Santa Paula
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Santa Paula clear sky chart from 2005-11-06 to 2026-07-31.

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	4 3 1 3 2 2 3 2 4 6% 69%	146178
	Night	5% 3 1 3 2 2 3 2 4 6% 69%	144393
Transparency	Day	17% 4 7% 19% 28% 25%	141262
	Night	17% 4 7% 19% 27% 24%	140284
Seeing	Day	7% 9% 29% 36% 15% 5%	17931
	Night	6% 3 15% 34% 33% 9%	27652

By Month

Percentage Cloud Cover SW (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	10% 3 1 3 2 2 2 2 3 4 67%	4800
	11th to 20th	Day	5% 2 1 2 1 2 2 2 4 6% 74%	5340
	21st to end	Day	7% 4 1 4 3 3 4 3 5% 8% 57%	6100
February	1st to 10th	Day	10% 5% 2 4 2 2 2 3 5% 5% 60%	2100
	11th to 20th	Day	8% 4 1 3 3 3 3 3 5% 7% 60%	2050
	21st to end	Day	8% 3 1 5% 2 3 3 3 4 7% 61%	1730
March	1st to 10th	Day	11% 5% 2 4 3 3 3 3 5% 6% 56%	4618
	11th to 20th	Day	8% 4 2 4 3 3 3 3 4 7% 60%	4929
	21st to end	Day	7% 5% 2 6% 4 4 5% 4 6% 9% 49%	6050
April	1st to 10th	Day	5% 4 1 3 3 3 3 3 5% 8% 62%	2520
	11th to 20th	Day	4 4 2 4 2 2 3 3 4 8% 64%	2489
	21st to end	Day	4 5% 1 3 2 3 3 2 4 7% 66%	2520
May	1st to 10th	Day	4 4 1 3 3 3 3 2 4 6% 66%	7058
	11th to 20th	Day	3 5% 1 4 3 3 3 3 5% 8% 63%	7570
	21st to end	Day	2 5% 2 4 3 3 3 3 4 7% 64%	8370
June	1st to 10th	Day	4 6% 1 4 3 3 3 3 5% 7% 61%	2909
	11th to 20th	Day	3 3 1 3 2 2 3 3 3 7% 70%	2940
	21st to end	Day	1 2 1 2 2 2 2 2 4 5% 78%	2940
July	1st to 10th	Day	1 1 1 1 1 2 3 4 85%	6459
	11th to 20th	Day	1 1 1 2 2 2 3 2 4 5% 78%	6295
	21st to end	Day	1 2 1 2 1 1 2 2 3 5% 82%	6272
August	1st to 10th	Day	1 1 1 2 1 1 2 2 4 5% 82%	5346
	11th to 20th	Day	1 1 1 1 1 1 1 2 4 88%	5364
	21st to end	Day	1 1 1 1 1 1 2 3 88%	5984
September	1st to 10th	Day	1 1 1 2 2 2 2 2 3 4 80%	2400
	11th to 20th	Day	2 2 1 2 2 2 2 2 3 5% 77%	2305
	21st to end	Day	2 2 1 2 2 2 2 2 3 5% 78%	2200
October	1st to 10th	Day	2 1 1 1 1 2 2 3 4 83%	3551
	11th to 20th	Day	3 4 1 4 3 2 3 2 4 6% 69%	3261
	21st to end	Day	2 3 1 3 2 3 4 2 4 5% 71%	3558
November	1st to 10th	Day	2 2 1 2 3 2 2 2 4 7% 74%	1879
	11th to 20th	Day	6% 3 1 3 2 2 2 3 4 5% 68%	1890
