Choke Canyon State Park - South Shore Unit
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Choke Canyon State Park - South Shore Unit clear sky chart from 2005-11-06 to 2024-11-02.

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	10% 6% 2 6% 4 4 5% 4 6% 8% 45%	100938
	Night	11% 5% 2 5% 3 3 4 3 5% 7% 51%	98135
Transparency	Day	36% 7% 12% 21% 16% 8%	100749
	Night	33% 6% 14% 22% 16% 9%	97995
Seeing	Day	11% 5% 20% 31% 24% 8%	14611
	Night	13% 5% 27% 39% 15% 1	24540

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	15% 7% 2 5% 3 3 3 3 4 4 52%	2847
	11th to 20th	Day	15% 5% 2 4 2 3 3 2 4 6% 54%	2851
	21st to end	Day	20% 8% 3 5% 4 3 5% 4 6% 7% 36%	3487
February	1st to 10th	Day	17% 9% 4 7% 4 3 3 3 4 4 43%	1900
	11th to 20th	Day	18% 7% 2 6% 3 3 3 3 3 6% 45%	1849
	21st to end	Day	15% 6% 2 6% 3 4 4 3 5% 6% 47%	1570
March	1st to 10th	Day	14% 7% 3 8% 5% 5% 5% 4 6% 8% 35%	3419
	11th to 20th	Day	20% 11% 4 8% 5% 4 4 3 4 5% 32%	3480
	21st to end	Day	10% 5% 2 5% 4 3 4 3 5% 7% 51%	3814
April	1st to 10th	Day	11% 7% 2 5% 5% 3 5% 3 7% 7% 45%	2090
	11th to 20th	Day	14% 7% 2 7% 5% 4 3 3 6% 5% 43%	2066
	21st to end	Day	11% 7% 3 6% 5% 4 4 4 5% 6% 46%	2329
May	1st to 10th	Day	12% 7% 3 8% 5% 5% 5% 4 6% 8% 37%	4082
	11th to 20th	Day	9% 7% 3 6% 5% 5% 5% 4 6% 7% 44%	4082
	21st to end	Day	6% 4 2 5% 4 5% 5% 5% 8% 10% 47%	4477
June	1st to 10th	Day	4 2 2 4 5% 4 6% 6% 8% 10% 50%	2470
	11th to 20th	Day	4 4 1 5% 5% 5% 6% 5% 6% 9% 50%	2470
	21st to end	Day	6% 5% 1 6% 7% 7% 7% 6% 8% 10% 37%	2470
July	1st to 10th	Day	6% 4 1 6% 5% 6% 5% 4 7% 9% 46%	4120
	11th to 20th	Day	5% 5% 3 7% 6% 6% 6% 5% 8% 11% 38%	4120
	21st to end	Day	7% 5% 2 6% 6% 6% 6% 6% 7% 10% 38%	4465
August	1st to 10th	Day	1 1 1 2 3 3 4 4 6% 9% 67%	3926
	11th to 20th	Day	2 3 1 3 3 4 6% 4 8% 11% 55%	3726
	21st to end	Day	5% 3 2 6% 5% 5% 6% 6% 8% 13% 40%	3966
September	1st to 10th	Day	8% 6% 3 7% 6% 7% 6% 5% 8% 8% 36%	2090
	11th to 20th	Day	9% 6% 2 8% 5% 6% 5% 4 7% 9% 41%	2090
	21st to end	Day	8% 5% 2 5% 5% 5% 5% 4 6% 8% 47%	2090
October	1st to 10th	Day	5% 4 2 5% 4 4 5% 4 6% 7% 54%	2090
	11th to 20th	Day	11% 4 1 4 3 4 6% 3 6% 7% 51%	1994
	21st to end	Day	9% 4 1 4 3 3 3 2 4 5% 60%	2090
November	1st to 10th	Day	12% 7% 2 6% 4 4 4 3 5% 7% 45%	1868
	11th to 20th	Day	13% 6% 2 6% 4 3 3 3 5% 6% 49%	1834
	21st to end	Day	15% 8% 2 7% 5% 4 4 3 5% 5% 43%	1710
December	1st to 10th	Day	18% 7% 3 6% 4 3 3 3 4 7% 43%	1710
	11th to 20th	Day	18% 9% 3 5% 5% 4 3 3 4 6% 40%	2161
	21st to end	Day	13% 6% 2 6% 4 4 4 3 5% 7% 47%	3135
January	1st to 10th	Night	16% 7% 2 5% 3 2 3 3 5% 6% 48%	4108
	11th to 20th	Night	14% 4 1 4 2 2 2 2 4 6% 59%	4120
	21st to end	Night	22% 7% 2 6% 4 3 3 3 6% 7% 37%	4208
February	1st to 10th	Night	16% 7% 2 5% 4 4 4 3 5% 7% 45%	2280
	11th to 20th	Night	19% 6% 2 4 3 2 3 2 4 6% 49%	2218
