Cachuma Lake Recreation Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cachuma Lake Recreation Area clear sky chart from 2005-11-06 to 2024-11-05.

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 5% 70%	104728
	Night	5% 3 1 3 2 2 3 2 4 5% 69%	103074
Transparency	Day	9% 46% 4 11% 16% 14%	104486
	Night	10% 46% 4 9% 16% 16%	102907
Seeing	Day	8% 11% 26% 34% 17% 4	15632
	Night	6% 6% 19% 34% 29% 7%	25305

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	7% 3 1 4 3 2 3 3 5% 6% 63%	2678
	11th to 20th	Day	10% 5% 2 4 3 4 4 3 6% 9% 52%	2860
	21st to end	Day	12% 5% 1 5% 3 4 5% 4 6% 7% 48%	3146
February	1st to 10th	Day	11% 5% 2 3 3 2 2 2 5% 5% 59%	1869
	11th to 20th	Day	8% 4 1 3 4 3 3 4 5% 8% 57%	1850
	21st to end	Day	10% 5% 2 4 4 3 4 3 5% 6% 55%	1570
March	1st to 10th	Day	13% 6% 2 5% 3 4 4 4 5% 7% 48%	3155
	11th to 20th	Day	5% 3 1 3 3 2 2 2 3 7% 69%	3490
	21st to end	Day	8% 6% 2 5% 4 4 5% 4 6% 8% 48%	4056
April	1st to 10th	Day	6% 4 1 4 3 4 4 3 6% 7% 58%	2280
	11th to 20th	Day	5% 3 1 4 3 3 2 3 4 6% 66%	2249
	21st to end	Day	4 2 1 2 3 3 3 3 5% 6% 68%	2280
May	1st to 10th	Day	3 2 1 2 2 2 2 2 3 5% 77%	3800
	11th to 20th	Day	1 1 1 3 4 2 3 3 5% 8% 70%	3935
	21st to end	Day	2 2 1 3 2 2 2 2 4 6% 75%	4644
June	1st to 10th	Day	3 2 1 3 3 3 2 2 5% 7% 69%	2660
	11th to 20th	Day	1 3 2 1 2 1 2 4 5% 79%	2660
	21st to end	Day	1 1 1 2 2 2 2 2 3 5% 81%	2660
July	1st to 10th	Day	1 1 1 1 2 1 2 4 86%	4420
	11th to 20th	Day	2 2 1 2 2 2 2 2 3 4 78%	4172
	21st to end	Day	1 1 1 1 2 2 1 2 3 5% 82%	4435
August	1st to 10th	Day	1 1 2 1 2 2 2 3 4 82%	3783
	11th to 20th	Day	1 1 1 1 1 1 2 3 90%	3724
	21st to end	Day	1 1 1 2 1 1 2 3 88%	4180
September	1st to 10th	Day	2 1 1 1 2 2 2 3 6% 79%	2280
	11th to 20th	Day	1 1 3 2 2 1 1 3 4 82%	2238
	21st to end	Day	1 1 1 2 1 2 1 3 4 83%	2090
October	1st to 10th	Day	2 1 1 2 1 2 2 2 4 4 80%	3291
	11th to 20th	Day	2 1 2 2 3 2 2 4 4 79%	3161
	21st to end	Day	2 2 1 3 2 3 3 2 4 5% 73%	3448
November	1st to 10th	Day	4 2 1 3 2 3 3 3 3 5% 71%	1797
	11th to 20th	Day	3 4 1 3 3 3 3 3 4 6% 69%	1710
	21st to end	Day	4 3 2 4 4 3 3 3 5% 7% 63%	1710
December	1st to 10th	Day	8% 5% 2 5% 3 3 3 3 4 6% 59%	1710
	11th to 20th	Day	21% 6% 2 5% 3 3 4 3 4 5% 43%	1943
	21st to end	Day	14% 6% 1 5% 5% 3 3 3 6% 8% 46%	2794
January	1st to 10th	Night	8% 4 1 4 3 3 3 3 4 5% 61%	4255
	11th to 20th	Night	8% 6% 2 6% 3 3 4 3 5% 8% 51%	4110
	21st to end	Night	14% 6% 2 4 3 3 4 3 5% 9% 49%	4521
February	1st to 10th	Night	10% 6% 2 4 3 2 3 2 4 6% 59%	2308
	11th to 20th	Night	7% 4 1 4 3 3 3 3 6% 7% 60%	2218
	21st to end	Night	9% 5% 2 4 4 4 3 3 4 4 58%	1884
March	1st to 10th	Night	11% 6% 2 4 3 3 5% 4 7% 8% 47%	3716
	11th to 20th	Night	4 2 1 3 3 3 3 3 5% 7% 65%	3490