	21st to end	Day	4 3 1 3 3 3 3 3 4 7% 65%	1890
December	1st to 10th	Day	4 2 1 3 2 3 4 3 5% 7% 66%	3040
	11th to 20th	Day	11% 4 2 4 3 3 4 3 5% 7% 55%	3359
	21st to end	Day	9% 4 1 5% 4 4 3 3 6% 9% 52%	4092
January	1st to 10th	Night	10% 4 1 4 2 3 3 2 3 4 63%	8081
	11th to 20th	Night	4 3 1 3 2 2 2 2 4 6% 72%	7650
	21st to end	Night	8% 6% 2 4 3 3 4 3 5% 5% 56%	8112
February	1st to 10th	Night	9% 5% 1 4 2 2 3 2 4 5% 63%	2520
	11th to 20th	Night	9% 3 1 4 2 2 3 3 4 6% 63%	2458
	21st to end	Night	9% 4 1 3 3 2 3 3 4 5% 61%	2076
March	1st to 10th	Night	8% 6% 2 4 3 3 3 3 5% 7% 56%	5496
	11th to 20th	Night	6% 4 1 4 3 3 3 3 5% 6% 62%	5274
	21st to end	Night	10% 6% 2 4 3 2 3 3 4 6% 58%	5166
April	1st to 10th	Night	5% 4 2 2 3 3 3 2 4 7% 63%	2100
	11th to 20th	Night	4 4 1 3 2 2 2 3 5% 5% 68%	2079
	21st to end	Night	3 5% 1 2 2 2 2 2 4 7% 69%	2100
May	1st to 10th	Night	3 4 1 4 2 4 3 2 4 5% 69%	5919
	11th to 20th	Night	1 3 1 2 3 4 3 2 3 5% 74%	5319
	21st to end	Night	1 2 1 2 2 2 2 3 3 5% 77%	5837
June	1st to 10th	Night	1 4 1 3 2 3 2 3 4 7% 69%	1705
	11th to 20th	Night	1 2 1 2 2 2 3 2 4 6% 76%	1680
	21st to end	Night	1 1 1 1 1 1 2 3 4 5% 80%	1680
July	1st to 10th	Night	1 1 1 1 2 2 3 4 85%	3720
	11th to 20th	Night	1 1 1 1 1 3 4 5% 5% 77%	3861
	21st to end	Night	1 1 1 1 1 2 2 4 5% 82%	4832
August	1st to 10th	Night	1 1 1 1 1 2 2 3 5% 83%	4486
	11th to 20th	Night	1 1 1 1 1 1 2 3 89%	4506
	21st to end	Night	1 1 1 1 2 2 3 5% 85%	5015
September	1st to 10th	Night	2 2 1 2 1 2 2 2 3 6% 78%	2000
	11th to 20th	Night	3 1 1 2 2 2 3 2 3 4 79%	2093
	21st to end	Night	2 2 1 1 1 1 2 2 4 5% 80%	2200
October	1st to 10th	Night	2 1 1 1 1 1 2 2 3 3 83%	3645
	11th to 20th	Night	2 3 2 3 2 3 3 2 4 7% 68%	3897
	21st to end	Night	2 2 1 3 2 1 2 1 3 4 79%	4253
November	1st to 10th	Night	3 2 1 3 2 3 2 2 4 6% 73%	2638
	11th to 20th	Night	5% 3 1 3 2 2 2 2 4 5% 71%	2730
	21st to end	Night	6% 3 1 4 3 3 4 3 4 6% 64%	2730
December	1st to 10th	Night	4 2 1 3 3 2 3 3 4 6% 69%	4370
	11th to 20th	Night	13% 4 1 3 2 3 3 4 6% 7% 54%	5059
	21st to end	Night	9% 4 1 4 4 4 5% 4 7% 10% 48%	7106

