Alert archive / California / Severe Thunderstorm Warnings

Severe Thunderstorm Warnings in California, 2015

141 severe thunderstorm warnings in 2015. An alert counts here when it covered any part of the state, so the counties below add up to more than the state. The archive of severe thunderstorm warnings reaches back to 1986.

Severe Thunderstorm Warnings by county

Each county as a circle sized by its count in 2015. Tap one for its archive.

Severe Thunderstorm Warnings: 141
Busiest month: July64 severe thunderstorm warnings
Busiest day: July 21, 201511 severe thunderstorm warnings

Over time

By month

Warning verification

How often warnings here had a storm report inside them, and how much warning the reports had.

24 of 141 severe thunderstorm warnings covering California in 2015 had a qualifying storm report inside them; 36 of 77 hail, wind and damage reports fell inside a warning, on average 23 minutes after it went out.

California, 2015

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
Severe thunderstorm warnings	141	24	83%	77	47%	23 min

Each office's whole area, 2015

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
NWS Hanford, CA: severe thunderstorm warnings	12	1	92%	10	20%	23 min
NWS Phoenix, AZ: severe thunderstorm warnings	85	30	65%	153	52%	15 min
NWS San Diego, CA: severe thunderstorm warnings	18	6	67%	24	58%	30 min
NWS Los Angeles, CA: severe thunderstorm warnings	9	2	78%	4	100%	47 min
NWS Medford, OR: severe thunderstorm warnings	37	4	89%	12	50%	15 min
NWS San Francisco Bay Area, CA: severe thunderstorm warnings	1	0	100%	0
NWS Las Vegas, NV: severe thunderstorm warnings	66	16	76%	81	43%	22 min
NWS Sacramento, CA: severe thunderstorm warnings	21	3	86%	13	38%	10 min
NWS Eureka, CA: severe thunderstorm warnings	5	1	80%	1	100%	16 min
NWS Reno, NV: severe thunderstorm warnings	45	6	87%	26	38%	11 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, Pacific Time. Each opens its own page with the text, the map, the radar and the sounding.

