When Bitcoin stops moving up and altcoins start exploding, that’s not luck. That’s altcoin season. And if you’re still buying altcoins based on hype or a tweet, you’re playing Russian roulette with your portfolio. The real traders? They watch metrics. Not memes. Not influencers. Numbers that have proven, over and over, when the market is about to shift.
As of November 25, 2025, the market is in altcoin season. The Blockchain Center’s Altseason Index is at 78 - meaning 78% of the top 50 altcoins have outperformed Bitcoin over the last 90 days. That’s not a coincidence. It’s a pattern. And it’s been happening since 2017. Every major bull run follows the same rhythm: Bitcoin leads, then altcoins take over. But you don’t guess when it happens. You measure it.
What Exactly Is Altcoin Season?
Altcoin season isn’t just when altcoins go up. It’s when they outperform Bitcoin consistently. The industry standard definition? When 75% or more of the top 50 altcoins by market cap rise faster than Bitcoin over a rolling 90-day window. That’s the threshold. Below 75%? It’s noise. Above 75%? The rotation is real.
This isn’t new. The pattern started showing up after the 2017 ICO boom. Ethereum, Ripple, Litecoin - they all surged when Bitcoin stalled. The same thing happened in 2021. And now in 2025. The market has grown from $17 billion in 2017 to $3.1 trillion today. But the behavior? Still the same. Capital rotates from Bitcoin into altcoins when traders believe the next big gains are elsewhere.
The Four Metrics That Actually Matter
Don’t rely on one number. Real traders cross-check four key signals before moving money.
- Altseason Index (75%+) - The gold standard. If it’s below 75%, you’re not in altseason. Period. As of November 9, 2025, it’s at 78. That’s a clear green light.
- Bitcoin Dominance (Below 50%) - Bitcoin’s share of the total crypto market cap. When it drops under 50%, money is flowing out of Bitcoin and into altcoins. In 2021, it fell from 70.5% to 40.2%. That’s the kind of drop that signals a major shift. Right now, it’s hovering at 48% - close to the danger zone.
- Altcoin-Stablecoin Trading Volume - Look at the volume on pairs like ETH/USDT, SOL/USDC, AVAX/USDT. During altseason, these volumes spike 300-500% compared to Bitcoin-stablecoin pairs. On Binance and Coinbase, that’s not hard to see. If you’re seeing massive volume in Solana or Polygon but Bitcoin trading is flat, that’s confirmation.
- Order Book Depth - This one’s often ignored. When altcoins get real interest, the order books get deeper. In 2023, altcoin order book depth jumped 220% during confirmed altseason. Bitcoin? Only 45%. That means more buyers are willing to pay higher prices without dragging the market down. It’s a sign of institutional interest.
One metric? Could be a glitch. Two? Possible. Three or all four? That’s a signal you act on.
How Altcoins Move - The Sector Rotation Pattern
Altcoin season doesn’t mean every altcoin goes up at once. There’s a sequence. Traders who know this pattern make 2-3x more than those who just buy the top 10.
- Infrastructure & Layer-1 - First up. Ethereum, Solana, Avalanche. These are the engines. They typically surge 350-450% early in the cycle. If you’re waiting for meme coins, you’re already late.
- DeFi Protocols - Next. Uniswap, Aave, Compound. When people start swapping tokens and lending, DeFi follows. Gains: 280-320%.
- Layer-2 Solutions - Optimism, Arbitrum, zkSync. They clean up Ethereum’s fees. Gains: 210-260%.
- AI & Tech Tokens - Fetch.ai, SingularityNET, Akash. These are the next-gen plays. Gains: 180-220%.
- Gaming & Metaverse - Axie Infinity, The Sandbox. Often mid-cycle. Gains: 150-190%.
- Meme Coins - Dogecoin, Shiba Inu, PEPE. Last. Extreme volatility. 400-700% gains, but 80% of them crash within weeks. This is the warning sign the party’s ending.
Watch the order. If meme coins are exploding while Layer-1 tokens are flat? That’s a red flag. You’re in the final stage. Time to start rotating back to Bitcoin or stablecoins.
When Altcoin Season Fails
It’s not always right. In Q1 2022, the Altseason Index hit 76. But TerraUSD collapsed. The entire altcoin market lost 60-75% in 45 days. Why? Because macro forces overrode the signal.
Altcoin season works best after Bitcoin halvings. Historically, it starts 16-18 months later. The last halving was April 2024. The signals started strengthening in August 2025. That timing matches perfectly.
But if there’s major regulation - like the SEC cracking down on unregistered tokens - or a global financial shock? Altcoin season can die overnight. That’s why you never rely on it alone.
How Traders Actually Use These Signals
Here’s what works in practice.
Start watching the Altseason Index and Bitcoin dominance 12-15 months after a Bitcoin halving. That’s your early warning window. When the index hits 65, start putting 10-15% of your portfolio into Layer-1 tokens. At 70, add another 15-20% to DeFi. At 75+, move in 20-25% into late-cycle sectors like gaming or AI.
