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 2026-10-14.

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 4 4 6% 8% 46%	149003
	Night	12% 6% 2 5% 3 3 3 3 5% 7% 50%	143163
Transparency	Day	35% 6% 12% 23% 16% 8%	152795
	Night	33% 6% 14% 22% 16% 10%	147425
Seeing	Day	11% 5% 20% 31% 24% 8%	17195
	Night	13% 5% 27% 39% 15% 1	27055

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% 8% 2 5% 3 3 3 2 4 4 50%	5289
	11th to 20th	Day	14% 7% 2 5% 3 3 3 2 4 5% 52%	5325
	21st to end	Day	24% 9% 2 5% 3 3 4 3 5% 7% 36%	6468
February	1st to 10th	Day	16% 9% 3 6% 3 3 3 3 4 5% 45%	2100
	11th to 20th	Day	18% 7% 2 6% 4 3 3 3 3 6% 44%	2049
	21st to end	Day	15% 6% 2 6% 3 4 4 2 5% 6% 49%	1730
March	1st to 10th	Day	11% 6% 2 6% 4 4 4 3 5% 8% 46%	5015
	11th to 20th	Day	14% 7% 3 6% 3 3 3 3 3 4 51%	5090
	21st to end	Day	13% 7% 2 6% 4 3 3 3 4 6% 48%	5583
April	1st to 10th	Day	11% 7% 2 5% 5% 4 5% 4 7% 7% 45%	2310
	11th to 20th	Day	14% 7% 3 7% 5% 4 3 3 6% 5% 42%	2286
	21st to end	Day	11% 7% 3 6% 5% 4 5% 4 5% 6% 44%	2574
May	1st to 10th	Day	15% 8% 3 8% 5% 5% 5% 4 6% 8% 34%	7617
	11th to 20th	Day	7% 5% 2 6% 4 5% 4 4 6% 9% 48%	7627
	21st to end	Day	8% 6% 2 7% 5% 5% 5% 5% 8% 9% 39%	8392
June	1st to 10th	Day	4 3 2 4 5% 4 6% 6% 8% 10% 48%	2730
	11th to 20th	Day	5% 4 1 5% 5% 5% 6% 5% 6% 9% 48%	2730
	21st to end	Day	6% 4 2 5% 7% 6% 6% 6% 8% 10% 39%	2730
July	1st to 10th	Day	7% 5% 2 7% 5% 5% 5% 4 7% 10% 42%	7680
	11th to 20th	Day	6% 6% 3 7% 5% 6% 6% 5% 8% 11% 36%	7680
	21st to end	Day	4 3 2 5% 4 5% 5% 5% 6% 10% 50%	8337
August	1st to 10th	Day	1 2 1 2 2 3 4 4 7% 10% 63%	5760
	11th to 20th	Day	2 2 1 3 3 3 5% 4 8% 12% 58%	5483
	21st to end	Day	3 2 1 5% 4 5% 5% 5% 7% 12% 50%	5774
September	1st to 10th	Day	8% 6% 3 6% 6% 6% 6% 5% 8% 9% 37%	2310
	11th to 20th	Day	9% 5% 2 7% 5% 6% 5% 4 7% 10% 41%	2310
	21st to end	Day	7% 5% 2 5% 5% 5% 5% 4 7% 8% 47%	2310
October	1st to 10th	Day	6% 4 2 5% 4 4 4 4 6% 7% 54%	2310
	11th to 20th	Day	11% 4 1 4 3 4 5% 3 6% 7% 52%	2132
	21st to end	Day	9% 4 2 4 3 3 4 2 4 5% 61%	2200
November	1st to 10th	Day	10% 6% 2 6% 4 4 4 3 5% 7% 48%	2058
	11th to 20th	Day	12% 6% 2 6% 3 3 3 3 5% 6% 51%	2026
	21st to end	Day	15% 8% 3 7% 5% 4 4 3 5% 6% 42%	1890
December	1st to 10th	Day	32% 10% 3 5% 3 3 3 2 3 5% 32%	3030
	11th to 20th	Day	15% 8% 3 7% 5% 5% 3 3 4 6% 41%	3481
	21st to end	Day	10% 6% 2 5% 4 4 4 3 4 6% 53%	4587
January	1st to 10th	Night	16% 7% 2 5% 3 2 3 2 4 6% 50%	7634
	11th to 20th	Night	13% 5% 2 5% 3 3 3 2 4 6% 55%	7680
	21st to end	Night	26% 7% 2 5% 3 3 3 3 5% 7% 35%	7788
February	1st to 10th	Night	15% 7% 2 4 4 4 4 3 4 7% 47%	2520
	11th to 20th	Night	19% 7% 2 4 3 2 3 2 4 7% 48%	2458
	21st to end	Night	15% 6% 2 5% 4 3 3 3 4 6% 49%	2076
March	1st to 10th	Night	16% 8% 2 6% 3 4 3 3 5% 6% 44%	5058