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	22% 3 7% 19% 28% 22%	4801
	11th to 20th	Day	14% 4 8% 13% 18% 42%	5340
	21st to end	Day	25% 4 6% 16% 24% 25%	6100
February	1st to 10th	Day	26% 4 5% 16% 24% 25%	2100
	11th to 20th	Day	24% 4 8% 19% 26% 20%	2060
	21st to end	Day	24% 4 9% 21% 25% 18%	1730
March	1st to 10th	Day	29% 4 10% 19% 21% 18%	4618
	11th to 20th	Day	23% 5% 11% 29% 19% 13%	4929
	21st to end	Day	27% 7% 15% 26% 19% 5%	6050
April	1st to 10th	Day	21% 6% 12% 25% 25% 11%	2520
	11th to 20th	Day	19% 5% 9% 26% 28% 13%	2492
	21st to end	Day	19% 4 9% 27% 31% 9%	2520
May	1st to 10th	Day	16% 6% 9% 21% 34% 13%	7058
	11th to 20th	Day	19% 6% 8% 26% 29% 12%	7573
	21st to end	Day	17% 7% 11% 31% 28% 7%	8371
June	1st to 10th	Day	23% 6% 11% 20% 30% 10%	2909
	11th to 20th	Day	17% 4 8% 15% 34% 21%	2940
	21st to end	Day	12% 3 5% 10% 35% 34%	2940
July	1st to 10th	Day	6% 2 4 11% 20% 57%	6391
	11th to 20th	Day	8% 5% 6% 14% 36% 33%	6220
	21st to end	Day	9% 2 4 21% 37% 26%	6095
August	1st to 10th	Day	9% 2 3 15% 43% 28%	3890
	11th to 20th	Day	5% 1 3 9% 36% 46%	3880
	21st to end	Day	6% 1 3 10% 36% 43%	4311
September	1st to 10th	Day	10% 2 5% 9% 32% 41%	2400
	11th to 20th	Day	12% 2 6% 14% 31% 34%	2305
	21st to end	Day	12% 3 5% 15% 33% 32%	2200
October	1st to 10th	Day	8% 2 5% 14% 22% 50%	3551
	11th to 20th	Day	19% 3 4 13% 35% 26%	3261
	21st to end	Day	16% 3 3 10% 34% 32%	3558
November	1st to 10th	Day	15% 4 5% 16% 28% 32%	1879
	11th to 20th	Day	19% 3 6% 14% 22% 36%	1890
	21st to end	Day	20% 3 8% 15% 22% 31%	1890
December	1st to 10th	Day	19% 3 4 14% 28% 31%	3040
	11th to 20th	Day	29% 3 7% 18% 26% 17%	3358
	21st to end	Day	29% 6% 11% 26% 19% 9%	4092
January	1st to 10th	Night	25% 5% 5% 15% 29% 21%	8081
	11th to 20th	Night	16% 4 5% 15% 18% 43%	7650
	21st to end	Night	27% 4 5% 14% 24% 25%	8112
February	1st to 10th	Night	26% 4 5% 14% 24% 28%	2520
	11th to 20th	Night	25% 4 5% 21% 23% 23%	2459
	21st to end	Night	26% 4 7% 17% 24% 22%	2076
March	1st to 10th	Night	25% 6% 9% 19% 28% 13%	5496
	11th to 20th	Night	23% 6% 11% 28% 17% 15%	5274
	21st to end	Night	28% 6% 11% 29% 21% 6%	5166
April	1st to 10th	Night	23% 4 12% 25% 24% 13%	2100
	11th to 20th	Night	19% 4 9% 24% 28% 15%	2079
	21st to end	Night	17% 4 10% 26% 32% 11%	2100
May	1st to 10th	Night	16% 9% 11% 22% 32% 11%	5917
	11th to 20th	Night	11% 7% 11% 29% 30% 12%	5320
	21st to end	Night	8% 6% 10% 40% 31% 5%	5838
June	1st to 10th	Night	18% 5% 14% 24% 28% 11%	1705
	11th to 20th	Night	11% 6% 9% 20% 35% 19%	1680
	21st to end	Night	11% 4 5% 14% 33% 34%	1680
July	1st to 10th	Night	5% 3 5% 15% 17% 55%	3680
	11th to 20th	Night	8% 7% 6% 19% 33% 28%	3813
	21st to end	Night	7% 4 7% 26% 34% 22%	4697
August	1st to 10th	Night	8% 2 5% 20% 37% 28%	3256
	11th to 20th	Night	6% 2 5% 10% 39% 39%	3256
	21st to end	Night	6% 2 5% 15% 39% 34%	3608
September	1st to 10th	Night	12% 2 6% 9% 29% 42%	2000
	11th to 20th	Night	12% 4 6% 12% 34% 33%	2093
	21st to end	Night	10% 5% 6% 13% 33% 34%	2200
October	1st to 10th	Night	8% 2 5% 12% 24% 48%	3645
	11th to 20th	Night	15% 5% 8% 17% 27% 28%	3897
	21st to end	Night	12% 2 3 9% 33% 40%	4253
November	1st to 10th	Night	15% 2 7% 15% 27% 34%	2638
	11th to 20th	Night	18% 3 6% 13% 23% 37%	2730
	21st to end	Night	21% 3 6% 17% 20% 33%	2730
December	1st to 10th	Night	18% 3 5% 14% 25% 35%	4370
	11th to 20th	Night	29% 4 8% 15% 22% 22%	5059
	21st to end	Night	30% 6% 12% 28% 17% 8%	7106

