGecko put BTC at 59.2% of the market, with Tether at 6.6% and USDC at 2.6%. Leave just those two stablecoins out and Bitcoin's share of the rest is about 65%. A wave of new stablecoin supply pushes Bitcoin dominance down without a single person buying an altcoin. Falling dominance can mean "risk appetite for alts" or "people parked cash on the sidelines": very different stories, same chart.
- New listings inflate the alt side. Thousands of tokens launch every cycle, and each one adds market cap to the non-BTC bucket the day it lists.
- It says nothing about breadth. Dominance can slip because a couple of mega-cap alts rallied while five hundred others went nowhere.
So dominance is a headline, not the whole article. Use it, just don't use it alone.
How often is it actually alt season? We checked 3,459 days
We took every daily reading of Blockchaincenter's 90-day Altcoin Season Index from April 3, 2017 to October 9, 2026, and lined it up with CoinMarketCap's daily Bitcoin dominance and Binance's daily Bitcoin and ETH/BTC closes. Then we asked how often the alt season condition has actually been met, how long it lasted, and what came with it.
| Year | Days at 75+ (alt season) | Days at 25 or lower (Bitcoin season) |
|---|---|---|
| 2017 (from April 3) | 120 (45%) | 93 (35%) |
| 2018 | 75 (21%) | 138 (38%) |
| 2019 | 17 (5%) | 162 (44%) |
| 2020 | 42 (12%) | 71 (20%) |
| 2021 | 89 (24%) | 35 (10%) |
| 2022 | 40 (11%) | 95 (26%) |
| 2023 | 0 | 169 (46%) |
| 2024 | 21 (6%) | 79 (22%) |
| 2025 | 12 (3%) | 111 (31%) |
| 2026 (to Oct 9) | 0 | 3 (1%) |
| All days | 416 of 3,459 (12.0%) | 956 (27.6%) |
Alt season is the rarest of the three states. The market spends most of its time, 60% of days, in the unremarkable middle. And 2026 has been the most stuck-in-the-middle year in the data: 279 of 282 days between 26 and 74, a high of 67 on August 2 and a low of 22 on May 15.
The episodes themselves are short and getting shorter. Merging alt season days separated by less than two weeks gives 16 episodes since 2017. The ones that lasted a week or more:
| Episode | Days at 75+ | Peak reading | BTC dominance, 90 days before β first day | BTC 90-day change at start |
|---|---|---|---|---|
| AprβAug 2017 (already under way when the data starts) | 120 | 100 (Jul 16) | 87.6% β 64.7% | no data |
| JanβMar 2018 | 75 | 100 (Feb 18) | 49.2% β 38.6% | +210% |
| Dec 2019 | 11 | 85 (Dec 4) | 70.1% β 66.4% | β31% |
| Feb 2020 | 7 | 77 (Feb 15) | 66.0% β 63.2% | +19% |
| AugβSep 2020 | 33 | 89 (Aug 17) | 67.1% β 60.6% | +36% |
| MarβJun 2021 | 89 | 98 (May 18) | 67.0% β 59.8% | +134% |
| AugβSep 2022 | 37 | 98 (Aug 10) | 41.7% β 40.5% | β20% |
| Jan 2024 | 13 | 84 (Jan 22) | 50.0% β 49.7% | +46% |
| Dec 2024 | 7 | 88 (Dec 4) | 56.3% β 55.5% | +67% |
| Sep 2025 | 12 | 80 (Sep 19) | 63.4% β 57.6% | +9% |
What the data says:
- Alt seasons are measured in weeks, not years. The longest unbroken runs at 75 or above were 88 days (March 25 to June 20, 2021) and 71 days (January 6 to March 17, 2018). Since the 2022 episode ended on September 14, 2022, the index has spent just 33 days at 75 or above in four years, and never more than 11 days in a row (September 11β21, 2025). The last alt season day was September 26, 2025.