	21st to end	Night	12% 4 2 3 3 3 3 3 5% 6% 57%	3595
April	1st to 10th	Night	6% 5% 1 3 3 3 3 3 5% 6% 63%	1900
	11th to 20th	Night	5% 3 1 3 2 2 2 3 5% 4 71%	1879
	21st to end	Night	2 2 1 3 3 3 2 3 4 7% 71%	1900
May	1st to 10th	Night	2 2 1 2 1 1 2 3 3 82%	3180
	11th to 20th	Night	1 2 1 4 4 2 2 2 3 5% 73%	2972
	21st to end	Night	1 2 1 2 1 1 1 1 2 4 83%	2932
June	1st to 10th	Night	2 1 3 3 3 3 4 5% 8% 67%	1520
	11th to 20th	Night	1 3 2 2 1 2 2 4 5% 79%	1520
	21st to end	Night	1 1 1 2 1 1 1 2 2 4 84%	1520
July	1st to 10th	Night	1 1 1 2 1 2 4 87%	2540
	11th to 20th	Night	1 2 2 2 3 2 3 5% 80%	2790
	21st to end	Night	1 1 2 2 2 1 2 4 85%	3126
August	1st to 10th	Night	1 1 2 2 1 2 1 2 5% 84%	3166
	11th to 20th	Night	1 1 1 1 1 3 3 89%	3126
	21st to end	Night	1 1 1 1 1 1 2 93%	3498
September	1st to 10th	Night	1 1 2 2 2 2 2 2 3 82%	1900
	11th to 20th	Night	1 2 1 2 1 1 2 1 3 3 83%	1940
	21st to end	Night	1 1 1 1 1 2 3 4 84%	2090
October	1st to 10th	Night	2 1 1 1 1 1 1 2 2 3 85%	3672
	11th to 20th	Night	1 1 1 2 2 2 2 3 3 5% 78%	3777
	21st to end	Night	2 2 1 2 2 1 2 1 3 5% 79%	4121
November	1st to 10th	Night	3 3 1 3 2 2 3 2 4 6% 71%	2379
	11th to 20th	Night	3 3 1 4 2 2 3 3 4 6% 69%	2470
	21st to end	Night	5% 3 1 3 3 4 4 3 5% 6% 63%	2470
December	1st to 10th	Night	7% 4 1 4 3 3 3 3 5% 6% 60%	2470
	11th to 20th	Night	20% 6% 2 4 4 2 4 3 6% 7% 42%	3257
	21st to end	Night	12% 7% 2 6% 4 4 4 3 5% 6% 45%	4862

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	11% 37% 5% 25% 19% 3	2678
	11th to 20th	Day	21% 41% 10% 13% 13% 2	2860
	21st to end	Day	21% 41% 5% 18% 11% 3	3146
February	1st to 10th	Day	13% 65% 3 7% 7% 6%	1869
	11th to 20th	Day	9% 64% 3 6% 11% 8%	1860
	21st to end	Day	9% 65% 3 7% 11% 4	1570
March	1st to 10th	Day	22% 42% 6% 17% 10% 3	3155
	11th to 20th	Day	6% 39% 10% 25% 11% 10%	3490
	21st to end	Day	20% 43% 9% 18% 8% 1	4056
April	1st to 10th	Day	9% 66% 4 8% 9% 4	2280
	11th to 20th	Day	6% 66% 2 8% 13% 4	2252
	21st to end	Day	6% 65% 4 10% 12% 3	2280
May	1st to 10th	Day	8% 40% 5% 12% 25% 11%	3800
	11th to 20th	Day	4 47% 8% 16% 21% 3	3938
	21st to end	Day	4 42% 6% 27% 19% 2	4644
June	1st to 10th	Day	5% 66% 2 10% 12% 4	2660
	11th to 20th	Day	5% 64% 1 8% 14% 8%	2660
	21st to end	Day	6% 62% 2 5% 13% 12%	2660
July	1st to 10th	Day	4 34% 1 4 7% 49%	4351
	11th to 20th	Day	9% 35% 3 5% 11% 37%	4101
	21st to end	Day	4 34% 2 10% 21% 29%	4295
August	1st to 10th	Day	5% 35% 2 8% 29% 21%	3770
	11th to 20th	Day	2 36% 1 3 23% 35%	3760
	21st to end	Day	3 35% 1 7% 22% 31%	4179
September	1st to 10th	Day	6% 60% 2 4 15% 13%	2280
	11th to 20th	Day	6% 60% 1 8% 17% 9%	2238
	21st to end	Day	3 59% 2 7% 18% 11%	2090
October	1st to 10th	Day	4 35% 1 5% 13% 41%	3291
