Will the UK outright maximum temperature record be broken in 2023?
resolved Oct 1

Last year, on the 19th July 2022, a new UK temperature record of 40.3 °C was set in Coningsby, Lincolnshire; 1.6°C higher than the previous record from 2019. Will this record be broken in 2023?

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bought Ṁ17 of NO

Revisiting the simple calculation earlier, EFI forecast out now to July 20 shows nothing indicating this will resolve YES, so eliminating these days before then from the top 10, we should update from 5/32 to 3/32 ~= 9.4%. I am increasing my NO bet (0.9^29 * 370 mana ~= 17 mana)

bought Ṁ26 of NO

@parhizj Nothing alarming on EFI forecast, increasing NO bet.

~365 mana needed to adjust market to 9.4%. 0.9^27 * 365 ~= 26 mana

bought Ṁ11 of NO

@parhizj Increasing NO bet slightly from looking at 7 day EFI and medium range temp forecasts, considering the market % is still too high for me. Bet size: 180 mana needed to shift to ~9.4%: 0.9^26 * 180 ~= 11 mana

bought Ṁ42 of NO

@parhizj With EFI to July 25 showing nothing exceptional, I'm eliminating 1 more day from the top 10 records: 2/32 ~= 6.3%. I am increasing my NO bet since the market is at 8%.
Bet size: ~580 mana needed to shift to 6.3%: 0.9^25 * 580 ~= 42 mana

bought Ṁ3 of NO

Looking at long range and extended range forecasts it seems that the 6.3% chance is justified, increasing my NO bet:

bought Ṁ38 of NO

@parhizj Nothing alarming in EFI medium-range or extended range forecasts. Increasing NO bet.
~350 mana to shift to 6.3%: (0.9 ^ 21) * 350 ~= 38 mana

bought Ṁ100 of NO

@parhizj With EFI to August 6 showing nothing exceptional, and the extended range EFI showing only a slightly high abnormal temps in late August, I'm eliminating 1 more day from the most recent (1990s+ era) of the top 10 records: 1/32 ~= 3.1%. I am increasing my NO bet since the market is at 7%.
Bet size: ~519 mana needed to shift to 3.1%: 0.9^14 * 2270 ~= 519 mana. This is too much liquidity wise short term so I am capping it at 100.

predicted NO

@parhizj Not going to increase my bets in this market any more given I need the liquidity. Checked the EFI and extended forecasts, it looks very unlikely still.

bought Ṁ200 of NO

Meteorologists forecast 45% chance ("2.3 times the normal figure") that this summer will be "hot". Plus there's an El Nino this year. --> You should bet against me!


predicted NO

@ArunJohnson From your article's headline: "There are no signs yet that last year’s 40C will be breached again, but meteorologists predict such peaks could become the norm"

Whether Britain will again experience a breach of the 40C level remains unclear, however. “There’s no strong indications for it,” said Mark Bevan, a senior Met Office adviser. “On the other hand, we saw it last year, so it’s obviously inherently possible. So never say never.”

Based on that article I wouldn't actually bet YES. the 2.3 times normal figure lacks (quantitative) context with relation to this question.

bought Ṁ18 of NO


Lets consider post 1990 a different era: for the past ~32 years, 5 records were broken. That leaves a probability of about ~16%. It looks like the median for when the records get broken (based on the last 10 record breakers is June 18). From this small sample, it looks like only 1 record was broken before July 11 (10%), so 90% of the records are broken after July 11. Examining forecasts for the next 7 days it seems very unlikely (>99%) a record will be broken, so we will just use the 90% figure in conjunction with 16% (excluding this next week) ~= 14.4%.

I would need to spend 900 mana to bet NO to adjust the market to this probability from 33% to 14%. Given that I am only about 2% confident in updating this prediction correctly every day using more reliable 24H forecasts and (keeping an eye on longer range forecasts) for the next 38 days out (90% confidence in each forecast each day: 0.9^38 ~= 2%), I am reducing this initial bet of NO to 18.

predicted NO

@parhizj TBH I would have bet this down to 15% myself, except I've already got a disproportionate amount in it. Always felt way too high, I'm wondering if my description, and the warming trend, gave people an unrealistic first impression of the probabilities.

predicted NO

@TomFinnie I also vacillate sometimes being unsure how to size my bets given I expect to update several times (and that future bets are going to provide less return since the market will also update)

bought Ṁ5 of NO

@parhizj After 6 days, I am increasing my NO bet. Medium-term forecasts show nothing alarming, nor do EFI reanalysis for 7 days out. Need ~145 mana to decrease market down to my original estimate of 14.4%, limiting the bet size with (0.9^32) * 145 = 5.

predicted NO