	21st to end	Night	15% 6% 2 5% 4 3 3 3 5% 6% 47%	1884
March	1st to 10th	Night	19% 8% 2 7% 4 4 4 3 5% 7% 38%	3433
	11th to 20th	Night	23% 9% 3 8% 5% 4 4 3 4 5% 32%	3480
	21st to end	Night	13% 6% 1 4 3 3 3 3 5% 7% 54%	3817
April	1st to 10th	Night	10% 7% 2 5% 4 3 5% 4 7% 8% 44%	2090
	11th to 20th	Night	14% 6% 2 5% 4 4 4 3 5% 7% 47%	2063
	21st to end	Night	13% 8% 3 6% 4 4 5% 3 5% 7% 42%	1843
May	1st to 10th	Night	15% 8% 2 6% 4 4 4 4 6% 8% 39%	2823
	11th to 20th	Night	12% 6% 2 6% 4 4 4 3 5% 7% 47%	2823
	21st to end	Night	8% 5% 2 6% 3 4 4 4 6% 10% 46%	3090
June	1st to 10th	Night	4 3 1 4 2 3 3 4 7% 9% 61%	1710
	11th to 20th	Night	4 2 4 2 3 4 4 5% 9% 64%	1710
	21st to end	Night	4 4 2 5% 4 3 4 4 7% 10% 53%	1710
July	1st to 10th	Night	4 4 1 4 3 4 4 4 6% 10% 56%	2850
	11th to 20th	Night	4 5% 2 5% 4 4 5% 4 6% 11% 50%	2850
	21st to end	Night	5% 5% 2 5% 5% 4 4 5% 8% 9% 49%	3098
August	1st to 10th	Night	1 1 2 1 1 2 2 3 6% 80%	2995
	11th to 20th	Night	2 2 1 3 3 3 4 3 7% 11% 60%	3113
	21st to end	Night	3 3 1 4 3 3 3 3 6% 11% 59%	3692
September	1st to 10th	Night	5% 6% 2 6% 5% 5% 5% 3 7% 8% 47%	2090
	11th to 20th	Night	8% 5% 3 6% 3 4 4 3 7% 9% 48%	2090
	21st to end	Night	6% 4 2 5% 3 4 3 3 5% 8% 56%	2090
October	1st to 10th	Night	4 3 1 3 2 2 4 3 5% 7% 65%	2090
	11th to 20th	Night	10% 5% 2 4 3 3 3 2 5% 5% 59%	2166
	21st to end	Night	10% 4 1 4 3 2 2 2 4 5% 65%	2508
November	1st to 10th	Night	12% 5% 2 5% 3 4 3 3 5% 6% 52%	2244
	11th to 20th	Night	13% 4 1 5% 3 3 3 3 5% 5% 53%	2341
	21st to end	Night	15% 5% 2 6% 4 3 4 2 6% 7% 47%	2470
December	1st to 10th	Night	17% 7% 2 4 3 3 3 3 4 6% 49%	2470
	11th to 20th	Night	17% 8% 2 5% 4 3 4 3 5% 6% 42%	3036
	21st to end	Night	14% 6% 2 5% 3 3 3 3 5% 8% 47%	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	38% 4 5% 12% 25% 16%	2848
	11th to 20th	Day	33% 3 6% 19% 24% 15%	2851
	21st to end	Day	46% 4 6% 14% 22% 8%	3487
February	1st to 10th	Day	45% 4 6% 10% 20% 15%	1900
	11th to 20th	Day	41% 5% 8% 15% 18% 12%	1859
	21st to end	Day	39% 6% 7% 17% 18% 12%	1570
March	1st to 10th	Day	45% 7% 10% 18% 14% 7%	3419
	11th to 20th	Day	55% 6% 7% 9% 15% 8%	3480
	21st to end	Day	30% 6% 12% 21% 17% 15%	3814
April	1st to 10th	Day	37% 6% 11% 16% 17% 12%	2090
	11th to 20th	Day	42% 5% 9% 17% 14% 13%	2066
	21st to end	Day	38% 6% 7% 19% 18% 12%	2329
May	1st to 10th	Day	42% 8% 13% 19% 11% 7%	4120
	11th to 20th	Day	37% 8% 10% 19% 18% 9%	4086
	21st to end	Day	29% 9% 12% 38% 12% 1	4489
June	1st to 10th	Day	26% 7% 16% 27% 20% 3	2470
	11th to 20th	Day	30% 8% 11% 26% 20% 4	2470
	21st to end	Day	37% 10% 15% 24% 11% 2	2470
July	1st to 10th	Day	33% 8% 20% 33% 6%	4056
	11th to 20th	Day	38% 9% 19% 23% 11% 1	4051
	21st to end	Day	36% 9% 21% 27% 6%	4325
August	1st to 10th	Day	14% 6% 14% 45% 20% 1	3912
	11th to 20th	Day	21% 9% 29% 32% 9% 1	3762
