Huntington Beach State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Huntington Beach State Park clear sky chart from 2005-11-06 to 2024-11-11.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	11% 6% 2 6% 4 4 5% 4 7% 8% 42%	101119
	Night	11% 6% 2 6% 4 4 4 4 6% 8% 43%	98019
Transparency	Day	37% 8% 15% 20% 16% 5%	104766
	Night	37% 7% 13% 20% 17% 6%	102511
Seeing	Day	12% 3 15% 28% 30% 13%	15687
	Night	13% 4 19% 31% 27% 7%	25785

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	13% 5% 2 5% 3 3 4 4 6% 8% 46%	2836
	11th to 20th	Day	10% 5% 2 6% 5% 4 3 3 6% 9% 47%	2840
	21st to end	Day	13% 8% 3 7% 5% 4 4 3 3 5% 45%	3124
February	1st to 10th	Day	13% 7% 2 7% 4 5% 5% 4 5% 6% 41%	1710
	11th to 20th	Day	17% 7% 2 5% 4 3 3 3 5% 5% 46%	1763
	21st to end	Day	15% 6% 3 7% 4 4 3 4 5% 6% 43%	1727
March	1st to 10th	Day	20% 10% 3 7% 4 3 3 3 5% 6% 36%	3435
	11th to 20th	Day	8% 4 2 5% 4 4 5% 3 5% 8% 51%	3480
	21st to end	Day	15% 7% 2 6% 3 3 4 4 5% 6% 45%	3815
April	1st to 10th	Day	9% 5% 2 4 3 4 4 4 6% 7% 52%	2175
	11th to 20th	Day	9% 4 1 4 4 4 5% 3 6% 6% 54%	2254
	21st to end	Day	6% 5% 1 4 4 4 4 4 5% 8% 56%	2280
May	1st to 10th	Day	6% 5% 2 6% 5% 5% 5% 4 7% 10% 45%	3913
	11th to 20th	Day	12% 7% 3 6% 5% 4 4 4 6% 8% 40%	4081
	21st to end	Day	6% 3 1 4 3 4 5% 5% 8% 11% 48%	4476
June	1st to 10th	Day	8% 7% 2 7% 6% 5% 6% 5% 9% 11% 34%	2470
	11th to 20th	Day	9% 4 1 4 5% 5% 6% 5% 8% 11% 43%	2470
	21st to end	Day	6% 4 2 7% 5% 6% 6% 6% 11% 11% 36%	2470
July	1st to 10th	Day	12% 5% 2 7% 5% 6% 6% 5% 9% 11% 32%	4120
	11th to 20th	Day	7% 5% 2 7% 7% 6% 7% 6% 9% 12% 32%	4120
	21st to end	Day	7% 6% 2 8% 6% 6% 8% 6% 10% 12% 28%	4466
August	1st to 10th	Day	18% 7% 3 9% 6% 5% 5% 5% 8% 11% 23%	4104
	11th to 20th	Day	8% 5% 2 7% 5% 5% 6% 6% 8% 11% 38%	3835
	21st to end	Day	9% 6% 3 6% 4 4 5% 4 7% 9% 42%	4180
September	1st to 10th	Day	10% 5% 2 5% 5% 5% 4 5% 8% 11% 41%	2280
	11th to 20th	Day	15% 7% 2 6% 5% 4 5% 4 6% 8% 37%	2104
	21st to end	Day	14% 6% 3 7% 5% 5% 4 4 6% 8% 40%	2066
October	1st to 10th	Day	15% 6% 3 5% 4 4 4 3 4 6% 47%	1900
	11th to 20th	Day	9% 4 2 5% 3 3 3 3 4 5% 58%	1900
	21st to end	Day	9% 4 2 5% 3 3 3 2 6% 6% 56%	2090
November	1st to 10th	Day	13% 5% 1 4 3 3 4 3 5% 6% 53%	1957
	11th to 20th	Day	12% 6% 3 6% 5% 4 4 2 5% 5% 48%	1900
	21st to end	Day	11% 6% 3 6% 4 3 3 3 5% 6% 51%	1791
December	1st to 10th	Day	13% 7% 2 7% 4 4 6% 5% 6% 7% 39%	1710
	11th to 20th	Day	14% 4 2 5% 3 2 2 2 3 6% 56%	2153
	21st to end	Day	14% 9% 3 7% 4 4 4 3 5% 6% 40%	3124
January	1st to 10th	Night	13% 7% 2 6% 4 4 5% 4 6% 6% 43%	4109
	11th to 20th	Night	10% 7% 3 7% 4 5% 5% 5% 7% 8% 40%	4120
	21st to end	Night	12% 8% 3 8% 5% 4 4 3 4 6% 44%	4532
February	1st to 10th	Night	14% 7% 2 6% 4 4 3 3 6% 6% 44%	2470
	11th to 20th	Night	17% 8% 2 6% 4 3 4 3 5% 6% 42%	2299
	21st to end	Night	14% 7% 2 6% 4 4 4 3 6% 7% 42%	1727