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	15% 12% 35% 28% 8% 1	246
	11th to 20th	Day	10% 14% 38% 29% 8%	430
	21st to end	Day	13% 13% 38% 27% 7% 1	520
February	1st to 10th	Day	12% 13% 38% 28% 6% 2	540
	11th to 20th	Day	12% 16% 38% 29% 4 1	535
	21st to end	Day	11% 17% 36% 28% 7%	446
March	1st to 10th	Day	15% 18% 38% 22% 6%	540
	11th to 20th	Day	13% 12% 39% 24% 10% 2	540
	21st to end	Day	12% 15% 36% 27% 9% 1	594
April	1st to 10th	Day	9% 12% 36% 28% 11% 4	540
	11th to 20th	Day	8% 14% 37% 27% 10% 4	532
	21st to end	Day	7% 12% 32% 31% 13% 4	540
May	1st to 10th	Day	9% 12% 31% 33% 9% 6%	543
	11th to 20th	Day	5% 12% 29% 35% 15% 4	568
	21st to end	Day	8% 11% 29% 35% 13% 4	617
June	1st to 10th	Day	6% 8% 22% 39% 19% 6%	570
	11th to 20th	Day	5% 6% 24% 41% 18% 7%	570
	21st to end	Day	2 5% 22% 41% 19% 10%	570
July	1st to 10th	Day	2 2 17% 45% 24% 11%	566
	11th to 20th	Day	2 1 9% 46% 28% 13%	564
	21st to end	Day	1 1 10% 48% 24% 16%	616
August	1st to 10th	Day	1 2 16% 48% 20% 13%	527
	11th to 20th	Day	2 1 11% 50% 22% 14%	517
	21st to end	Day	2 2 15% 47% 23% 10%	583
September	1st to 10th	Day	2 2 22% 45% 20% 9%	530
	11th to 20th	Day	3 6% 29% 43% 14% 4	530
	21st to end	Day	2 6% 26% 41% 19% 5%	530
October	1st to 10th	Day	2 7% 32% 41% 17% 2	530
	11th to 20th	Day	4 6% 34% 39% 14% 3	530
	21st to end	Day	3 7% 35% 33% 17% 4	583
November	1st to 10th	Day	5% 5% 30% 36% 20% 4	355
	11th to 20th	Day	8% 10% 33% 35% 11% 2	330
	21st to end	Day	8% 12% 33% 33% 13% 2	330
December	1st to 10th	Day	9% 8% 34% 33% 14% 2	330
	11th to 20th	Day	6% 11% 31% 32% 18% 3	297
	21st to end	Day	13% 16% 36% 23% 11% 1	242
January	1st to 10th	Night	11% 6% 26% 37% 15% 5%	840
	11th to 20th	Night	7% 6% 29% 40% 16% 3	840
	21st to end	Night	12% 8% 25% 38% 14% 3	924
February	1st to 10th	Night	11% 7% 22% 35% 20% 4	840
	11th to 20th	Night	10% 3 26% 39% 17% 5%	824
	21st to end	Night	10% 6% 21% 42% 19% 2	692
March	1st to 10th	Night	9% 5% 26% 40% 19% 2	840
	11th to 20th	Night	8% 4 17% 40% 25% 6%	840
	21st to end	Night	8% 4 17% 45% 24% 3	924
April	1st to 10th	Night	7% 3 17% 41% 28% 5%	840
	11th to 20th	Night	5% 4 19% 39% 29% 5%	831
	21st to end	Night	4 4 14% 42% 29% 8%	840
May	1st to 10th	Night	6% 3 12% 40% 33% 7%	840
	11th to 20th	Night	4 2 14% 33% 41% 7%	632
	21st to end	Night	2 2 14% 34% 40% 7%	683
June	1st to 10th	Night	3 1 4 30% 51% 12%	445
	11th to 20th	Night	1 4 27% 54% 14%	420
	21st to end	Night	1 3 25% 56% 15%	420
July	1st to 10th	Night	2 13% 63% 21%	410
	11th to 20th	Night	1 1 1 7% 57% 34%	471
	21st to end	Night	1 2 13% 56% 27%	804
August	1st to 10th	Night	1 2 21% 55% 21%	796
	11th to 20th	Night	2 1 1 13% 60% 23%	792
	21st to end	Night	1 1 19% 56% 22%	880
September	1st to 10th	Night	3 1 4 21% 54% 18%	800
	11th to 20th	Night	3 1 4 31% 46% 14%	800
	21st to end	Night	2 1 6% 33% 44% 14%	800
October	1st to 10th	Night	3 1 11% 40% 40% 6%	800
	11th to 20th	Night	3 2 14% 40% 33% 7%	800
	21st to end	Night	3 3 19% 36% 30% 10%	880
November	1st to 10th	Night	4 3 18% 41% 27% 8%	820
	11th to 20th	Night	6% 3 20% 40% 25% 6%	840
	21st to end	Night	7% 4 28% 36% 21% 4	840
December	1st to 10th	Night	7% 7% 25% 37% 20% 5%	840
	11th to 20th	Night	12% 4 25% 38% 18% 3	840
	21st to end	Night	12% 6% 26% 37% 15% 4	924

Page generated at 2026-07-28 00:25:19. Version ac07

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