- Falling dominance came with every alt season, but most dominance drops weren't one. On all 412 alt season days with dominance data, Bitcoin dominance was lower than 90 days earlier. Turn it around, though, and a falling dominance chart is a weak signal unless the drop is large:
| BTC dominance compared with 90 days earlier | Days | Share that were alt season (2017β2026) | Same, since 2019 only |
|---|---|---|---|
| Lower by any amount | 1,558 | 26% | 17% |
| Lower by more than 3 points | 711 | 55% | 41% |
| Lower by more than 5 points | 482 | 72% | 58% |
| Lower by more than 8 points | 336 | 89% | 80% |
On October 9, 2026, dominance was about one point higher than 90 days earlier (59.5% vs 58.5%).
- ETH/BTC rising is close to a requirement, not a trigger. Since late 2017, ETH/BTC was higher than 90 days earlier on 96% of alt season days (283 of 296). But of all the days ETH/BTC was up over 90 days, only 21% were alt season. On October 8, 2026, ETH/BTC closed at 0.0303: up 8.1% over 90 days, down 17.5% over a year, and 66% below its December 2021 high of 0.0879. Its cycle low was 0.01805 on April 21, 2025, the lowest close since January 2020.
- Some "alt seasons" happen in bear markets. In 35% of alt season days since late 2017 (105 of 296), Bitcoin was lower than 90 days earlier. The August 2022 episode began with BTC down 20% over 90 days. The index only asks whether alts beat Bitcoin, so alts falling less than Bitcoin counts. Check the direction of the whole market before reading a high number as a party.
The fine print: Blockchaincenter's history has 14 small gaps, CoinMarketCap's dominance history has five days recorded as zero, which we dropped, and the 2017 episode was already running when the series begins.
Different baskets give different answers, too. Over the 2.5 years where all three exist, the indexes broadly agree (daily correlations of 0.81 to 0.90), but in 2026 so far our reconstruction of the 34-coin Binance reading spent 153 days at 25 or lower, against 3 for Blockchaincenter and 13 for CoinMarketCap. CoinMarketCap's top 100 currently includes gold-backed tokens (XAUt, PAXG) and exchange tokens (LEO, OKB), which don't behave like typical altcoins. It's a description of the past, not a rule.
Signs a rotation is (or isn't) actually happening
If you want a more honest read than one ratio, look for confluence across several angles:
- Breadth. Are most large alts outperforming BTC, or just a few outliers? Rotation is a crowd behavior. No crowd, no rotation. This is exactly what the Altcoin Season Index counts.
- Large-cap ratios first. Traders have historically watched whether the biggest alts firm up against Bitcoin before the smaller stuff moves. In the data above, ETH/BTC was up on 96% of alt season days. If large caps can't outperform BTC, the risk-curve story hasn't even started.
- The size of the dominance drop. A one-point dip is noise. Drops of more than 8 points over 90 days lined up with alt season 89% of the time.
- Where the stablecoins go. Stablecoin supply sitting idle is dry powder; stablecoin supply being spent into alt pairs is rotation in progress.
- Sentiment and attention. Alt seasons come with a mood. When social feeds and search interest shift from Bitcoin toward alt narratives, that's a noisy but real tell. You can watch the mood layer on our Sentiment Intelligence page and the market-wide reading on today's Fear & Greed page.
The anti-signals matter just as much. If BTC is selling off hard, alts usually fall harder. That's not rotation, that's a drawdown. If dominance is drifting down purely on stablecoin growth, that's not rotation either. A rotation you can only see in one cherry-picked chart probably isn't one.