	11th to 20th	Day	5% 37% 3 14% 26% 14%	3161
	21st to end	Day	11% 35% 2 4 29% 19%	3448
November	1st to 10th	Day	4 57% 2 8% 15% 15%	1797
	11th to 20th	Day	10% 60% 3 8% 7% 12%	1710
	21st to end	Day	9% 60% 4 8% 9% 10%	1710
December	1st to 10th	Day	13% 60% 2 8% 9% 7%	1710
	11th to 20th	Day	26% 49% 3 5% 9% 8%	1943
	21st to end	Day	23% 39% 6% 16% 10% 5%	2794
January	1st to 10th	Night	16% 38% 3 16% 20% 7%	4255
	11th to 20th	Night	23% 41% 6% 13% 14% 3	4110
	21st to end	Night	20% 43% 5% 13% 15% 4	4521
February	1st to 10th	Night	12% 65% 3 5% 7% 7%	2308
	11th to 20th	Night	8% 64% 2 5% 13% 8%	2219
	21st to end	Night	9% 64% 2 7% 12% 5%	1884
March	1st to 10th	Night	20% 43% 5% 15% 14% 4	3716
	11th to 20th	Night	8% 41% 7% 21% 14% 10%	3490
	21st to end	Night	17% 42% 11% 16% 12% 2	3595
April	1st to 10th	Night	9% 65% 4 10% 8% 4	1900
	11th to 20th	Night	6% 66% 4 6% 13% 5%	1879
	21st to end	Night	4 65% 5% 11% 11% 4	1900
May	1st to 10th	Night	4 40% 4 13% 23% 16%	3180
	11th to 20th	Night	6% 42% 9% 10% 21% 12%	2973
	21st to end	Night	3 43% 6% 18% 27% 4	2932
June	1st to 10th	Night	7% 66% 3 7% 11% 6%	1520
	11th to 20th	Night	4 64% 1 3 15% 12%	1520
	21st to end	Night	7% 62% 2 4 11% 15%	1520
July	1st to 10th	Night	3 34% 1 3 8% 51%	2500
	11th to 20th	Night	6% 34% 5% 4 10% 40%	2739
	21st to end	Night	3 34% 1 6% 20% 35%	3028
August	1st to 10th	Night	5% 35% 1 8% 25% 26%	3156
	11th to 20th	Night	2 35% 1 2 16% 43%	3156
	21st to end	Night	2 35% 1 5% 19% 39%	3498
September	1st to 10th	Night	6% 59% 2 3 13% 17%	1900
	11th to 20th	Night	5% 59% 2 5% 16% 12%	1940
	21st to end	Night	3 59% 2 4 19% 13%	2090
October	1st to 10th	Night	2 35% 1 4 14% 44%	3672
	11th to 20th	Night	4 36% 3 11% 24% 21%	3777
	21st to end	Night	7% 35% 2 5% 29% 22%	4121
November	1st to 10th	Night	4 56% 2 7% 16% 16%	2379
	11th to 20th	Night	9% 60% 3 6% 9% 14%	2470
	21st to end	Night	10% 60% 4 9% 8% 9%	2470
December	1st to 10th	Night	10% 60% 3 9% 11% 7%	2470
	11th to 20th	Night	24% 50% 3 6% 9% 9%	3257
	21st to end	Night	27% 40% 5% 13% 11% 5%	4862

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	19% 13% 31% 23% 12% 1	267
	11th to 20th	Day	17% 16% 25% 28% 13% 2	370
	21st to end	Day	13% 14% 35% 25% 10% 2	407
February	1st to 10th	Day	15% 15% 25% 25% 15% 4	446
	11th to 20th	Day	17% 17% 29% 26% 9% 2	455
	21st to end	Day	14% 18% 32% 25% 8% 2	382
March	1st to 10th	Day	20% 20% 32% 21% 6% 1	460
	11th to 20th	Day	14% 21% 32% 25% 7% 1	460
	21st to end	Day	17% 22% 33% 22% 6%	506
April	1st to 10th	Day	12% 18% 32% 24% 12% 2	460
	11th to 20th	Day	11% 20% 36% 24% 7% 2	452
	21st to end	Day	8% 18% 34% 26% 12% 3	460
May	1st to 10th	Day	11% 16% 33% 27% 10% 3	463
	11th to 20th	Day	5% 14% 34% 31% 14% 2	488
