The Prediction Markets

What will the peak RONI be for the 2026–27 El Niño?

Closes
Apr 1, 2027, in 5 months
Traded
$252K
Venues
Polymarket, Kalshi
Prices updated
just now
Share

What the markets expect

Over 2.5 68.5%

Next is 2.5°C to 2.9°C at 49%. The venues differ most on Under 1.5 (Polymarket 0.1%, Kalshi 2%), a 1.9-point gap.

Odds by venue

Consensus blends each venue’s last price, weighted by how much has traded there. Best Yes price is the cheapest ask across venues, and the payout is what a winning $100 stake returns before fees. Open a row for each venue’s contract name, bid and ask, and how closely their rules match.

2 of 10 prices are live from the exchange feeds; the rest come from our regular price polls, the oldest 1 min ago. Ages are as of when this page was built.

  • Polymarket
  • Kalshi
Over 2.5
68.5%
Polymarket 68.5%polled, 1 min agoBest Yes 69¢ on Polymarket, $100 pays $145 (1.45x)
Polymarket
Contract
Over 2.5
Last price
68.5%
As of
Polled 1 min ago
Buy Yes
69¢
Sell Yes
68¢
$100 on Yes pays
$145 (1.45x)
Volume
$52K
Trade this on Polymarket
2.5°C to 2.9°C
49%
Kalshi 49%polled, 1 min agoBest Yes 56¢ on Kalshi, $100 pays $179 (1.79x)
Kalshi
Contract
2.5°C to 2.9°C
Last price
49%
As of
Polled 1 min ago
Buy Yes
56¢
Sell Yes
49¢
$100 on Yes pays
$179 (1.79x)
Volume
$44K
Trade this on Kalshi
At least 3.0°C
40%
Kalshi 40%polled, 1 min agoBest Yes 41¢ on Kalshi, $100 pays $244 (2.44x)
Kalshi
Contract
At least 3.0°C
Last price
40%
As of
Polled 1 min ago
Buy Yes
41¢
Sell Yes
40¢
$100 on Yes pays
$244 (2.44x)
Volume
$51K
Trade this on Kalshi
2.25–2.5
30.5%
Polymarket 30.5%polled, 1 min agoBest Yes 31¢ on Polymarket, $100 pays $323 (3.23x)
Polymarket
Contract
2.25–2.5
Last price
30.5%
As of
Polled 1 min ago
Buy Yes
31¢
Sell Yes
30¢
$100 on Yes pays
$323 (3.23x)
Volume
$54K
Trade this on Polymarket
2.0°C to 2.4°C
6%
Kalshi 6%polled, 1 min agoBest Yes 6¢ on Kalshi, $100 pays $1,667 (16.7x)
Kalshi
Contract
2.0°C to 2.4°C
Last price
6%
As of
Polled 1 min ago
Buy Yes
6¢
Sell Yes
4¢
$100 on Yes pays
$1,667 (16.7x)
Volume
$29K
Trade this on Kalshi
1.5°C to 1.9°C
2%
Kalshi 2%polled, 1 min agoBest Yes 2¢ on Kalshi, $100 pays $5,000 (50.0x)
Kalshi
Contract
1.5°C to 1.9°C
Last price
2%
As of
Polled 1 min ago
Buy Yes
2¢
Sell Yes
1¢
$100 on Yes pays
$5,000 (50.0x)
Volume
$6K
Trade this on Kalshi
2.0–2.25
1.5%
Polymarket 1.5%polled, 1 min agoBest Yes 2.2¢ on Polymarket, $100 pays $4,545 (45.5x)
Polymarket
Contract
2.0–2.25
Last price
1.5%
As of
Polled 1 min ago
Buy Yes
2.2¢
Sell Yes
0.7¢
$100 on Yes pays
$4,545 (45.5x)
Volume
$7K
Trade this on Polymarket
Under 1.5Arb
1.4%
Polymarket 0.1%live, just nowKalshi 2%live, just nowBest Yes 0.1¢ on Polymarket, $100 pays $100,000 (1000x)
Polymarket
Contract
Under 1.5
Price
0.1%
As of
Live feed, just now
Buy Yes
0.1¢
Sell Yes
—
$100 on Yes pays
$100,000 (1000x)
Volume
$2K
Trade this on Polymarket
Kalshi
Contract
Below 1.5°C
Price
2%
As of
Live feed, just now
Buy Yes
2¢
Sell Yes
1¢
$100 on Yes pays
$5,000 (50.0x)
Volume
$4K
Trade this on Kalshi
Partial parity

Payoffs match in ordinary outcomes; see the rule differences below the table.

Buying on Polymarket at 0.1¢ and selling on Kalshi at 1¢ nets 90 bps before fees.

