Alert archive / Pennsylvania / Berks County
Weather alerts in Berks County, Pennsylvania, 2023
220 weather alerts in 2023, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
Berks County and its neighbors
Each county as a circle sized by its count in 2023. Tap one for its archive.
- Alerts
- 220
- Warnings
- 66
- Watches
- 30
- Advisories
- 41
- Busiest month
- July72 alerts
- Busiest day
- July 9, 202318 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
1 of 5 tornado warnings covering Berks County in 2023 had a tornado report inside them; 0 of 1 tornado reports fell inside a warning.
Berks County, 2023
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 5 | 1 | 80% | 1 | 0% | |
| Severe thunderstorm warnings | 37 | 24 | 35% | 35 | 69% | 19 min |
| Flash flood warnings | 10 | 5 | 50% | 16 | 88% | 158 min |
Each office's whole area, 2023
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Philadelphia/Mount Holly: tornado warnings | 35 | 7 | 80% | 24 | 46% | 6 min |
| NWS Philadelphia/Mount Holly: severe thunderstorm warnings | 364 | 198 | 46% | 662 | 84% | 22 min |
| NWS Philadelphia/Mount Holly: flash flood warnings | 91 | 49 | 46% | 139 | 91% | 106 min |
An office's figures cover every county it serves, including across state lines.
Verified by the Iowa Environmental Mesonet's Cow, which matches each storm-based warning with the local storm reports inside its polygon while it was in force, within 15 km of its edge: a tornado warning counts as verified on a tornado report, a severe thunderstorm warning on hail of 1 inch or more, a gust of 58 mph or more, or wind damage, a flash flood warning on a flash flood report. The false alarm ratio is the share of warnings with no such report; "inside a warning" is the probability of detection, the share of reports that fell inside one; lead time runs from the warning's issue to each report inside it, counting zero for a report that came first. A warning with no report is not proof nothing happened: reports come from spotters, the public and damage surveys, and are thin where few people live.
The alerts
Every alert, in the order issued. Times are local, Eastern Time. Each opens its own page with the text, the map, the radar and the sounding.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Jan 3, 6:54 PM EST | Dense Fog Advisory | PHI | 16 hr |
| Jan 24, 4:04 AM EST | Winter Weather Advisory | PHI | 39 hr |
| Feb 21, 2:22 PM EST | Mesoscale Discussion | SPC | 53 min |
| Feb 21, 3:11 PM EST | Special Weather Statement | PHI | 49 min |
| Mar 2, 6:15 AM EST | Dense Fog Advisory | PHI | 4 hr |
| Mar 13, 2:56 PM EDT | Wind Advisory | PHI | 32 hr |
| Mar 25, 10:44 AM EDT | Special Weather Statement | PHI | 31 min |
| Mar 29, 9:57 PM EDT | Special Weather Statement | PHI | 48 min |
| Mar 31, 3:05 PM EDT | Wind Advisory | PHI | 35 hr |
| Apr 1, 2:27 PM EDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Apr 1, 5:27 PM EDT | Severe Thunderstorm Warning | PHI | 48 min |
