Environment Agency062WAF28UpColneHerts and North London
Upper River Colne and Radlett Brook: flood history since 2009
The Environment Agency has issued 116 flood alerts for Upper River Colne and Radlett Brook since 10 Feb 2009, most often in January; the busiest year was 2024 (19). The history file ends in June 2026; AreaZine's record of the live feed adds 2 since 1 July 2026.
Flood alerts only
The flood area
- Flood area
- Upper River Colne and Radlett Brook
- Code
- 062WAF28UpColne
- Environment Agency area
- Herts and North London
- County
- Hertfordshire
- River or sea
- River Colne
- First in the history
- 10 Feb 2009
- Latest in the history file
- 12 Mar 2026
- Latest in AreaZine's record
- Flood alert, 27 Aug 2026
- Current status
- check-for-flooding.service.gov.uk (the Environment Agency's live page)
Flood alert, flood warning, severe flood warning: what each means
Source: Environment Agency, Historic Flood Warnings (England); Environment Agency flood-monitoring API. Contains public sector information licensed under the Open Government Licence v3.0.
The latest: since 1 July 2026, in AreaZine's record of the live feed
| Date | Level |
|---|---|
| 27 Aug 2026 | Flood alert |
| 26 Aug 2026 | Flood alert |
How many alerts and warnings a year?
Flood alerts, flood warnings and severe flood warnings (updates not counted), by year. 2026 runs to the end of June.
The numbers
| Year | Alerts | Warnings | Severe |
|---|---|---|---|
| 2026 | 8 | 0 | 0 |
| 2025 | 7 | 0 | 0 |
| 2024 | 19 | 0 | 0 |
| 2023 | 11 | 0 | 0 |
| 2022 | 5 | 0 | 0 |
| 2021 | 7 | 0 | 0 |
| 2020 | 11 | 0 | 0 |
| 2019 | 5 | 0 | 0 |
| 2018 | 4 | 0 | 0 |
| 2017 | 5 | 0 | 0 |
| 2016 | 7 | 0 | 0 |
| 2015 | 6 | 0 | 0 |
| 2014 | 6 | 0 | 0 |
| 2013 | 6 | 0 | 0 |
| 2012 | 8 | 0 | 0 |
| 2011 | 1 | 0 | 0 |
Source: Environment Agency, Historic Flood Warnings (England); Environment Agency flood-monitoring API. Contains public sector information licensed under the Open Government Licence v3.0.
When in the year?
All alerts and warnings since 2009 by month.
Source: Environment Agency, Historic Flood Warnings (England); Environment Agency flood-monitoring API. Contains public sector information licensed under the Open Government Licence v3.0.
Before July 2026: the latest in the history file
| Date | Level |
|---|---|
| 12 Mar 2026 | Flood alert |
| 18 Feb 2026 | Flood alert |
| 14 Feb 2026 | Flood alert |
| 5 Feb 2026 | Flood alert |
| 26 Jan 2026 | Flood alert |
| 20 Jan 2026 | Flood alert |
| 15 Jan 2026 | Flood alert |
| 8 Jan 2026 | Flood alert |
| 18 Dec 2025 | Flood alert |
| 5 Dec 2025 | Flood alert |
| 13 Nov 2025 | Flood alert |
| 19 Jul 2025 | Flood alert |
Source: Environment Agency, Historic Flood Warnings (England); Environment Agency flood-monitoring API. Contains public sector information licensed under the Open Government Licence v3.0.