March	1st to 10th	Night	20% 12% 4 8% 4 4 3 2 4 5% 33%	3418
	11th to 20th	Night	11% 5% 2 6% 4 4 4 4 6% 8% 48%	3480
	21st to end	Night	15% 5% 2 6% 4 3 4 3 6% 6% 47%	3817
April	1st to 10th	Night	9% 6% 2 6% 4 5% 4 3 6% 7% 49%	2004
	11th to 20th	Night	9% 5% 2 6% 4 4 4 4 5% 7% 49%	1875
	21st to end	Night	7% 4 2 5% 4 4 4 4 6% 8% 53%	1900
May	1st to 10th	Night	5% 5% 2 6% 4 4 5% 4 7% 10% 48%	3010
	11th to 20th	Night	11% 7% 3 6% 5% 4 4 4 5% 8% 42%	2812
	21st to end	Night	6% 4 2 5% 4 4 5% 4 8% 10% 49%	3079
June	1st to 10th	Night	8% 6% 3 7% 5% 5% 4 5% 8% 12% 36%	1710
	11th to 20th	Night	8% 6% 1 6% 5% 5% 5% 4 7% 10% 44%	1710
	21st to end	Night	6% 5% 2 6% 5% 5% 6% 5% 9% 16% 34%	1710
July	1st to 10th	Night	10% 5% 2 7% 6% 6% 7% 6% 8% 11% 31%	2840
	11th to 20th	Night	8% 6% 3 8% 5% 6% 7% 5% 9% 13% 32%	2840
	21st to end	Night	7% 5% 2 6% 5% 5% 7% 6% 11% 14% 30%	3087
August	1st to 10th	Night	17% 8% 3 7% 5% 5% 5% 5% 8% 12% 25%	2825
	11th to 20th	Night	7% 5% 2 5% 5% 6% 6% 5% 9% 13% 39%	2961
	21st to end	Night	7% 5% 2 6% 4 4 5% 5% 8% 9% 45%	3476
September	1st to 10th	Night	9% 5% 2 7% 6% 5% 6% 5% 6% 10% 39%	1900
	11th to 20th	Night	13% 8% 2 7% 5% 5% 5% 5% 7% 8% 34%	2070
	21st to end	Night	16% 6% 3 7% 4 3 4 4 5% 8% 39%	2114
October	1st to 10th	Night	14% 6% 2 5% 4 4 4 3 5% 6% 46%	2280
	11th to 20th	Night	9% 4 2 5% 4 4 3 3 5% 6% 56%	2280
	21st to end	Night	9% 4 2 5% 3 4 4 2 4 6% 57%	2508
November	1st to 10th	Night	11% 5% 2 5% 4 4 3 3 5% 6% 53%	2341
	11th to 20th	Night	13% 7% 2 6% 4 3 3 3 5% 5% 48%	2287
	21st to end	Night	10% 5% 2 6% 4 4 4 3 7% 8% 47%	2384
December	1st to 10th	Night	15% 7% 2 6% 4 5% 5% 4 6% 7% 40%	2470
	11th to 20th	Night	16% 6% 2 5% 4 3 2 2 5% 5% 49%	3042
	21st to end	Night	16% 7% 2 6% 4 3 4 4 6% 7% 41%	4532

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	34% 6% 8% 21% 25% 6%	2837
	11th to 20th	Day	35% 4 7% 20% 25% 9%	2840
	21st to end	Day	42% 5% 7% 20% 18% 8%	3124
February	1st to 10th	Day	42% 6% 9% 20% 19% 4	1710
	11th to 20th	Day	41% 6% 7% 17% 22% 7%	1772
	21st to end	Day	41% 6% 9% 18% 17% 9%	1727
March	1st to 10th	Day	48% 6% 10% 15% 15% 6%	3435
	11th to 20th	Day	29% 7% 11% 17% 26% 10%	3480
	21st to end	Day	38% 7% 10% 19% 20% 6%	3815
April	1st to 10th	Day	30% 6% 13% 20% 24% 6%	2175
	11th to 20th	Day	30% 6% 12% 24% 18% 10%	2254
	21st to end	Day	26% 7% 14% 27% 22% 4	2280
May	1st to 10th	Day	31% 12% 19% 26% 11% 2	3948
	11th to 20th	Day	41% 7% 16% 25% 11%	4085
	21st to end	Day	25% 10% 21% 27% 16%	4489
June	1st to 10th	Day	40% 12% 18% 21% 10%	2470
	11th to 20th	Day	31% 12% 22% 24% 11%	2470
	21st to end	Day	35% 14% 23% 22% 7% 1	2470
July	1st to 10th	Day	42% 13% 22% 20% 4 1	4055
	11th to 20th	Day	41% 15% 29% 11% 4	4051
	21st to end	Day	44% 14% 22% 15% 5%	4324
August	1st to 10th	Day	53% 10% 24% 11% 2	4091
	11th to 20th	Day	36% 12% 22% 21% 9%	3874
	21st to end	Day	35% 10% 18% 32% 5%	4180
