When Does Altseason Begin? Early Signs of an Altcoin Season in 2025

Altseason or altcoin season is a short period in which investor capital shifts from Bitcoin (BTC) to altcoins, causing altcoin prices to surge drastically.

This phenomenon is characterized by high volatility, massive price increases, and is often driven by market sentiment and changes in Bitcoin dominance.

In 2025, many investors are asking: “When does altseason start?”. This article will discuss the factors causing the altseason, its history, technical indicators, and predictions for September 2025.

What is Altseason?

Altseason occurs when more than 75% of altcoins outperform Bitcoin in the last 90 days. 

During this phase, BTC's dominance in the total crypto market capitalization declines, while altcoins like Ethereum, Solana, and memecoins surge.

Factors that trigger altseason are usually:

• Bitcoin is moving sideways after a major rally.
• Investors are looking for higher profit opportunities in altcoins.
• Liquidity increases with lower interest rates or economic stimulus.
• There is hype around new innovations (e.g. NFTs, AI tokens, or altcoin-based ETFs).

Read also: Understanding Altseason Index and Altcoin Season: When Will Altseason Occur?

Altseason September 2025: Will It Start?

Recent data shows The Altcoin Season Index is at 41/100, far from the 75 level that would signal an official altseason. 

However, several factors could trigger an altseason in September 2025:

• Macroeconomics:If the Fed lowers interest rates, market liquidity will loosen, increasing interest in risky assets such as altcoins.
• ETFs & Regulation:The potential approval of a Solana ETF or SEI could trigger an influx of institutional capital.
• Historical seasons:September is known to be a relatively good month for altcoins compared to Bitcoin.

If these conditions are realized, the altseason could potentially begin in the late third quarter of 2025.

Altseason History: From 2017 to 2021

If we look back, the first major altseason that was widely noted occurred in late 2017.

At that time, Bitcoin reached a peak price of nearly $20,000, and some of the profits began flowing into altcoins like Ethereum, Ripple, and Litecoin. This movement triggered a surge in altcoin market capitalization within weeks.

A similar phenomenon recurred in 2021, when Bitcoin's price surge to over $60,000 was followed by a surge in capital flows into altcoins like Solana, Cardano, and the memecoin Dogecoin.

This cycle exhibits a consistent pattern: after Bitcoin leads the initial rally, investors typically seek higher-return opportunities in altcoins. Therefore, understanding the history of altseasons helps us predict the likelihood of the next one.

Read Also: 3 Best Altcoins Traders Choose After the Market Crash 

Early Indicators of Altseason

Some early signs of the altseason include:

1. Bitcoin's dominance decline– if BTC drops below 54%, altcoins usually start to strengthen.
2. Altcoin trading volumes rise significantly– reflects new capital flows.
3. Community sentiment & social media– increase in the “altcoin” trend on Google Trends and X (Twitter).
4. Altcoin Season Index– despite its reactive nature, this index remains a popular guide.

Market Indicators and Altcoin Season Index

Many traders ask: what are the signs that altseason is about to start? One popular metric is Altcoin Season Index. 

This index measures the proportion of altcoins that outperform Bitcoin over a given period, usually 90 days. If more than 75% of altcoins outperform Bitcoin, an altseason is in progress.

Technical indicators such as increasing altcoin trading volume, positive social media sentiment, and increased blockchain network activity are also often early signs. However, indicators are only guides.

Macroeconomic conditions, regulations and global market dynamics continue to play an important role in determining direction.

Read also: When Will the 2025 Altcoin Season Happen? Everything You Need to Know

Investor Psychology and Liquidity Dynamics

Altseason isn't just about charts; it's also about investor psychology. 

After seeing massive gains in Bitcoin, many retail traders begin to feel left behind and seek alternatives with lower prices but the potential for significant upside. This is where liquidity shifts.

Community narratives and trends also play a significant role. For example, the NFT trend in 2021 led to a surge in the prices of ecosystem-based altcoins like Ethereum, Solana, and Polygon.

A similar thing also happened in the memecoin category, which despite its weak fundamentals, was still able to quickly attract new investors.

Strategies for Facing Altseason

Know When altseasonIt is indeed difficult, but investors can prepare themselves with a more mature strategy.

• Portfolio diversification: Don't just focus on one altcoin. Spread your risk across L1, DeFi, AI tokens, and memecoins.
• Timing entry & exit: Use technical indicators such as RSI and MACD to determine buy-sell moments.
• Monitor BTC dominance: Sudden changes are often a strong signal of the start of an altseason.
  Be aware of the risks: Altcoins can rise quickly, but they can also fall harder than Bitcoin.

Read also: Altcoin Season vs Bitcoin Season: History and Signs of the Start of Altseason

Conclusion

Altseason is an important phenomenon in the crypto cycle that provides great opportunities for altcoin investors.

Although the Altcoin Season Index is currently low, macroeconomic factors, regulations, and historical patterns point to the potential for an altseason in late 2025. 

Investors need to be astute at reading market signals to capitalize on this momentum.

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FAQ 

What is Altseason?

Altseason is a period where most altcoins outperform Bitcoin in terms of price performance.

When does altseason start?

There is no exact date, but it usually starts after Bitcoin's big rally stops and BTC dominance drops sharply.

What are the altseason indicators?

The main indicators are the Altcoin Season Index, altcoin trading volume, and the decline in Bitcoin dominance.

Is an altseason guaranteed to happen?

No, altseason depends on market conditions, regulations, and investor sentiment.

How long does the altseason last?

Usually only a few weeks to a few months, depending on market trends and cycles.