One score instead of twelve open tabs
This is exactly why we built the Alt Season Score: a 0β100 composite of seven real-data inputs, each scored 0β100 and weighted:
| Input | Weight | What it measures |
|---|---|---|
| BTC dominance momentum | 25% | An equal-weight basket of 34 liquid Binance alts vs Bitcoin over 30 days |
| ETH/BTC trend | 20% | 30-day change, plus whether ETH/BTC is above its 50-day average |
| TOTAL2 trend | 15% | 30-day change of that alt basket, including ETH |
| TOTAL3 trend | 15% | 30-day change of the basket without ETH |
| Stablecoin dominance | 10% | Share of the market held by six major stablecoins (lower reads as alt-friendly) |
| Altcoin breadth | 10% | Share of the 34 alts trading above their 50-day average |
| Funding rates | 5% | Average Binance perpetual funding across six majors |
Readings of 25 or below are labeled Bitcoin Season, 26β50 Transition, 51β75 Early Alt Season and above 75 Full Alt Season. At 21:39 UTC on October 9, 2026 it read 73.6, Early Alt Season, carried by alts beating Bitcoin by 16 points over the previous 30 days while the ETH/BTC trend and stablecoin inputs stayed weak.
Because the score is built on 30-day changes, it reacts faster than the 90-day indexes above and can sit in its alt season bands while they don't. That's a feature if you want to see momentum early, and a reason to check breadth before you believe it. It doesn't forecast anything, and it doesn't pretend to. The full breakdown, with the 90-day breadth reading, relative-strength ladder and sector rotation, lives in the Alt Season workspace.
If you want to practice trading around regime shifts without paying real tuition, try the $10,000 paper-trading demo: it's free with no signup and runs on real Binance market data, enough rope to test a rotation thesis and find out what you'd actually do when dominance rolls over. And if terms like "relative strength" are new to you, the free TA course covers the foundations at your own pace.
Frequently asked questions
Is it alt season right now? Not as of October 9, 2026. Blockchaincenter's Altcoin Season Index read 47 and CoinMarketCap's read 58, against a threshold of 75. The last day Blockchaincenter's index was at 75 or above was September 26, 2025.
What is the Altcoin Season Index? It's the share of the largest coins (top 50 for Blockchaincenter, top 100 for CoinMarketCap, excluding stablecoins and wrapped tokens) that beat Bitcoin's price change over the last 90 days. 75 or higher is alt season; 25 or lower is Bitcoin season.
How long does alt season last? Usually weeks. The longest unbroken stretches since 2017 were 88 days in 2021 and 71 days in early 2018, and since September 2022 no stretch has lasted longer than 11 days.
What Bitcoin dominance level means alt season? There's no fixed level; the drop matters more than the number. Alt seasons have started with dominance as high as 66% (December 2019) and as low as 39% (January 2018), but on every alt season day dominance was lower than 90 days earlier, and drops of more than 8 points lined up with alt season 89% of the time.
Was there an alt season in 2025? Only briefly. Blockchaincenter's index was at 75 or above on 12 days between September 11 and 26, 2025, peaking at 80 on September 19, and it hasn't returned there since.
Does ETH/BTC have to rise for alt season? Almost always. Since late 2017, ETH/BTC was up over 90 days on 96% of alt season days, but only 21% of the days ETH/BTC was up turned out to be alt season, so a rising ETH/BTC on its own isn't enough.
The bottom line
Nobody knows whether 2026 delivers an alt season, and anyone claiming certainty is selling something. What nine and a half years of data do say: alt season is rare (12% of days), short (weeks, and shorter every cycle since 2022), always comes with falling Bitcoin dominance and a rising ETH/BTC, and is not guaranteed by either.
Watch the tape honestly: dominance with its flaws in mind, breadth over anecdotes, stablecoin flows over vibes. Or let the Alt Season Score do the aggregation for you. The job is measuring, not prophesying. Measure well, and if the rotation comes, you won't need anyone's prediction to see it.
Data: Blockchaincenter 90-day Altcoin Season Index daily values, April 3, 2017 β October 9, 2026 (3,459 days); CoinMarketCap Altcoin Season Index, March 22, 2024 β October 9, 2026; CoinMarketCap daily Bitcoin dominance, April 2013 β October 9, 2026; Bitcoin (BTC/USDT) and ETH/BTC daily closes from Binance, August 2017 β October 8, 2026; market shares from CoinGecko on October 9, 2026. Alt season episodes merge 75+ days separated by less than two weeks.
Nothing here is financial advice. WenMoonLambo is a paper-trading platform β all trading happens with play money on real market data.