September	1st to 10th	Day	34% 12% 21% 17% 14% 3	2280
	11th to 20th	Day	42% 10% 14% 16% 13% 4	2104
	21st to end	Day	42% 7% 13% 20% 15% 3	2066
October	1st to 10th	Day	40% 4 9% 17% 25% 5%	3160
	11th to 20th	Day	19% 4 6% 16% 30% 26%	3140
	21st to end	Day	28% 5% 7% 19% 33% 8%	3428
November	1st to 10th	Day	32% 5% 10% 17% 27% 9%	1957
	11th to 20th	Day	38% 4 8% 17% 23% 9%	1900
	21st to end	Day	35% 4 10% 21% 23% 7%	1791
December	1st to 10th	Day	42% 8% 13% 18% 13% 6%	1710
	11th to 20th	Day	32% 4 8% 24% 25% 7%	2150
	21st to end	Day	43% 6% 8% 18% 21% 4	3124
January	1st to 10th	Night	38% 6% 8% 19% 21% 8%	4109
	11th to 20th	Night	40% 6% 8% 18% 24% 5%	4120
	21st to end	Night	42% 5% 7% 13% 27% 6%	4532
February	1st to 10th	Night	40% 4 10% 19% 19% 8%	2470
	11th to 20th	Night	44% 5% 8% 16% 19% 9%	2301
	21st to end	Night	41% 6% 10% 18% 16% 10%	1727
March	1st to 10th	Night	53% 5% 10% 13% 12% 6%	3418
	11th to 20th	Night	33% 6% 9% 17% 23% 12%	3480
	21st to end	Night	37% 6% 10% 23% 17% 6%	3817
April	1st to 10th	Night	35% 4 12% 19% 21% 9%	2004
	11th to 20th	Night	33% 5% 11% 21% 19% 10%	1875
	21st to end	Night	28% 7% 15% 24% 20% 5%	1900
May	1st to 10th	Night	29% 10% 19% 26% 13% 3	3040
	11th to 20th	Night	38% 10% 15% 23% 14%	2813
	21st to end	Night	27% 11% 17% 27% 17% 1	3087
June	1st to 10th	Night	37% 12% 19% 22% 9% 1	1710
	11th to 20th	Night	34% 9% 22% 25% 10%	1710
	21st to end	Night	34% 14% 23% 22% 7%	1710
July	1st to 10th	Night	43% 13% 19% 20% 5%	2795
	11th to 20th	Night	42% 13% 32% 9% 3	2786
	21st to end	Night	39% 17% 22% 19% 3	2988
August	1st to 10th	Night	50% 11% 24% 13% 2	2814
	11th to 20th	Night	33% 12% 24% 25% 6%	2988
	21st to end	Night	32% 10% 18% 35% 5%	3476
September	1st to 10th	Night	39% 12% 16% 17% 13% 3	1900
	11th to 20th	Night	44% 11% 14% 16% 14% 2	2070
	21st to end	Night	43% 7% 13% 21% 13% 3	2114
October	1st to 10th	Night	36% 6% 8% 19% 25% 6%	3800
	11th to 20th	Night	19% 3 6% 14% 24% 34%	3779
	21st to end	Night	25% 4 6% 22% 28% 14%	4120
November	1st to 10th	Night	32% 5% 10% 17% 25% 11%	2341
	11th to 20th	Night	38% 4 9% 15% 22% 11%	2287
	21st to end	Night	34% 5% 11% 21% 21% 8%	2384
December	1st to 10th	Night	42% 7% 13% 15% 17% 6%	2470
	11th to 20th	Night	38% 3 8% 20% 25% 7%	3044
	21st to end	Night	41% 5% 8% 22% 20% 4	4532

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	11% 8% 27% 42% 11%	270
	11th to 20th	Day	8% 4 24% 47% 15% 2	270
	21st to end	Day	20% 4 28% 37% 10% 1	297
February	1st to 10th	Day	14% 4 26% 40% 14% 1	270
	11th to 20th	Day	23% 4 27% 33% 12%	314
	21st to end	Day	15% 7% 28% 38% 11% 1	382
March	1st to 10th	Day	15% 5% 27% 33% 19% 1	460
	11th to 20th	Day	14% 5% 25% 37% 16% 2	460
	21st to end	Day	13% 4 25% 38% 19% 2	506
April	1st to 10th	Day	11% 6% 22% 38% 20% 3	460
	11th to 20th	Day	8% 3 20% 30% 31% 8%	452
	21st to end	Day	8% 5% 15% 32% 28% 11%	460
