* The within-day contract fell by 1.25 pence to 27.50 pence per therm by 0912 GMT.
* The February contract was 1.01 pence lower at 27.30 p/therm.
* Traders said a surge in liquefied natural gas (LNG) send-out was weighing on prices.
* Liquefied natural gas (LNG) send-out is nominated at 137 mcm/day, up 60 mcm from Friday.
* High winds last week prevented some tankers from docking at UK terminals but as the wind subsided over the weekend, cargoes have arrived.
* Gas-for-power demand has increased as the wind output has weakened.
* Peak wind generation is forecast at nearly 6.8 gigawatts (GW) on Monday and 6 GW on Tuesday, out of a total metered capacity of around 15 GW, Elexon data showed.
* Analysts at Bernstein said European gas storage remains high at 81% full, above the five-year average, which is also weighing on prices.
* The benchmark Dec-20 EU carbon contract was 0.10 euro higher at 25.54 euros a tonne.
Source: Reuters (Reporting by Nina Chestney)