	11th to 20th	Night	16% 7% 2 6% 3 3 3 2 3 5% 50%	5090
	21st to end	Night	16% 7% 2 4 3 3 3 3 5% 6% 50%	5588
April	1st to 10th	Night	10% 7% 2 5% 4 3 5% 4 7% 8% 44%	2310
	11th to 20th	Night	14% 6% 2 5% 4 4 4 3 5% 7% 47%	2283
	21st to end	Night	14% 8% 3 7% 4 4 5% 3 6% 7% 40%	2037
May	1st to 10th	Night	20% 9% 3 7% 4 4 4 4 6% 7% 32%	5266
	11th to 20th	Night	10% 6% 2 5% 3 4 4 4 6% 10% 47%	5265
	21st to end	Night	10% 8% 3 8% 4 4 5% 4 7% 11% 38%	5793
June	1st to 10th	Night	5% 3 1 4 2 3 3 4 7% 10% 58%	1890
	11th to 20th	Night	5% 2 1 4 2 3 4 4 5% 9% 62%	1890
	21st to end	Night	3 4 2 5% 4 3 4 4 6% 10% 55%	1890
July	1st to 10th	Night	5% 5% 2 6% 4 5% 5% 4 6% 10% 50%	5308
	11th to 20th	Night	6% 5% 2 6% 5% 4 5% 4 7% 10% 45%	5307
	21st to end	Night	4 4 2 5% 4 3 4 4 6% 8% 58%	5770
August	1st to 10th	Night	1 1 2 1 2 2 2 3 9% 77%	4390
	11th to 20th	Night	2 2 1 3 3 3 4 3 6% 10% 62%	4583
	21st to end	Night	2 2 1 3 3 3 3 3 6% 11% 64%	5359
September	1st to 10th	Night	5% 5% 2 6% 5% 5% 5% 3 7% 9% 47%	2310
	11th to 20th	Night	7% 5% 2 6% 3 4 4 3 6% 9% 49%	2310
	21st to end	Night	6% 4 2 5% 3 4 4 3 6% 9% 55%	2310
October	1st to 10th	Night	5% 3 1 3 2 3 4 3 5% 7% 64%	2310
	11th to 20th	Night	10% 4 2 3 3 3 3 2 4 5% 61%	2313
	21st to end	Night	9% 3 1 3 2 2 2 2 4 5% 65%	2640
November	1st to 10th	Night	11% 5% 2 4 3 4 3 3 5% 6% 54%	2460
	11th to 20th	Night	12% 4 1 5% 3 3 3 3 5% 6% 55%	2588
	21st to end	Night	16% 6% 2 6% 4 3 4 2 5% 6% 46%	2730
December	1st to 10th	Night	34% 10% 3 5% 2 2 2 2 3 4 33%	4380
	11th to 20th	Night	12% 7% 3 6% 4 3 4 3 5% 6% 47%	4946
	21st to end	Night	11% 5% 2 5% 3 3 3 3 4 6% 56%	6633

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	40% 4 9% 16% 21% 11%	5290
	11th to 20th	Day	36% 3 4 17% 25% 15%	5325
	21st to end	Day	49% 3 6% 15% 19% 9%	6468
February	1st to 10th	Day	43% 4 7% 10% 20% 16%	2100
	11th to 20th	Day	42% 5% 8% 16% 18% 11%	2059
	21st to end	Day	38% 6% 7% 18% 20% 12%	1730
March	1st to 10th	Day	37% 5% 8% 19% 12% 19%	5015
	11th to 20th	Day	39% 4 5% 9% 18% 25%	5090
	21st to end	Day	36% 6% 9% 21% 18% 11%	5585
April	1st to 10th	Day	37% 6% 10% 17% 17% 13%	2310
	11th to 20th	Day	43% 5% 9% 17% 14% 12%	2286
	21st to end	Day	40% 7% 9% 18% 16% 10%	2574
May	1st to 10th	Day	45% 7% 12% 22% 11% 4	7655
	11th to 20th	Day	32% 7% 13% 24% 17% 7%	7631
	21st to end	Day	37% 8% 12% 31% 11% 1	8405
June	1st to 10th	Day	28% 7% 16% 28% 19% 2	2730
	11th to 20th	Day	31% 8% 12% 25% 20% 4	2730
	21st to end	Day	36% 10% 15% 25% 12% 2	2730
July	1st to 10th	Day	35% 7% 24% 29% 4	7616
	11th to 20th	Day	40% 9% 22% 22% 7%	7611
	21st to end	Day	27% 8% 18% 35% 13% 1	8155
August	1st to 10th	Day	15% 7% 17% 42% 19% 1	5746
	11th to 20th	Day	18% 8% 28% 37% 8% 1	5519
	21st to end	Day	25% 10% 17% 32% 15% 1	5773