Issued	Product	Office	Counties	Lasted
Feb 27, 3:58 PM PST	Severe Thunderstorm Warning	STO	Butte, Glenn	62 min
Feb 28, 6:27 PM PST	Severe Thunderstorm Warning	MTR	San Mateo	21 min
Mar 18, 7:09 PM PDT	Severe Thunderstorm Warning	LOX	Los Angeles	36 min
Mar 18, 7:45 PM PDT	Severe Thunderstorm Warning	LOX	Los Angeles	33 min
Apr 7, 12:58 PM PDT	Severe Thunderstorm Warning	STO	Amador, Calaveras, Sacramento, San Joaquin	58 min
Apr 7, 2:00 PM PDT	Severe Thunderstorm Warning	STO	Placer, Sacramento, Sutter, Yolo	26 min
Apr 7, 2:25 PM PDT	Severe Thunderstorm Warning	STO	El Dorado, Placer, Sacramento, Sutter, Yolo	65 min
Apr 7, 2:30 PM PDT	Severe Thunderstorm Warning	STO	Glenn, Tehama	45 min
Apr 7, 4:30 PM PDT	Severe Thunderstorm Warning	HNX	Madera, Merced	30 min
Apr 7, 4:31 PM PDT	Severe Thunderstorm Warning	HNX	Fresno, Kings	29 min
Apr 23, 7:52 PM PDT	Severe Thunderstorm Warning	STO	Butte, Colusa, Glenn	38 min
May 25, 2:38 PM PDT	Severe Thunderstorm Warning	REV	Lassen, Plumas	37 min
May 25, 4:29 PM PDT	Severe Thunderstorm Warning	EKA	Trinity	31 min
May 25, 5:20 PM PDT	Severe Thunderstorm Warning	EKA	Trinity	25 min
Jun 5, 3:27 PM PDT	Severe Thunderstorm Warning	STO	Tuolumne	48 min
Jun 5, 4:59 PM PDT	Severe Thunderstorm Warning	STO	El Dorado	46 min
Jun 5, 5:46 PM PDT	Severe Thunderstorm Warning	STO	El Dorado	29 min
Jun 6, 3:12 PM PDT	Severe Thunderstorm Warning	STO	El Dorado, Placer	33 min
Jun 9, 4:13 AM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	19 min
Jun 9, 3:57 PM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	48 min
Jun 9, 4:57 PM PDT	Severe Thunderstorm Warning	STO	Shasta	48 min
Jun 10, 3:38 PM PDT	Severe Thunderstorm Warning	LOX	San Luis Obispo	52 min
Jun 10, 3:57 PM PDT	Severe Thunderstorm Warning	HNX	Fresno, Tulare	48 min
Jun 10, 5:07 PM PDT	Severe Thunderstorm Warning	HNX	Kern	38 min
Jun 12, 5:42 PM PDT	Severe Thunderstorm Warning	HNX	Tulare	33 min
Jun 27, 4:53 PM PDT	Severe Thunderstorm Warning	REV	Sierra	22 min
Jun 27, 5:05 PM PDT	Severe Thunderstorm Warning	REV	Alpine, Mono	40 min
Jun 27, 5:18 PM PDT	Severe Thunderstorm Warning	REV	Lassen, Sierra	42 min
Jun 27, 5:38 PM PDT	Severe Thunderstorm Warning	REV	El Dorado, Placer	37 min
Jun 27, 6:29 PM PDT	Severe Thunderstorm Warning	REV	Lassen	61 min
Jun 30, 1:53 PM PDT	Severe Thunderstorm Warning	SGX	San Diego	52 min
Jun 30, 2:00 PM PDT	Severe Thunderstorm Warning	SGX	Riverside, San Diego	60 min
Jun 30, 2:01 PM PDT	Severe Thunderstorm Warning	SGX	Riverside, San Diego	59 min
Jun 30, 2:08 PM PDT	Severe Thunderstorm Warning	SGX	San Diego	34 min
Jun 30, 10:40 PM PDT	Severe Thunderstorm Warning	VEF	San Bernardino	50 min
Jul 1, 12:01 AM PDT	Severe Thunderstorm Warning	VEF	San Bernardino	59 min
Jul 1, 4:19 PM PDT	Severe Thunderstorm Warning	REV	Alpine, Mono	41 min
Jul 1, 5:36 PM PDT	Severe Thunderstorm Warning	HNX	Fresno, Madera, Mariposa	24 min
Jul 2, 5:31 PM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	15 min
Jul 2, 5:52 PM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	23 min
Jul 3, 4:04 PM PDT	Severe Thunderstorm Warning	REV	Lassen, Plumas	26 min
Jul 4, 5:36 PM PDT	Severe Thunderstorm Warning	EKA	Trinity	28 min
Jul 5, 1:52 PM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	38 min
Jul 5, 3:26 PM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	25 min
Jul 5, 3:52 PM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	23 min
Jul 5, 4:12 PM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	33 min
Jul 5, 5:42 PM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	33 min