May	1st to 10th	Day	4 3 20% 37% 24% 11%	463
	11th to 20th	Day	11% 2 14% 27% 35% 12%	487
	21st to end	Day	12% 1 7% 25% 35% 21%	529
June	1st to 10th	Day	8% 1 8% 24% 44% 14%	490
	11th to 20th	Day	11% 1 7% 22% 37% 22%	490
	21st to end	Day	7% 1 4 21% 47% 20%	490
July	1st to 10th	Day	9% 1 6% 12% 44% 28%	485
	11th to 20th	Day	7% 2 3 11% 45% 31%	484
	21st to end	Day	6% 2 3 18% 47% 24%	532
August	1st to 10th	Day	15% 2 6% 15% 40% 23%	486
	11th to 20th	Day	11% 1 4 15% 39% 31%	479
	21st to end	Day	14% 1 7% 14% 36% 28%	539
September	1st to 10th	Day	11% 2 4 20% 39% 24%	490
	11th to 20th	Day	17% 2 9% 20% 36% 16%	490
	21st to end	Day	16% 2 8% 20% 37% 17%	490
October	1st to 10th	Day	17% 2 12% 27% 27% 14%	490
	11th to 20th	Day	9% 2 16% 28% 30% 15%	490
	21st to end	Day	10% 2 16% 29% 32% 12%	539
November	1st to 10th	Day	16% 5% 16% 27% 27% 10%	495
	11th to 20th	Day	15% 6% 21% 37% 18% 4	460
	21st to end	Day	12% 4 21% 36% 23% 4	351
December	1st to 10th	Day	20% 2 16% 39% 21% 1	270
	11th to 20th	Day	16% 4 25% 34% 17% 4	270
	21st to end	Day	15% 6% 23% 34% 17% 4	297
January	1st to 10th	Night	15% 11% 30% 33% 10% 1	760
	11th to 20th	Night	13% 8% 29% 34% 14% 1	760
	21st to end	Night	16% 8% 36% 35% 5%	836
February	1st to 10th	Night	17% 6% 29% 38% 10%	760
	11th to 20th	Night	20% 9% 30% 36% 5%	743
	21st to end	Night	17% 5% 29% 36% 12%	628
March	1st to 10th	Night	16% 5% 29% 37% 14%	760
	11th to 20th	Night	13% 6% 26% 39% 14% 2	760
	21st to end	Night	15% 4 28% 36% 17% 1	836
April	1st to 10th	Night	12% 6% 26% 37% 18% 2	760
	11th to 20th	Night	10% 5% 23% 31% 26% 5%	751
	21st to end	Night	8% 3 21% 37% 26% 5%	760
May	1st to 10th	Night	7% 3 21% 37% 27% 5%	692
	11th to 20th	Night	12% 2 15% 34% 31% 6%	561
	21st to end	Night	9% 1 7% 25% 41% 18%	617
June	1st to 10th	Night	11% 2 9% 32% 38% 9%	570
	11th to 20th	Night	9% 1 6% 24% 44% 16%	570
	21st to end	Night	7% 2 6% 28% 43% 14%	570
July	1st to 10th	Night	8% 3 6% 17% 50% 16%	555
	11th to 20th	Night	9% 2 4 18% 52% 16%	552
	21st to end	Night	5% 2 5% 26% 49% 13%	624
August	1st to 10th	Night	10% 4 21% 48% 17%	567
	11th to 20th	Night	9% 2 4 21% 46% 18%	662
	21st to end	Night	11% 1 6% 17% 44% 21%	836
September	1st to 10th	Night	11% 1 5% 21% 48% 13%	760
	11th to 20th	Night	15% 3 8% 26% 37% 11%	760
	21st to end	Night	20% 2 9% 23% 35% 11%	760
October	1st to 10th	Night	16% 3 13% 30% 30% 9%	760
	11th to 20th	Night	11% 3 20% 31% 29% 6%	760
	21st to end	Night	11% 5% 18% 28% 31% 7%	836
November	1st to 10th	Night	13% 3 21% 32% 26% 5%	780
	11th to 20th	Night	15% 6% 24% 34% 18% 3	763
	21st to end	Night	11% 6% 25% 35% 19% 4	760
December	1st to 10th	Night	17% 7% 23% 37% 15% 2	760
	11th to 20th	Night	19% 6% 26% 31% 16% 2	760
	21st to end	Night	19% 7% 26% 34% 14% 1	836

Page generated at 2024-11-08 06:44:51. Version ac07

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