| Apr 1, 5:53 PM EDT | Severe Thunderstorm Warning | PHI | 67 min |
| Apr 2, 11:40 AM EDT | Freeze Warning | PHI | 21 hr |
| Apr 7, 8:09 PM EDT | Freeze Watch | PHI | 7 hr |
| Apr 8, 3:31 AM EDT | Freeze Warning | PHI | 29 hr |
| Apr 9, 9:10 AM EDT | Freeze Warning | PHI | 24 hr |
| Apr 11, 3:46 PM EDT | Fire Weather Watch | PHI | 18 hr |
| Apr 12, 9:24 AM EDT | Red Flag Warning | PHI | 11 hr |
| Apr 16, 3:47 AM EDT | Dense Fog Advisory | PHI | 7 hr |
| Apr 22, 2:47 PM EDT | Mesoscale Discussion | SPC | 118 min |
| Apr 22, 3:04 PM EDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Apr 22, 4:16 PM EDT | Severe Thunderstorm Warning | PHI | 44 min |
| Apr 22, 4:49 PM EDT | Severe Thunderstorm Warning | PHI | 41 min |
| Apr 23, 7:51 PM EDT | Frost Advisory | PHI | 12 hr |
| Apr 24, 2:18 PM EDT | Frost Advisory | PHI | 18 hr |
| Apr 29, 3:46 PM EDT | Flood Watch | PHI | 30 hr |
| Apr 30, 8:14 PM EDT | Areal Flood Advisory | PHI | 3 hr |
| May 17, 11:20 AM EDT | Frost Advisory | PHI | 21 hr |
| Jun 3, 5:17 PM EDT | Special Weather Statement | PHI | 43 min |
| Jun 3, 5:53 PM EDT | Special Weather Statement | PHI | 52 min |
| Jun 3, 6:05 PM EDT | Severe Thunderstorm Warning | PHI | 29 min |
| Jun 5, 3:23 PM EDT | Fire Weather Watch | PHI | 12 hr |
| Jun 6, 3:49 AM EDT | Red Flag Warning | PHI | 16 hr |
| Jun 6, 1:10 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 6, 2:28 PM EDT | Special Weather Statement | PHI | 32 min |
| Jun 6, 2:58 PM EDT | Special Weather Statement | PHI | 32 min |
| Jun 6, 4:00 PM EDT | Special Weather Statement | PHI | 30 min |
| Jun 6, 4:06 PM EDT | Special Weather Statement | PHI | 24 min |
| Jun 6, 4:13 PM EDT | Severe Thunderstorm Warning | PHI | 36 min |
| Jun 6, 5:45 PM EDT | Special Weather Statement | PHI | 30 min |
| Jun 14, 1:51 PM EDT | Special Weather Statement | PHI | 24 min |
| Jun 14, 2:07 PM EDT | Severe Thunderstorm Warning | PHI | 38 min |
| Jun 16, 11:10 AM EDT | Tornado Warning | PHI | 35 min |
| Jun 16, 11:20 AM EDT | Severe Thunderstorm Warning | PHI | 40 min |
| Jun 25, 4:51 PM EDT | Areal Flood Advisory | PHI | 3 hr |
| Jun 25, 5:56 PM EDT | Areal Flood Advisory | PHI | 3 hr |
| Jun 26, 3:33 AM EDT | Flood Watch | PHI | 23 hr |
| Jun 26, 9:37 AM EDT | Mesoscale Discussion | SPC | 83 min |
| Jun 26, 12:36 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 26, 1:11 PM EDT | Severe Thunderstorm Watch | SPC | 11 hr |
| Jun 26, 1:13 PM EDT | Severe Thunderstorm Warning | PHI | 47 min |
| Jun 26, 1:35 PM EDT | Severe Thunderstorm Warning | PHI | 40 min |
| Jun 26, 2:04 PM EDT | Severe Thunderstorm Warning | PHI | 41 min |
| Jun 26, 2:12 PM EDT | Tornado Warning | PHI | 21 min |
| Jun 26, 2:21 PM EDT | Severe Thunderstorm Warning | PHI | 54 min |
| Jun 26, 2:23 PM EDT | Areal Flood Advisory | PHI | 107 min |
| Jun 26, 2:32 PM EDT | Flash Flood Warning | PHI | 67 min |