	21st to end	Day	9% 13% 32% 33% 11% 3	529
June	1st to 10th	Day	5% 8% 27% 37% 21% 2	490
	11th to 20th	Day	4 7% 29% 37% 18% 6%	490
	21st to end	Day	2 4 22% 44% 23% 5%	490
July	1st to 10th	Day	1 1 17% 48% 27% 6%	486
	11th to 20th	Day	2 1 11% 45% 31% 10%	484
	21st to end	Day	2 1 12% 46% 28% 11%	531
August	1st to 10th	Day	2 2 21% 46% 24% 5%	487
	11th to 20th	Day	2 1 14% 45% 31% 6%	477
	21st to end	Day	1 2 14% 49% 28% 5%	539
September	1st to 10th	Day	3 3 20% 47% 22% 6%	490
	11th to 20th	Day	3 6% 30% 43% 14% 3	490
	21st to end	Day	1 7% 24% 42% 22% 4	490
October	1st to 10th	Day	4 10% 24% 38% 23% 2	490
	11th to 20th	Day	4 8% 29% 38% 18% 4	490
	21st to end	Day	6% 9% 27% 35% 20% 4	539
November	1st to 10th	Day	7% 10% 25% 34% 20% 4	369
	11th to 20th	Day	7% 9% 24% 40% 17% 4	270
	21st to end	Day	7% 10% 24% 35% 20% 4	270
December	1st to 10th	Day	11% 11% 30% 30% 16% 2	270
	11th to 20th	Day	12% 15% 24% 28% 16% 6%	187
	21st to end	Day	21% 15% 31% 21% 10% 3	198
January	1st to 10th	Night	12% 8% 24% 29% 17% 10%	760
	11th to 20th	Night	8% 6% 24% 33% 20% 8%	760
	21st to end	Night	11% 9% 27% 32% 16% 5%	836
February	1st to 10th	Night	13% 6% 23% 31% 22% 5%	760
	11th to 20th	Night	9% 11% 25% 31% 17% 7%	744
	21st to end	Night	11% 11% 27% 32% 17% 3	628
March	1st to 10th	Night	12% 11% 25% 36% 15% 3	760
	11th to 20th	Night	9% 9% 24% 34% 21% 3	760
	21st to end	Night	10% 11% 28% 33% 16% 3	836
April	1st to 10th	Night	8% 8% 30% 33% 18% 2	760
	11th to 20th	Night	6% 11% 27% 33% 19% 4	751
	21st to end	Night	3 10% 29% 31% 21% 6%	760
May	1st to 10th	Night	5% 8% 22% 35% 26% 4	760
	11th to 20th	Night	4 6% 21% 37% 29% 4	647
	21st to end	Night	3 8% 27% 33% 27% 2	517
June	1st to 10th	Night	1 5% 15% 38% 39% 2	380
	11th to 20th	Night	2 2 14% 39% 38% 6%	380
	21st to end	Night	1 1 11% 35% 47% 5%	380
July	1st to 10th	Night	8% 28% 53% 10%	370
	11th to 20th	Night	1 2 22% 58% 16%	511
	21st to end	Night	1 3 23% 55% 18%	629
August	1st to 10th	Night	2 8% 35% 46% 9%	756
	11th to 20th	Night	1 5% 29% 54% 11%	752
	21st to end	Night	1 1 5% 30% 51% 12%	836
September	1st to 10th	Night	2 2 8% 33% 46% 10%	760
	11th to 20th	Night	2 3 13% 40% 33% 8%	760
	21st to end	Night	1 2 12% 38% 39% 8%	760
October	1st to 10th	Night	3 3 14% 41% 34% 4	760
	11th to 20th	Night	4 4 17% 40% 29% 7%	760
	21st to end	Night	3 4 20% 35% 29% 9%	836
November	1st to 10th	Night	5% 5% 20% 36% 25% 9%	760
	11th to 20th	Night	6% 4 18% 39% 27% 6%	760
	21st to end	Night	6% 5% 22% 38% 21% 7%	760
December	1st to 10th	Night	9% 6% 20% 34% 24% 7%	760
	11th to 20th	Night	12% 7% 24% 35% 18% 4	760
	21st to end	Night	11% 12% 23% 34% 16% 5%	836

Page generated at 2024-11-02 23:11:21. Version ac07

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