Jul 5, 5:54 PM PDT	Severe Thunderstorm Warning	MFR	Modoc	36 min
Jul 5, 6:18 PM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	27 min
Jul 6, 2:31 PM PDT	Severe Thunderstorm Warning	REV	Alpine, Mono	44 min
Jul 6, 4:23 PM PDT	Severe Thunderstorm Warning	VEF	San Bernardino	22 min
Jul 7, 2:10 PM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	35 min
Jul 7, 2:10 PM PDT	Severe Thunderstorm Warning	REV	Nevada, Sierra	35 min
Jul 7, 2:49 PM PDT	Severe Thunderstorm Warning	REV	Lassen, Plumas, Sierra	41 min
Jul 7, 4:47 PM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	28 min
Jul 7, 5:04 PM PDT	Severe Thunderstorm Warning	STO	Plumas	41 min
Jul 7, 5:11 PM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	21 min
Jul 8, 12:23 PM PDT	Severe Thunderstorm Warning	STO	Alpine, Amador, El Dorado	24 min
Jul 8, 12:41 PM PDT	Severe Thunderstorm Warning	REV	Alpine, El Dorado, Placer	49 min
Jul 8, 1:02 PM PDT	Severe Thunderstorm Warning	REV	Plumas	28 min
Jul 8, 1:58 PM PDT	Severe Thunderstorm Warning	REV	Plumas	47 min
Jul 8, 2:33 PM PDT	Severe Thunderstorm Warning	STO	Plumas, Shasta, Tehama	42 min
Jul 8, 3:06 PM PDT	Severe Thunderstorm Warning	REV	Lassen, Sierra	39 min
Jul 8, 4:24 PM PDT	Severe Thunderstorm Warning	REV	Lassen	36 min
Jul 8, 5:50 PM PDT	Severe Thunderstorm Warning	EKA	Trinity	40 min
Jul 9, 12:50 PM PDT	Severe Thunderstorm Warning	REV	Nevada, Placer, Sierra	25 min
Jul 9, 1:56 PM PDT	Severe Thunderstorm Warning	REV	Lassen, Plumas	49 min
Jul 9, 7:12 PM PDT	Severe Thunderstorm Warning	MFR	Modoc	33 min
Jul 16, 3:59 PM PDT	Severe Thunderstorm Warning	REV	Nevada, Placer	46 min
Jul 17, 5:54 PM PDT	Severe Thunderstorm Warning	VEF	San Bernardino	36 min
Jul 17, 10:27 PM PDT	Severe Thunderstorm Warning	VEF	San Bernardino	48 min
Jul 18, 11:37 AM PDT	Severe Thunderstorm Warning	PSR	Riverside	38 min
Jul 18, 1:27 PM PDT	Severe Thunderstorm Warning	VEF	San Bernardino	58 min
Jul 18, 1:43 PM PDT	Severe Thunderstorm Warning	PSR	Imperial	32 min
Jul 18, 1:44 PM PDT	Severe Thunderstorm Warning	VEF	San Bernardino	61 min
Jul 19, 1:55 PM PDT	Severe Thunderstorm Warning	SGX	Riverside	65 min
Jul 20, 3:41 PM PDT	Severe Thunderstorm Warning	STO	Alpine, Amador, Calaveras, El Dorado, Tuolumne	64 min
Jul 20, 5:16 PM PDT	Severe Thunderstorm Warning	STO	Plumas	29 min
Jul 20, 6:17 PM PDT	Severe Thunderstorm Warning	HNX	Fresno, Madera	28 min
Jul 20, 6:42 PM PDT	Severe Thunderstorm Warning	STO	Sierra	27 min
Jul 20, 7:29 PM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	31 min
Jul 21, 12:51 PM PDT	Severe Thunderstorm Warning	REV	Alpine, El Dorado	39 min
Jul 21, 1:12 PM PDT	Severe Thunderstorm Warning	REV	Nevada, Placer	48 min
Jul 21, 1:58 PM PDT	Severe Thunderstorm Warning	REV	Nevada, Placer	47 min
Jul 21, 2:08 PM PDT	Severe Thunderstorm Warning	MFR	Modoc	22 min
Jul 21, 3:02 PM PDT	Severe Thunderstorm Warning	REV	Plumas	28 min
Jul 21, 3:36 PM PDT	Severe Thunderstorm Warning	REV	Lassen, Plumas	54 min
Jul 21, 3:46 PM PDT	Severe Thunderstorm Warning	REV	El Dorado, Placer	44 min
Jul 29, 3:40 PM PDT	Severe Thunderstorm Warning	SGX	Riverside	65 min
Jul 29, 4:50 PM PDT	Severe Thunderstorm Warning	VEF	San Bernardino	25 min
Jul 29, 5:23 PM PDT	Severe Thunderstorm Warning	SGX	San Diego	52 min
Jul 29, 5:34 PM PDT	Severe Thunderstorm Warning	SGX	San Bernardino	34 min
Jul 29, 5:49 PM PDT	Severe Thunderstorm Warning	VEF	San Bernardino	41 min
Jul 30, 3:02 PM PDT	Severe Thunderstorm Warning	VEF	San Bernardino	58 min
Jul 30, 3:12 PM PDT	Severe Thunderstorm Warning	LOX	Los Angeles, Ventura	48 min