| Jun 26, 3:22 PM EDT | Mesoscale Discussion | SPC | 113 min |
| Jun 26, 8:03 PM EDT | Mesoscale Discussion | SPC | 87 min |
| Jun 26, 9:18 PM EDT | Severe Thunderstorm Warning | PHI | 42 min |
| Jun 26, 10:54 PM EDT | Areal Flood Advisory | PHI | 3 hr |
| Jun 27, 3:02 AM EDT | Flood Watch | PHI | 46 min |
| Jun 27, 3:48 AM EDT | Flood Watch | PHI | 17 hr |
| Jun 27, 12:45 PM EDT | Special Weather Statement | PHI | 30 min |
| Jun 27, 2:21 PM EDT | Special Weather Statement | PHI | 24 min |
| Jun 27, 2:42 PM EDT | Areal Flood Advisory | PHI | 3 hr |
| Jun 27, 3:07 PM EDT | Severe Thunderstorm Warning | PHI | 38 min |
| Jul 2, 3:24 PM EDT | Mesoscale Discussion | SPC | 96 min |
| Jul 2, 4:31 PM EDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jul 2, 5:08 PM EDT | Severe Thunderstorm Warning | PHI | 52 min |
| Jul 2, 6:16 PM EDT | Tornado Warning | PHI | 29 min |
| Jul 2, 6:33 PM EDT | Tornado Warning | PHI | 27 min |
| Jul 2, 6:57 PM EDT | Tornado Warning | PHI | 9 min |
| Jul 2, 7:23 PM EDT | Areal Flood Advisory | PHI | 2 hr |
| Jul 2, 10:52 PM EDT | Areal Flood Advisory | PHI | 83 min |
| Jul 3, 2:55 PM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jul 6, 11:47 AM EDT | Areal Flood Advisory | PHI | 11 min |
| Jul 6, 11:48 AM EDT | Special Weather Statement | PHI | 27 min |
| Jul 6, 11:58 AM EDT | Flash Flood Warning | PHI | 3 hr |
| Jul 6, 12:04 PM EDT | Areal Flood Advisory | PHI | 3 hr |
| Jul 6, 12:36 PM EDT | Special Weather Statement | PHI | 24 min |
| Jul 7, 2:13 PM EDT | Areal Flood Advisory | PHI | 3 hr |
| Jul 7, 2:18 PM EDT | Special Weather Statement | PHI | 27 min |
| Jul 7, 2:26 PM EDT | Flash Flood Warning | PHI | 4 hr |
| Jul 8, 3:17 PM EDT | Flood Watch | PHI | 31 hr |
| Jul 9, 10:28 AM EDT | Mesoscale Discussion | SPC | 92 min |
| Jul 9, 11:06 AM EDT | Severe Thunderstorm Watch | SPC | 9 hr |
| Jul 9, 11:54 AM EDT | Areal Flood Advisory | PHI | 33 min |
| Jul 9, 12:27 PM EDT | Flash Flood Warning | PHI | 8 hr |
| Jul 9, 12:43 PM EDT | Areal Flood Advisory | PHI | 33 min |
| Jul 9, 1:16 PM EDT | Flash Flood Warning | PHI | 6 hr |
| Jul 9, 1:17 PM EDT | Special Weather Statement | PHI | 28 min |
| Jul 9, 1:20 PM EDT | Mesoscale Discussion | SPC | 85 min |
| Jul 9, 2:16 PM EDT | Areal Flood Advisory | PHI | 30 min |
| Jul 9, 2:41 PM EDT | Flash Flood Warning | PHI | 4 hr |
| Jul 9, 2:46 PM EDT | Flash Flood Warning | PHI | 6 hr |
| Jul 9, 3:01 PM EDT | Special Weather Statement | PHI | 29 min |
| Jul 9, 3:15 PM EDT | Severe Thunderstorm Warning | PHI | 30 min |
| Jul 9, 3:20 PM EDT | Special Weather Statement | PHI | 25 min |
| Jul 9, 3:27 PM EDT | Severe Thunderstorm Warning | PHI | 33 min |
| Jul 9, 3:41 PM EDT | Special Weather Statement | PHI | 34 min |
| Jul 9, 3:51 PM EDT | Flash Flood Warning | PHI | 6 hr |
| Jul 9, 7:04 PM EDT | Areal Flood Warning | PHI | 9 hr |
