Provisional: the month has only just ended, and NESO can still revise its last few figures.
In October 2026, Britain's electricity averaged 115 gCO₂/kWh, in the low band (70–139 g). That is 6% dirtier than September 2026 (109 g), and 17% cleaner than October 2025 (138 g). Wind made 36.8% of the electricity generated, gas 22.7%, nuclear 14.2% and imports 9.2%; low-carbon sources together made 65.6%. The cleanest half hour was 31 g at 13:00 on Saturday 10 October, and the dirtiest 247 g at 18:00 on Tuesday 6 October. The cleanest day was Friday 9 October (48 g on average); the windiest was Saturday 10 October (62.5% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Thu 1 Oct | 169 | 54.4% | 24.5% | 6.8% | 38.0% | 48 |
| Fri 2 Oct | 124 | 66.8% | 39.3% | 5.5% | 26.8% | 48 |
| Sat 3 Oct | 139 | 57.5% | 24.3% | 7.0% | 28.3% | 48 |
| Sun 4 Oct | 110 | 65.5% | 30.9% | 7.3% | 21.8% | 48 |
| Mon 5 Oct | 115 | 67.5% | 37.9% | 5.3% | 23.2% | 48 |
| Tue 6 Oct | 209 | 39.9% | 8.8% | 4.9% | 45.6% | 48 |
| Wed 7 Oct | 149 | 57.6% | 29.9% | 3.2% | 32.0% | 48 |
| Thu 8 Oct | 66 | 72.1% | 42.2% | 6.6% | 8.6% | 48 |
| Fri 9 Oct | 48 | 82.3% | 62.4% | 3.2% | 8.4% | 48 |
| Sat 10 Oct | 54 | 83.6% | 62.5% | 4.6% | 10.7% | 48 |
| Sun 11 Oct | 123 | 58.8% | 26.4% | 5.9% | 20.9% | 48 |
| Mon 12 Oct | 118 | 66.1% | 41.1% | 1.9% | 24.2% | 48 |
| Tue 13 Oct | 82 | 79.2% | 53.4% | 5.2% | 15.7% | 48 |
| Wed 14 Oct | 101 | 71.6% | 41.3% | 5.0% | 19.3% | 48 |
| Thu 15 Oct | 106 | 68.3% | 41.5% | 3.7% | 20.6% | 48 |
| Fri 16 Oct | 120 | 62.5% | 29.9% | 5.0% | 22.5% | 48 |
| Sat 17 Oct | 65 | 70.4% | 37.7% | 6.2% | 7.4% | 48 |
| Sun 18 Oct | 93 | 66.9% | 33.9% | 5.3% | 14.8% | 48 |
| Mon 19 Oct | 148 | 59.7% | 30.0% | 3.6% | 30.4% | 48 |
| Tue 20 Oct | 122 | 66.5% | 38.8% | 1.7% | 24.4% | 48 |
| Wed 21 Oct | 98 | 68.0% | 39.6% | 2.3% | 17.7% | 48 |
| Thu 22 Oct | 106 | 63.4% | 33.6% | 4.4% | 16.8% | 48 |
| Fri 23 Oct | 82 | 69.4% | 42.1% | 2.1% | 11.9% | 48 |
| Sat 24 Oct | 73 | 77.1% | 55.2% | 1.4% | 12.0% | 48 |
| Sun 25 Oct | 72 | 78.1% | 51.9% | 4.5% | 12.8% | 50 |
| Mon 26 Oct | 81 | 77.0% | 51.3% | 1.1% | 14.2% | 48 |
| Tue 27 Oct | 81 | 78.8% | 51.6% | 3.9% | 16.4% | 48 |
| Wed 28 Oct | 132 | 63.6% | 34.7% | 2.8% | 28.2% | 48 |
| Thu 29 Oct | 209 | 43.9% | 13.7% | 3.4% | 47.8% | 48 |
| Fri 30 Oct | 180 | 51.2% | 20.6% | 4.1% | 40.3% | 48 |
| Sat 31 Oct | 189 | 46.1% | 10.9% | 4.4% | 41.3% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in October 2026, with October 2025 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 171 hours, 23%
- Low (70–139 g): 346 hours, 46%
- Moderate (140–219 g): 204 hours, 27%
- High (220–299 g): 25 hours, 3%
Records in October 2026
- Cleanest half hour
- 31 g 13:00 on Saturday 10 October
- Dirtiest half hour
- 247 g 18:00 on Tuesday 6 October
- Most wind
- 71.1% 22:00 on Friday 9 October
- Most solar
- 25.6% 12:30 on Sunday 4 October
- Most low-carbon
- 89.8% 10:30 on Saturday 10 October
- Least gas
- 3.6% 10:30 on Thursday 8 October
- Cleanest day
- 48 g Friday 9 October
- Dirtiest day
- 209 g Tuesday 6 October
- Windiest day
- 62.5% wind Saturday 10 October
- Sunniest day
- 7.3% solar Sunday 4 October
About these figures
GridMonkey records NESO's carbon intensity and generation mix for Great Britain every half hour: the actual figure where NESO has published one, otherwise its forecast. They are added up by UK calendar day and month. Percentages are shares of the electricity generated, imports included, so the fuels add up to 100%. Low-carbon means wind, solar, nuclear, biomass and hydro. The carbon bands are GridMonkey's: very low under 70 g, low 70–139 g, moderate 140–219 g, high 220–299 g and very high 300 g or more, per kWh. Northern Ireland has its own grid and isn't included.
To see the grid now, open GridMonkey. For the wind farms that ran hardest this week, see the wind farm league table.
Data: NESO Carbon Intensity API (carbonintensity.org.uk), licensed under CC BY 4.0, recorded and summarised by GridMonkey. Figures as of 1 November 2026.