	21st to end	Day	32% 11% 19% 23% 13% 1	3965
September	1st to 10th	Day	43% 11% 14% 14% 14% 4	2090
	11th to 20th	Day	39% 9% 14% 19% 14% 4	2090
	21st to end	Day	33% 7% 13% 18% 17% 11%	2090
October	1st to 10th	Day	29% 7% 10% 18% 25% 10%	2090
	11th to 20th	Day	31% 7% 11% 18% 18% 15%	1994
	21st to end	Day	28% 4 7% 15% 26% 19%	2090
November	1st to 10th	Day	38% 6% 9% 18% 19% 10%	1868
	11th to 20th	Day	37% 4 10% 17% 19% 13%	1834
	21st to end	Day	44% 4 7% 16% 17% 12%	1710
December	1st to 10th	Day	43% 4 8% 17% 19% 9%	1710
	11th to 20th	Day	45% 5% 6% 11% 18% 15%	2159
	21st to end	Day	38% 4 7% 18% 22% 11%	3135
January	1st to 10th	Night	37% 5% 7% 13% 17% 22%	4108
	11th to 20th	Night	28% 3 6% 20% 22% 21%	4120
	21st to end	Night	46% 4 6% 12% 21% 10%	4208
February	1st to 10th	Night	41% 5% 9% 13% 15% 18%	2280
	11th to 20th	Night	38% 4 9% 18% 18% 14%	2218
	21st to end	Night	39% 5% 8% 19% 17% 12%	1884
March	1st to 10th	Night	47% 6% 11% 16% 14% 7%	3433
	11th to 20th	Night	56% 5% 9% 12% 10% 8%	3480
	21st to end	Night	30% 5% 15% 17% 20% 12%	3817
April	1st to 10th	Night	37% 7% 13% 19% 13% 11%	2090
	11th to 20th	Night	39% 6% 11% 16% 13% 16%	2063
	21st to end	Night	42% 6% 10% 18% 15% 9%	1843
May	1st to 10th	Night	43% 8% 13% 18% 12% 7%	2850
	11th to 20th	Night	36% 7% 13% 20% 18% 6%	2824
	21st to end	Night	32% 8% 16% 34% 9% 1	3099
June	1st to 10th	Night	19% 6% 21% 32% 20% 2	1710
	11th to 20th	Night	19% 6% 15% 34% 23% 3	1710
	21st to end	Night	25% 9% 21% 31% 13% 1	1710
July	1st to 10th	Night	24% 8% 27% 36% 5%	2805
	11th to 20th	Night	29% 9% 26% 25% 10%	2796
	21st to end	Night	30% 9% 27% 28% 6%	2999
August	1st to 10th	Night	7% 4 18% 52% 18%	2985
	11th to 20th	Night	19% 7% 36% 34% 5%	3143
	21st to end	Night	19% 10% 29% 32% 10% 1	3692
September	1st to 10th	Night	31% 10% 21% 20% 12% 5%	2090
	11th to 20th	Night	32% 9% 16% 24% 17% 3	2090
	21st to end	Night	25% 6% 15% 27% 18% 9%	2090
October	1st to 10th	Night	18% 7% 14% 28% 21% 12%	2090
	11th to 20th	Night	27% 5% 10% 22% 20% 15%	2166
	21st to end	Night	24% 4 8% 18% 27% 20%	2508
November	1st to 10th	Night	31% 7% 10% 19% 23% 10%	2244
	11th to 20th	Night	33% 5% 13% 18% 19% 13%	2341
	21st to end	Night	38% 5% 10% 19% 17% 11%	2470
December	1st to 10th	Night	39% 5% 9% 18% 19% 11%	2470
	11th to 20th	Night	42% 5% 6% 15% 16% 16%	3037
	21st to end	Night	36% 5% 8% 15% 22% 13%	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	19% 7% 31% 29% 12% 2	270
	11th to 20th	Day	20% 8% 30% 31% 9% 2	270
	21st to end	Day	21% 8% 32% 26% 12% 1	297
February	1st to 10th	Day	20% 10% 30% 26% 12% 2	270
	11th to 20th	Day	20% 10% 36% 23% 10% 1	270
	21st to end	Day	20% 10% 38% 28% 5%	225
March	1st to 10th	Day	20% 10% 38% 25% 7%	270
	11th to 20th	Day	18% 10% 40% 24% 8%	270
	21st to end	Day	13% 11% 39% 31% 4 1	297
April	1st to 10th	Day	17% 10% 35% 29% 10%	270