1.5–2.0
0.1%
Polymarket 0.1%polled, 1 min agoBest Yes 0.1¢ on Polymarket, $100 pays $100,000 (1000x)
Polymarket
Contract
1.5–2.0
Last price
0.1%
As of
Polled 1 min ago
Buy Yes
0.1¢
Sell Yes
—
$100 on Yes pays
$100,000 (1000x)
Volume
$5K
Trade this on Polymarket

Possible arbitrage before fees: buy Under 1.5 on Polymarket at 0.1¢, sell on Kalshi at 1¢ (90 bps). Check the rules below before trading. See all live spreads

Mostly the same bet: 3 differences

Where they differ

  • Seasons counted differ: Kalshi MJJ 2026 through MAM 2027; Polymarket ASO 2026 through DJF 2026-27.
  • Bracket edges differ above 1.5; only identical ranges ('Below 1.5') are linked.
  • Trading closes at different times: Apr 1, 2027, 3:59 AM UTC on Polymarket and Aug 15, 2027, 2:00 PM UTC on Kalshi.
Polymarket
Polymarket resolves via:
UMA optimistic oracle, source: cpc.ncep.noaa.gov
Kalshi
Kalshi resolves via:
Kalshi (CFTC-regulated exchange), source: NOAA Climate Prediction Center
Show full rule comparison
  • Seasons counted differ: Kalshi MJJ 2026 through MAM 2027; Polymarket ASO 2026 through DJF 2026-27.
  • Bracket edges differ above 1.5; only identical ranges ('Below 1.5') are linked.
  • Trading closes Apr 1, 2027, 3:59 AM UTC on Polymarket and Aug 15, 2027, 2:00 PM UTC on Kalshi.

Summarized from each venue’s published rules; the venue’s own rules page is the final word.

How the odds have moved

The top 3 outcomes on both venues, with the consensus between them. Hover for exact values.

  • Over 2.5
  • 2.5°C to 2.9°C
  • At least 3.0°C

Order books

Each venue’s resting orders for the selected outcome’s Yes contract, side by side. Top of book streams live; depth refreshes every 15 seconds.

Polymarket

Open on Polymarket ↗

Top of book

Connecting
Best bid
—
Spread
—
Best ask
—

Waiting for the first live quote…

Depth · top 8 levels

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Recent trades

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Kalshi

Kalshi doesn’t list Over 2.5 for this event.

What your stake buys

Enter a stake to see where it buys the most after fees, using each venue’s live order book.

$
Buy

Loading both order books…

Buys at the asks resting now (taker orders), cheapest after fees first, from order-book snapshots up to 15 seconds old. Fees: Kalshi 0.07 × price × (1 − price) per share, rounded up to the cent; Polymarket 0.05 × price × (1 − price) per share (other / general rate). Fee calculator. Estimates only, not advice.

About this market

Live prediction market odds for "What will the peak RONI be for the 2026–27 El Niño?". Over 2.5 leads at 68.5%. Next is 2.5°C to 2.9°C at 49%. $252K has traded across 9 outcomes on Kalshi and Polymarket. The market is expected to resolve by Apr 1, 2027.

This market resolves based on the peak RONI — the single highest Relative Oceanic Niño Index (RONI) value reported by NOAA's Climate Prediction Center (CPC) across the overlapping three-month seasons ASO 2026, SON 2026, OND 2026, NDJ 2026-27, and DJF 2026-27, as published in official NOAA CPC RONI updates (https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso/roni/). See each individual market for its bracket and full resolution terms. This market may resolve immediately once NOAA has published a RONI value that determines the peak: the "Over 2.5" outcome resolves "Yes" as soon as any listed season reaches +2.5°C or above. Any other outcome will not be confirmed until NOAA publishes the DJF 2026-27 value, since RONI can still rise in a later season and DJF captures El Niño's typical peak-strength window. The first published RONI value for each listed season is final and governs resolution; no subsequent revision to a season's value will change the outcome once that season's first value has been published. If CPC's RONI dataset is permanently discontinued, other information from NOAA may be used.

Questions

What does the consensus price mean?

It is the price of a Yes contract that pays $1 if the outcome happens. A 14¢ price means traders put the chance near 14%. Where two venues list the same outcome, we blend their last prices, weighting the venue with more trading volume more heavily (neither counts for less than a quarter). When only one outcome can win, each venue’s prices add up to a little over 100% (its margin); the fair chance removes that margin so the outcomes add up to exactly 100%.

How is the payout worked out?

A Yes contract pays $1 if it wins, so at the best ask a $100 stake buys 100 ÷ ask contracts. At 18¢ that is about 555 contracts, paying $556 (5.56x) if Yes happens. Venue fees and price slippage on larger orders are not included.

Why do the venues show different prices?

Each venue has its own traders, fees and order book. Contracts can also settle on slightly different terms, which is why each row lists how closely the rules match.

Is a price gap an arbitrage?

Only when you can buy Yes on one venue below what someone pays for Yes on the other, after fees, and both contracts settle the same way. We show the executable bid and ask so you can check.

How fresh are these prices?

Venue prices refresh every few minutes, and the order book and live quotes stream continuously. Each venue’s card shows when we last observed it.

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