And here’s the key: always require confirmation. If the Altseason Index hits 75 but Bitcoin dominance is still at 52%? Wait. If volume isn’t rising? Wait. The best traders wait for two or three signals to align. Bitget’s backtesting showed this cuts false signals by 63%.
On Reddit, u/AltcoinGuru2021 made 287% in 112 days by following this exact method in early 2024. But u/CryptoNewbie2023 lost 63% in September 2023 by jumping in on a single 76 reading - no volume check, no dominance check. One had discipline. The other had hope.
The New Tools - And the Risks
TradingView, CoinGecko, and Binance now all have altseason dashboards. TradingView’s widget is used by 42% of professional traders. But here’s the catch: these tools are lagging. They confirm after the move has already started. You won’t catch the bottom. You’ll catch the middle.
Blockchain Center’s Altseason Index just got upgraded in November 2025. Version 4.0 uses machine learning to filter out noise from social hype and fake volume. It’s 31% more accurate. But even that won’t save you from bad timing.
Regulators are watching too. The SEC warned in August 2024 that altseason patterns could be seen as coordinated manipulation - especially if you’re trading unregistered tokens. The IOSCO warned in September 2025 that retail investors are being exposed to disproportionate risk.
And here’s the truth: altcoin season is getting less wild. J.P. Morgan predicts future altseasons will have 40-50% less volatility because institutions are now playing the game. That means fewer 10x coins. But also fewer 90% crashes.
What You Should Do Right Now
Check these three things today:
- What’s the current Altseason Index? (78 as of Nov 9, 2025)
- What’s Bitcoin dominance? (48%)
- Is altcoin-stablecoin volume up 300%+?
If yes to all three? You’re in altseason. But don’t go all-in. Start small. Put 10% into Ethereum or Solana. Watch the next 10 days. If volume keeps rising and Bitcoin stays flat? Add more. If Bitcoin starts climbing again? Exit. Don’t fall in love with an altcoin. Love the pattern.
Altcoin season isn’t a get-rich-quick scheme. It’s a high-probability, high-risk trading window. The metrics tell you when the door is open. It’s up to you to walk through it with your eyes wide open.
What is the Altseason Index and how is it calculated?
The Altseason Index, created by Blockchain Center, measures the percentage of the top 50 altcoins by market cap that have outperformed Bitcoin over a rolling 90-day period. It’s calculated by comparing each altcoin’s price performance against Bitcoin’s during that window. When 75% or more of those altcoins rise faster than Bitcoin, the index crosses into altcoin season territory. As of November 2025, the index reads at 78, confirming active altseason.
Is Bitcoin dominance still a reliable indicator in 2025?
Yes. Bitcoin dominance - the percentage of total crypto market cap held by Bitcoin - remains one of the most reliable signals. Historically, altcoin season begins when Bitcoin dominance drops below 50%. In 2021, it fell from 70.5% to 40.2%. As of November 2025, it’s at 48%, signaling that capital is actively rotating into altcoins. It’s not perfect, but when combined with the Altseason Index and trading volume, it’s a powerful confirmation tool.
Can altcoin season happen without a Bitcoin halving?
Technically, yes - but it’s rare and usually weaker. Since 2017, every major altcoin season has started 16-18 months after a Bitcoin halving. The halving reduces Bitcoin’s new supply, often pushing its price up first. Then, as traders take profits, they rotate into altcoins. Without that catalyst, altcoin season tends to be shorter, less intense, or false. The 2025 altseason followed the April 2024 halving exactly on schedule.
Why do meme coins surge at the end of altcoin season?
Meme coins surge last because they’re the easiest to pump with hype and low liquidity. By the time retail traders jump in, most serious investors have already made their gains from infrastructure, DeFi, and AI tokens. Meme coins attract the last wave of buyers - often FOMO-driven - who don’t understand fundamentals. That’s why they can spike 500-700% in days but crash just as fast. Their rise is a warning sign: the party’s ending.
Are altcoin season signals trustworthy for beginners?
They can be - if you use them correctly. The Altseason Index and Bitcoin dominance are simple to track and widely available. But beginners often make two mistakes: acting on one signal alone, or chasing the biggest gainer. The key is confirmation. Wait for at least two metrics to align - like the index above 75% AND Bitcoin dominance below 50% - before acting. Start with small positions. Learn the sector rotation pattern. Don’t try to catch the top. Just ride the trend.
What’s the biggest mistake traders make during altcoin season?
The biggest mistake is ignoring exit strategy. Many traders see 200% gains and think, ‘This will keep going.’ But altcoin season always ends. The top performers often drop 50-80% in weeks after the peak. The smart traders lock in profits in stages - selling 25% at 100% gain, 25% at 200%, and so on. They don’t wait for the top. They know the metrics will warn them when the rotation back to Bitcoin begins.