	11th to 20th	Day	16% 13% 33% 25% 12% 1	264
	21st to end	Day	13% 10% 44% 27% 6% 1	509
May	1st to 10th	Day	13% 12% 38% 28% 8%	653
	11th to 20th	Day	12% 8% 33% 32% 13% 2	675
	21st to end	Day	10% 6% 28% 40% 16% 1	734
June	1st to 10th	Day	5% 2 16% 42% 30% 5%	680
	11th to 20th	Day	5% 1 17% 45% 26% 6%	680
	21st to end	Day	7% 1 11% 36% 32% 13%	680
July	1st to 10th	Day	7% 2 8% 34% 36% 12%	671
	11th to 20th	Day	3 1 6% 35% 44% 11%	668
	21st to end	Day	4 1 5% 34% 44% 12%	739
August	1st to 10th	Day	2 1 4 34% 39% 20%	576
	11th to 20th	Day	4 1 5% 34% 38% 18%	477
	21st to end	Day	6% 1 4 23% 35% 32%	416
September	1st to 10th	Day	10% 1 4 20% 44% 20%	300
	11th to 20th	Day	7% 1 5% 16% 39% 32%	300
	21st to end	Day	9% 1 6% 20% 40% 25%	300
October	1st to 10th	Day	9% 2 9% 23% 38% 20%	300
	11th to 20th	Day	11% 3 9% 31% 32% 14%	300
	21st to end	Day	14% 8% 19% 29% 23% 8%	330
November	1st to 10th	Day	14% 4 16% 32% 26% 7%	273
	11th to 20th	Day	20% 4 16% 30% 25% 5%	270
	21st to end	Day	21% 7% 33% 23% 13% 3	270
December	1st to 10th	Day	18% 3 23% 31% 19% 7%	270
	11th to 20th	Day	24% 9% 24% 27% 16%	270
	21st to end	Day	17% 10% 26% 32% 12% 3	297
January	1st to 10th	Night	20% 7% 25% 37% 11% 1	950
	11th to 20th	Night	21% 7% 28% 37% 8%	950
	21st to end	Night	20% 8% 28% 37% 7%	851
February	1st to 10th	Night	19% 9% 35% 31% 6% 1	760
	11th to 20th	Night	22% 7% 37% 28% 6%	744
	21st to end	Night	20% 11% 41% 24% 4	628
March	1st to 10th	Night	21% 10% 40% 25% 4	584
	11th to 20th	Night	17% 10% 39% 30% 3	570
	21st to end	Night	13% 9% 47% 28% 3	627
April	1st to 10th	Night	12% 9% 52% 24% 3	570
	11th to 20th	Night	16% 9% 44% 27% 4	563
	21st to end	Night	13% 12% 45% 24% 4 1	570
May	1st to 10th	Night	12% 7% 54% 25% 3	570
	11th to 20th	Night	11% 4 42% 35% 7%	561
	21st to end	Night	7% 5% 39% 42% 6%	617
June	1st to 10th	Night	4 3 24% 52% 16% 1	570
	11th to 20th	Night	5% 29% 53% 13%	570
	21st to end	Night	4 2 21% 50% 22% 1	570
July	1st to 10th	Night	6% 1 14% 54% 23% 2	555
	11th to 20th	Night	4 1 12% 56% 26% 2	552
	21st to end	Night	4 1 10% 57% 27% 1	624
August	1st to 10th	Night	1 1 11% 59% 26% 2	567
	11th to 20th	Night	4 1 11% 55% 27% 2	564
	21st to end	Night	6% 1 5% 47% 37% 3	627
September	1st to 10th	Night	7% 2 6% 46% 35% 5%	570
	11th to 20th	Night	10% 2 7% 35% 42% 4	570
	21st to end	Night	9% 11% 40% 36% 4	570
October	1st to 10th	Night	5% 1 12% 45% 35% 2	570
	11th to 20th	Night	12% 2 21% 47% 17% 2	646
	21st to end	Night	11% 5% 25% 39% 20% 1	836
November	1st to 10th	Night	11% 4 22% 40% 21% 2	748
	11th to 20th	Night	14% 4 22% 41% 17% 2	821
	21st to end	Night	17% 4 25% 37% 16% 1	950
December	1st to 10th	Night	20% 4 23% 37% 15% 1	950
	11th to 20th	Night	23% 6% 26% 35% 10%	950
	21st to end	Night	19% 6% 26% 39% 10%	1045

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