In June 2026, Britain's electricity averaged 132 gCO₂/kWh, in the low band (70–139 g). That is 8% dirtier than May 2026 (122 g), and 33% dirtier than June 2025 (99 g). Wind made 27.9% of the electricity generated, gas 26.8%, imports 14.6% and solar 11.2%; low-carbon sources together made 56.1%. The cleanest half hour was 38 g at 12:30 on Saturday 13 June, and the dirtiest 256 g at 03:30 on Tuesday 30 June. The cleanest day was Saturday 13 June (58 g on average); the windiest was Thursday 4 June (52.3% wind).
Carbon intensity, day by day
Day by day, as a table
| Day | gCO₂/kWh | Low-carbon | Wind | Solar | Gas | Half hours |
|---|---|---|---|---|---|---|
| Mon 1 Jun | 156 | 48.8% | 24.3% | 7.8% | 32.6% | 48 |
| Tue 2 Jun | 170 | 46.1% | 19.2% | 9.7% | 35.0% | 48 |
| Wed 3 Jun | 82 | 68.4% | 44.3% | 7.4% | 12.1% | 48 |
| Thu 4 Jun | 66 | 73.0% | 52.3% | 9.1% | 9.7% | 48 |
| Fri 5 Jun | 102 | 63.5% | 35.1% | 10.6% | 18.7% | 48 |
| Sat 6 Jun | 88 | 64.9% | 40.5% | 7.0% | 14.3% | 48 |
| Sun 7 Jun | 81 | 71.9% | 47.6% | 9.9% | 14.1% | 48 |
| Mon 8 Jun | 133 | 55.5% | 28.4% | 9.6% | 27.0% | 48 |
| Tue 9 Jun | 92 | 64.4% | 32.5% | 12.2% | 14.2% | 48 |
| Wed 10 Jun | 145 | 52.6% | 22.2% | 10.2% | 29.0% | 48 |
| Thu 11 Jun | 125 | 59.0% | 34.5% | 5.4% | 24.4% | 48 |
| Fri 12 Jun | 72 | 73.9% | 50.5% | 9.9% | 12.8% | 48 |
| Sat 13 Jun | 58 | 78.6% | 50.7% | 14.1% | 10.1% | 48 |
| Sun 14 Jun | 99 | 58.7% | 25.1% | 16.0% | 15.6% | 48 |
| Mon 15 Jun | 151 | 47.0% | 15.2% | 12.8% | 28.8% | 48 |
| Tue 16 Jun | 173 | 45.2% | 18.0% | 10.1% | 37.0% | 48 |
| Wed 17 Jun | 130 | 56.3% | 30.1% | 8.7% | 26.7% | 48 |
| Thu 18 Jun | 151 | 51.4% | 24.0% | 10.5% | 31.7% | 48 |
| Fri 19 Jun | 120 | 57.7% | 30.2% | 12.3% | 24.4% | 48 |
| Sat 20 Jun | 150 | 46.8% | 16.7% | 11.8% | 29.8% | 48 |
| Sun 21 Jun | 152 | 46.2% | 10.6% | 15.4% | 30.8% | 48 |
| Mon 22 Jun | 154 | 51.3% | 19.8% | 13.7% | 32.9% | 48 |
| Tue 23 Jun | 180 | 47.5% | 15.6% | 13.9% | 39.7% | 48 |
| Wed 24 Jun | 192 | 42.1% | 10.6% | 14.1% | 42.2% | 48 |
| Thu 25 Jun | 166 | 51.0% | 19.6% | 14.3% | 37.0% | 48 |
| Fri 26 Jun | 170 | 51.6% | 21.2% | 13.5% | 37.8% | 48 |
| Sat 27 Jun | 140 | 56.6% | 27.4% | 13.5% | 30.0% | 48 |
| Sun 28 Jun | 104 | 67.3% | 40.1% | 12.3% | 22.2% | 48 |
| Mon 29 Jun | 161 | 49.1% | 21.4% | 11.8% | 35.2% | 48 |
| Tue 30 Jun | 209 | 37.9% | 10.5% | 9.6% | 47.6% | 48 |
What powered the grid
Each fuel's average share of the electricity generated in Great Britain in June 2026, with June 2025 beneath it for comparison. Imports count as one source, as NESO counts them.
Hours in each carbon band
- Very low (under 70 g): 112 hours, 15%
- Low (70–139 g): 283 hours, 39%
- Moderate (140–219 g): 285 hours, 40%
- High (220–299 g): 42 hours, 6%
Records in June 2026
- Cleanest half hour
- 38 g 12:30 on Saturday 13 June
- Dirtiest half hour
- 256 g 03:30 on Tuesday 30 June
- Most wind
- 69.2% 04:30 on Saturday 13 June
- Most solar
- 39.0% 12:30 on Sunday 14 June
- Most low-carbon
- 88.1% 14:00 on Sunday 28 June
- Least gas
- 5.3% 15:30 on Tuesday 9 June
- Cleanest day
- 58 g Saturday 13 June
- Dirtiest day
- 209 g Tuesday 30 June
- Windiest day
- 52.3% wind Thursday 4 June
- Sunniest day
- 16.0% solar Sunday 14 June
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 18 October 2026.