Jul 30, 3:20 PM PDT	Severe Thunderstorm Warning	VEF	San Bernardino	55 min
Jul 30, 3:52 PM PDT	Severe Thunderstorm Warning	LOX	Ventura	53 min
Jul 30, 4:59 PM PDT	Severe Thunderstorm Warning	SGX	Riverside, San Bernardino	61 min
Aug 1, 2:42 PM PDT	Severe Thunderstorm Warning	STO	Alpine, Tuolumne	33 min
Aug 1, 3:17 PM PDT	Severe Thunderstorm Warning	STO	Alpine, Tuolumne	58 min
Aug 1, 4:06 PM PDT	Severe Thunderstorm Warning	STO	Alpine	54 min
Aug 1, 5:24 PM PDT	Severe Thunderstorm Warning	REV	Plumas	51 min
Aug 1, 5:56 PM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	34 min
Aug 1, 7:06 PM PDT	Severe Thunderstorm Warning	REV	Lassen, Plumas	39 min
Aug 1, 7:45 PM PDT	Severe Thunderstorm Warning	REV	Lassen, Plumas	36 min
Aug 4, 7:05 PM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	21 min
Aug 4, 7:32 PM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	28 min
Aug 4, 7:57 PM PDT	Severe Thunderstorm Warning	MFR	Siskiyou	33 min
Aug 6, 2:47 PM PDT	Severe Thunderstorm Warning	PSR	Riverside	28 min
Aug 6, 3:14 PM PDT	Severe Thunderstorm Warning	PSR	Riverside	16 min
Aug 6, 7:26 PM PDT	Severe Thunderstorm Warning	PSR	Imperial, Riverside	19 min
Aug 6, 7:38 PM PDT	Severe Thunderstorm Warning	SGX	Riverside, San Diego	52 min
Aug 6, 8:18 PM PDT	Severe Thunderstorm Warning	SGX	Riverside	42 min
Aug 6, 9:27 PM PDT	Severe Thunderstorm Warning	PSR	Riverside, San Bernardino	33 min
Aug 6, 9:37 PM PDT	Severe Thunderstorm Warning	VEF	San Bernardino	53 min
Aug 26, 2:01 PM PDT	Severe Thunderstorm Warning	PSR	Riverside, San Bernardino	29 min
Aug 26, 2:29 PM PDT	Severe Thunderstorm Warning	VEF	San Bernardino	46 min
Sep 8, 2:49 PM PDT	Severe Thunderstorm Warning	SGX	San Diego	56 min
Sep 8, 4:35 PM PDT	Severe Thunderstorm Warning	SGX	Riverside	55 min
Sep 8, 6:25 PM PDT	Severe Thunderstorm Warning	SGX	San Bernardino	65 min
Sep 9, 1:30 PM PDT	Severe Thunderstorm Warning	SGX	Riverside	60 min
Sep 9, 2:10 PM PDT	Severe Thunderstorm Warning	SGX	Riverside, San Bernardino	65 min
Oct 4, 4:52 PM PDT	Severe Thunderstorm Warning	VEF	Inyo	27 min
Oct 5, 3:56 AM PDT	Severe Thunderstorm Warning	VEF	Inyo	20 min
Oct 14, 11:25 PM PDT	Severe Thunderstorm Warning	SGX	San Bernardino	50 min
Oct 14, 11:31 PM PDT	Severe Thunderstorm Warning	LOX	Los Angeles	59 min
Oct 15, 2:16 AM PDT	Severe Thunderstorm Warning	PSR	Riverside	44 min
Oct 15, 2:48 PM PDT	Severe Thunderstorm Warning	LOX	Los Angeles	72 min
Oct 15, 3:00 PM PDT	Severe Thunderstorm Warning	HNX	Kern	30 min
Oct 15, 3:30 PM PDT	Severe Thunderstorm Warning	HNX	Kern	30 min
Oct 15, 3:39 PM PDT	Severe Thunderstorm Warning	HNX	Kern	36 min
Oct 15, 3:43 PM PDT	Severe Thunderstorm Warning	SGX	San Bernardino	35 min
Oct 15, 4:01 PM PDT	Severe Thunderstorm Warning	LOX	Los Angeles	89 min
Oct 15, 5:29 PM PDT	Severe Thunderstorm Warning	LOX	Los Angeles	73 min
Oct 15, 6:11 PM PDT	Severe Thunderstorm Warning	HNX	Kern	34 min
Oct 18, 1:23 AM PDT	Severe Thunderstorm Warning	VEF	Inyo	37 min
Oct 18, 1:53 AM PDT	Severe Thunderstorm Warning	VEF	Inyo	37 min
Oct 18, 2:18 PM PDT	Severe Thunderstorm Warning	VEF	San Bernardino	42 min
Nov 15, 2:27 PM PST	Severe Thunderstorm Warning	HNX	Merced	33 min
Nov 15, 2:32 PM PST	Severe Thunderstorm Warning	STO	El Dorado	43 min
Dec 10, 12:09 PM PST	Severe Thunderstorm Warning	EKA	Humboldt	21 min

The busiest days

Days with the most alerts issued, by UTC date.

Nearby

Alerts in force now Tornadoes on record The radar archive 2014 2016

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.