| Jul 9, 9:33 PM EDT | Areal Flood Warning | PHI | 6 hr |
| Jul 13, 2:36 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 14, 2:02 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 15, 3:44 AM EDT | Flood Watch | PHI | 38 hr |
| Jul 15, 3:35 PM EDT | Special Weather Statement | PHI | 25 min |
| Jul 15, 3:50 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 16, 12:50 AM EDT | Special Weather Statement | PHI | 25 min |
| Jul 16, 4:05 AM EDT | Flash Flood Warning | PHI | 6 hr |
| Jul 19, 4:48 PM EDT | Mesoscale Discussion | SPC | 87 min |
| Jul 20, 10:07 PM EDT | Mesoscale Discussion | SPC | 113 min |
| Jul 20, 10:28 PM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jul 21, 2:29 AM EDT | Special Weather Statement | PHI | 46 min |
| Jul 21, 2:32 AM EDT | Severe Thunderstorm Warning | PHI | 43 min |
| Jul 21, 2:42 AM EDT | Severe Thunderstorm Warning | PHI | 48 min |
| Jul 21, 3:13 AM EDT | Severe Thunderstorm Warning | PHI | 47 min |
| Jul 24, 4:55 PM EDT | Special Weather Statement | PHI | 35 min |
| Jul 24, 5:28 PM EDT | Special Weather Statement | PHI | 32 min |
| Jul 24, 5:52 PM EDT | Areal Flood Advisory | PHI | 3 hr |
| Jul 24, 5:58 PM EDT | Special Weather Statement | PHI | 17 min |
| Jul 24, 6:16 PM EDT | Special Weather Statement | PHI | 29 min |
| Jul 25, 10:58 AM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 25, 12:07 PM EDT | Special Weather Statement | PHI | 23 min |
| Jul 25, 12:13 PM EDT | Severe Thunderstorm Watch | SPC | 10 hr |
| Jul 25, 12:31 PM EDT | Special Weather Statement | PHI | 29 min |
| Jul 25, 12:33 PM EDT | Special Weather Statement | PHI | 27 min |
| Jul 25, 1:00 PM EDT | Special Weather Statement | PHI | 30 min |
| Jul 25, 1:03 PM EDT | Severe Thunderstorm Warning | PHI | 42 min |
| Jul 25, 1:27 PM EDT | Areal Flood Advisory | PHI | 3 hr |
| Jul 25, 2:21 PM EDT | Areal Flood Advisory | PHI | 2 hr |
| Jul 26, 3:32 AM EDT | Heat Advisory | PHI | 4 days |
| Jul 27, 11:40 AM EDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 27, 3:18 PM EDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jul 27, 4:46 PM EDT | Mesoscale Discussion | SPC | 89 min |
| Jul 29, 1:56 PM EDT | Mesoscale Discussion | SPC | 64 min |
| Jul 29, 2:48 PM EDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Jul 29, 4:45 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 4, 11:21 AM EDT | Mesoscale Discussion | SPC | 114 min |
| Aug 4, 12:10 PM EDT | Severe Thunderstorm Watch | SPC | 10 hr |
| Aug 4, 6:13 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 7, 2:31 PM EDT | Mesoscale Discussion | SPC | 59 min |
| Aug 7, 3:13 PM EDT | Tornado Watch | SPC | 8 hr |
| Aug 7, 5:01 PM EDT | Mesoscale Discussion | SPC | 89 min |
| Aug 7, 5:33 PM EDT | Severe Thunderstorm Warning | PHI | 57 min |
| Aug 7, 6:21 PM EDT | Severe Thunderstorm Warning | PHI | 69 min |
| Aug 7, 6:53 PM EDT | Severe Thunderstorm Warning | PHI | 52 min |
