WhenToBird

Ardea herodias · Ardeidae

When Do Great Blue Herons Arrive in California?

Adult Great Blue Heron
Photo: mostbittern, CC BY 4.0 via iNaturalist

The Great Blue Heron is in California all year. It turns up on about 19% of checklists at its peak (late August) and on 11% in its quietest week (early April).

When to look

PresentAll year
Peak weekAug 22-31late August
Quietest weekApr 1-7early April

Best: late August. Here all year. Peak: on about 19% of California checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marcommon
  4. Aprcommon
  5. Maycommon
  6. Juncommon
  7. Julpeak season
  8. Augpeak season
  9. Seppeak season
  10. Octpeak season
  11. Novpeak season
  12. Decpeak season

Darker months: more checklists report it. Outlined: peak month.

0%5%10%15%20%Jan 1-7: 17% of 112336 checklistsJan 8-14: 17% of 85518 checklistsJan 15-21: 17% of 86488 checklistsJan 22-31: 16% of 116174 checklistsFeb 1-7: 15% of 75171 checklistsFeb 8-14: 13% of 84467 checklistsFeb 15-21: 12% of 105683 checklistsFeb 22-28: 14% of 83396 checklistsMar 1-7: 13% of 77470 checklistsMar 8-14: 12% of 75180 checklistsMar 15-21: 12% of 80770 checklistsMar 22-31: 11% of 114116 checklistsApr 1-7: 11% of 84057 checklistsApr 8-14: 11% of 83692 checklistsApr 15-21: 12% of 89242 checklistsApr 22-30: 12% of 114289 checklistsMay 1-7: 12% of 85728 checklistsMay 8-14: 12% of 91984 checklistsMay 15-21: 12% of 75478 checklistsMay 22-31: 12% of 106250 checklistsJun 1-7: 12% of 70051 checklistsJun 8-14: 13% of 67485 checklistsJun 15-21: 13% of 66269 checklistsJun 22-30: 14% of 79172 checklistsJul 1-7: 15% of 62877 checklistsJul 8-14: 15% of 60328 checklistsJul 15-21: 16% of 59705 checklistsJul 22-31: 17% of 83796 checklistsAug 1-7: 18% of 60215 checklistsAug 8-14: 19% of 60172 checklistsAug 15-21: 19% of 59877 checklistsAug 22-31: 20% of 89107 checklistsSep 1-7: 19% of 72000 checklistsSep 8-14: 18% of 71228 checklistsSep 15-21: 17% of 76808 checklistsSep 22-30: 17% of 100204 checklistsOct 1-7: 16% of 76571 checklistsOct 8-14: 17% of 80874 checklistsOct 15-21: 17% of 74581 checklistsOct 22-31: 17% of 97498 checklistsNov 1-7: 18% of 70851 checklistsNov 8-14: 18% of 72431 checklistsNov 15-21: 18% of 66767 checklistsNov 22-30: 18% of 94737 checklistsDec 1-7: 18% of 65393 checklistsDec 8-14: 17% of 67449 checklistsDec 15-21: 15% of 83421 checklistsDec 22-31: 16% of 124993 checklistsJanFebMarAprMayJunJulAugSepOctNovDec
Share of complete checklists reporting it, by week (4 per month). Grey bars: fewer than 10 checklists, not counted.

Frequency is the share of complete checklists in California that listed the bird, 2016–2025. It is not a head count, and it follows where and when people go birding. How to read it.

JanFebMarAprMayJunJulAugSepOctNovDec
today
Second week of November

Each county is shaded by the share of complete checklists there that listed the bird, blended with the weeks either side. Darker is more often. It follows where people watch birds, not how many birds there are. How to read it.

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Where in California

Best counties

Share of checklists at the peak
  1. Colusa CountyBest late November · 251 checklists that week, 7,653 in all51%
  2. Sutter CountyBest late October · 127 checklists that week, 4,996 in all46%
  3. Imperial CountyBest late June · 300 checklists that week, 24,551 in all39%
  4. Lake CountyBest the second week of December · 217 checklists that week, 12,989 in all38%
  5. Glenn CountyBest the second week of October · 47 checklists that week, 5,189 in all36%
  6. Kings CountyBest late September · 123 checklists that week, 3,688 in all33%

Best spots

Share of checklists at the peak
  1. Ranch Jurupa Regional ParkRiverside County, best early December · 20 checklists that week, 855 in all97%
  2. Piute PondsLos Angeles County, best the second week of August · 21 checklists that week, 1,269 in all97%
  3. Santa Clara RiverVentura County, best the second week of September · 128 checklists that week, 5,820 in all96%
  4. Abbotts LagoonMarin County, best mid July · 49 checklists that week, 2,610 in all96%
  5. Glen Helen Regional ParkSan Bernardino County, best early November · 22 checklists that week, 814 in all95%

Busy spots report more of everything; compare the checklist counts before you drive anywhere.

Best time of day

In California, the Great Blue Heron is most often listed on checklists started between 7 and 9 am (17% of those checklists).

0%5%10%15%20%12 am: too few checklists (1688) to judge1 am: too few checklists (1451) to judge2 am: too few checklists (1402) to judge3 am: too few checklists (1743) to judge4 am: too few checklists (4647) to judge5 am: too few checklists (32158) to judge6 am: 17% of 186053 checklists7 am: 17% of 444086 checklists8 am: 17% of 535846 checklists9 am: 16% of 486061 checklists10 am: 15% of 411130 checklists11 am: 14% of 325798 checklists12 pm: 14% of 269132 checklists1 pm: 14% of 244762 checklists2 pm: 14% of 235420 checklists3 pm: 14% of 232365 checklists4 pm: 13% of 208688 checklists5 pm: 12% of 146104 checklists6 pm: 11% of 96867 checklists7 pm: too few checklists (50942) to judge8 pm: too few checklists (14803) to judge9 pm: too few checklists (5561) to judge10 pm: too few checklists (3546) to judge11 pm: too few checklists (2092) to judge12a3a6a9a12p3p6p9p
Share of checklists started in each local hour that reported it. It reflects when people go birding as well as when birds are active. Grey hours have too few checklists (under 2% of the state’s, or under 200) to judge.
Week-by-week table
MonthDays 1-78-1415-2122-end
January17%17%17%16%
February15%13%12%14%
March13%12%12%11%
April11%11%12%12%
May12%12%12%12%
June12%13%13%14%
July15%15%16%17%
August18%19%19%20%
September19%18%17%17%
October16%17%17%17%
November18%18%18%18%
December18%17%15%16%

Neighboring states

  • Nevada: all year, most in fall, peaks early September
  • Utah: year-round, peaks early September
  • Arizona: year-round, peaks late November
  • Oregon: year-round, peaks early September

Common questions

When do Great Blue Herons arrive in California?
The Great Blue Heron is in California all year. It turns up on about 19% of checklists at its peak (late August) and on 11% in its quietest week (early April).
When do Great Blue Herons leave California?
The Great Blue Heron does not leave California: it is reported all year, from 11% of checklists in early April to 19% in late August.
When is the best time to see a Great Blue Heron in California?
The Great Blue Heron is reported most often in late August, on about 19% of California checklists.
Where in California are Great Blue Herons seen most often?
By county, Colusa County, Sutter County, and Imperial County have the highest peak reporting rates for the Great Blue Heron (counties with at least 200 checklists).