| Aug 7, 7:00 PM EDT | Areal Flood Advisory | PHI | 66 min |
| Aug 12, 3:06 PM EDT | Special Weather Statement | PHI | 24 min |
| Aug 12, 3:39 PM EDT | Special Weather Statement | PHI | 36 min |
| Aug 12, 3:49 PM EDT | Severe Thunderstorm Warning | PHI | 41 min |
| Aug 12, 5:38 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 12, 11:31 PM EDT | Special Weather Statement | PHI | 59 min |
| Aug 12, 11:47 PM EDT | Severe Thunderstorm Warning | PHI | 43 min |
| Aug 13, 12:06 AM EDT | Areal Flood Advisory | PHI | 3 hr |
| Aug 13, 12:24 AM EDT | Severe Thunderstorm Warning | PHI | 51 min |
| Aug 14, 3:40 PM EDT | Flood Watch | PHI | 13 hr |
| Aug 15, 2:34 AM EDT | Areal Flood Advisory | PHI | 3 hr |
| Aug 15, 2:44 AM EDT | Areal Flood Advisory | PHI | 3 hr |
| Aug 15, 3:36 PM EDT | Special Weather Statement | PHI | 24 min |
| Aug 15, 4:57 PM EDT | Severe Thunderstorm Warning | PHI | 30 min |
| Aug 17, 11:04 PM EDT | Mesoscale Discussion | SPC | 3 hr |
| Aug 18, 4:04 AM EDT | Special Weather Statement | PHI | 56 min |
| Aug 18, 4:36 AM EDT | Special Weather Statement | PHI | 24 min |
| Sep 4, 2:41 PM EDT | Heat Advisory | PHI | 3 days |
| Sep 7, 11:58 AM EDT | Mesoscale Discussion | SPC | 3 hr |
| Sep 7, 1:10 PM EDT | Severe Thunderstorm Warning | PHI | 33 min |
| Sep 7, 1:14 PM EDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Sep 7, 1:38 PM EDT | Severe Thunderstorm Warning | PHI | 19 min |
| Sep 7, 2:13 PM EDT | Severe Thunderstorm Warning | PHI | 47 min |
| Sep 7, 3:06 PM EDT | Mesoscale Discussion | SPC | 84 min |
| Sep 7, 4:35 PM EDT | Special Weather Statement | PHI | 25 min |
| Sep 7, 4:47 PM EDT | Severe Thunderstorm Warning | PHI | 43 min |
| Sep 7, 4:48 PM EDT | Mesoscale Discussion | SPC | 87 min |
| Sep 7, 5:17 PM EDT | Severe Thunderstorm Warning | PHI | 43 min |
| Sep 7, 5:30 PM EDT | Severe Thunderstorm Warning | PHI | 31 min |
| Sep 7, 5:44 PM EDT | Severe Thunderstorm Warning | PHI | 46 min |
| Sep 7, 6:13 PM EDT | Mesoscale Discussion | SPC | 92 min |
| Sep 7, 7:36 PM EDT | Severe Thunderstorm Warning | PHI | 39 min |
| Sep 7, 7:51 PM EDT | Mesoscale Discussion | SPC | 84 min |
| Sep 7, 9:17 PM EDT | Special Weather Statement | CTP | 13 min |
| Sep 7, 9:19 PM EDT | Special Weather Statement | PHI | 26 min |
| Sep 7, 9:37 PM EDT | Severe Thunderstorm Warning | PHI | 18 min |
| Sep 7, 10:07 PM EDT | Special Weather Statement | PHI | 38 min |
| Sep 7, 10:38 PM EDT | Areal Flood Advisory | PHI | 76 min |
| Sep 7, 10:44 PM EDT | Special Weather Statement | PHI | 61 min |
| Sep 8, 2:46 PM EDT | Mesoscale Discussion | SPC | 119 min |
| Sep 8, 3:11 PM EDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Sep 8, 6:34 PM EDT | Mesoscale Discussion | SPC | 86 min |
| Sep 8, 10:33 PM EDT | Special Weather Statement | PHI | 27 min |
| Sep 9, 2:08 PM EDT | Mesoscale Discussion | SPC | 3 hr |
| Sep 9, 4:23 PM EDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Sep 9, 5:36 PM EDT | Special Weather Statement | PHI | 24 min |
| Sep 9, 6:06 PM EDT | Mesoscale Discussion | SPC | 114 min |
| Sep 9, 7:24 PM EDT | Special Weather Statement | PHI | 36 min |
| Sep 9, 7:56 PM EDT | Special Weather Statement | PHI | 64 min |
| Sep 9, 8:08 PM EDT | Mesoscale Discussion | SPC | 2 hr |
| Sep 9, 8:09 PM EDT | Areal Flood Advisory | PHI | 20 min |
| Sep 9, 8:29 PM EDT | Flash Flood Warning | PHI | 2 hr |
| Sep 9, 9:12 PM EDT | Areal Flood Advisory | PHI | 116 min |
| Sep 10, 7:11 PM EDT | Areal Flood Advisory | PHI | 3 hr |
| Sep 12, 2:39 PM EDT | Flood Watch | PHI | 16 hr |
| Oct 20, 8:54 PM EDT | Areal Flood Advisory | PHI | 48 min |
| Oct 23, 3:28 PM EDT | Frost Advisory | PHI | 18 hr |
| Oct 30, 3:03 AM EDT | Frost Advisory | PHI | 30 hr |
| Oct 31, 3:10 AM EDT | Freeze Watch | PHI | 24 hr |
| Nov 1, 3:16 AM EDT | Freeze Warning | PHI | 31 hr |
| Nov 28, 6:40 AM EST | Special Weather Statement | PHI | 50 min |
| Dec 2, 5:05 AM EST | Dense Fog Advisory | PHI | 5 hr |
| Dec 8, 3:26 PM EST | Flood Watch | PHI | 66 hr |
| Dec 11, 1:34 AM EST | Areal Flood Warning | PHI | 7 hr |
| Dec 15, 3:36 PM EST | Flood Watch | PHI | 69 hr |
| Dec 18, 4:41 AM EST | Areal Flood Warning | PHI | 14 hr |
| Dec 18, 8:31 AM EST | River Flood Warning | PHI | 11 hr |
| Dec 18, 2:26 PM EST | River Flood Warning | PHI | 12 hr |
| Dec 25, 3:20 PM EST | Dense Fog Advisory | PHI | 21 hr |
| Dec 27, 11:38 AM EST | Flood Watch | PHI | 22 hr |
| Dec 27, 9:12 PM EST | Areal Flood Warning | PHI | 8 hr |
| Dec 28, 1:12 AM EST | Areal Flood Warning | PHI | 8 hr |
By product
Every kind of product issued here, grouped by hazard. Each opens the same place narrowed to that product.
| Product | Alerts |
|---|---|
| Severe storms | |
| Severe Thunderstorm Warning | 37 |
| Tornado Warning | 5 |
| Severe Thunderstorm Watch | 14 |
| Tornado Watch | 1 |
| Mesoscale Discussion | 36 |
| Special Weather Statement | 47 |
| Flooding | |
| Areal Flood Warning | 6 |
| Flash Flood Warning | 10 |
| River Flood Warning | 2 |
| Flood Watch | 11 |
| Areal Flood Advisory | 26 |
| Winter | |
| Winter Weather Advisory | 1 |
| Heat | |
| Heat Advisory | 2 |
| Cold | |
| Freeze Warning | 4 |
| Freeze Watch | 2 |
| Frost Advisory | 5 |
| Wind and dust | |
| Wind Advisory | 2 |
| Fire | |
| Red Flag Warning | 2 |
| Fire Weather Watch | 2 |
| Fog and smoke | |
| Dense Fog Advisory | 5 |
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive20222024
Sources
National Weather Service watches, warnings, advisories and statements from the Iowa Environmental Mesonet's VTEC archive, which reconstructs tornado, severe thunderstorm, flash flood and marine warnings back to 1986 from the NWS text archive. Storm Prediction Center watches and mesoscale discussions from SPC's archive through the Mesonet. County centers from the US Census Bureau. Warning verification from the Mesonet's Cow. Rebuilt daily.