September	1st to 10th	Day	41% 10% 15% 15% 14% 5%	2310
	11th to 20th	Day	38% 9% 15% 21% 14% 3	2310
	21st to end	Day	32% 8% 13% 21% 16% 10%	2310
October	1st to 10th	Day	22% 5% 7% 12% 23% 32%	3700
	11th to 20th	Day	23% 7% 11% 19% 20% 20%	3424
	21st to end	Day	24% 6% 8% 17% 29% 17%	3538
November	1st to 10th	Day	36% 5% 9% 17% 20% 13%	2058
	11th to 20th	Day	35% 4 10% 18% 19% 15%	2026
	21st to end	Day	44% 4 7% 16% 17% 12%	1890
December	1st to 10th	Day	58% 3 5% 11% 17% 6%	3030
	11th to 20th	Day	42% 6% 7% 17% 16% 13%	3479
	21st to end	Day	32% 4 6% 21% 22% 15%	4587
January	1st to 10th	Night	37% 4 9% 16% 18% 15%	7635
	11th to 20th	Night	32% 3 5% 18% 22% 20%	7680
	21st to end	Night	49% 4 5% 14% 17% 10%	7788
February	1st to 10th	Night	40% 4 9% 13% 16% 18%	2520
	11th to 20th	Night	39% 3 9% 18% 17% 13%	2458
	21st to end	Night	38% 4 8% 19% 19% 12%	2076
March	1st to 10th	Night	43% 5% 8% 16% 13% 14%	5058
	11th to 20th	Night	40% 4 6% 11% 16% 23%	5090
	21st to end	Night	36% 5% 12% 19% 18% 10%	5588
April	1st to 10th	Night	38% 7% 13% 19% 13% 11%	2310
	11th to 20th	Night	39% 6% 11% 16% 13% 15%	2283
	21st to end	Night	43% 6% 11% 17% 14% 9%	2037
May	1st to 10th	Night	51% 7% 12% 17% 11% 4	5293
	11th to 20th	Night	33% 6% 14% 23% 18% 6%	5266
	21st to end	Night	41% 8% 17% 27% 6%	5805
June	1st to 10th	Night	22% 7% 20% 31% 18% 2	1890
	11th to 20th	Night	20% 6% 15% 33% 23% 3	1890
	21st to end	Night	24% 9% 22% 30% 14% 1	1890
July	1st to 10th	Night	30% 7% 28% 32% 3	5265
	11th to 20th	Night	34% 9% 28% 23% 6%	5256
	21st to end	Night	24% 7% 21% 35% 11% 1	5641
August	1st to 10th	Night	8% 4 22% 48% 17%	4380
	11th to 20th	Night	18% 6% 35% 36% 5%	4613
	21st to end	Night	15% 8% 26% 38% 13%	5359
September	1st to 10th	Night	31% 10% 21% 21% 12% 5%	2310
	11th to 20th	Night	30% 8% 18% 26% 16% 3	2310
	21st to end	Night	25% 6% 15% 28% 17% 8%	2310
October	1st to 10th	Night	14% 6% 9% 19% 22% 31%	3700
	11th to 20th	Night	19% 4 11% 22% 27% 17%	3734
	21st to end	Night	19% 3 9% 21% 31% 16%	4252
November	1st to 10th	Night	30% 6% 9% 18% 23% 12%	2460
	11th to 20th	Night	31% 5% 12% 18% 19% 15%	2588
	21st to end	Night	38% 5% 9% 18% 18% 11%	2730
December	1st to 10th	Night	59% 3 5% 10% 13% 8%	4380
	11th to 20th	Night	38% 6% 9% 16% 16% 15%	4947
	21st to end	Night	30% 5% 7% 19% 23% 16%	6633

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	20% 7% 32% 25% 13% 2	330
	11th to 20th	Day	21% 9% 29% 30% 9% 2	330
	21st to end	Day	22% 8% 32% 26% 11% 1	363
February	1st to 10th	Day	19% 9% 28% 28% 15% 2	330
	11th to 20th	Day	20% 11% 35% 24% 9% 2	330
	21st to end	Day	19% 8% 36% 30% 7%	273
March	1st to 10th	Day	19% 11% 38% 25% 7%	330
	11th to 20th	Day	15% 10% 42% 25% 8%	330
	21st to end	Day	12% 10% 37% 32% 7% 2	363
April	1st to 10th	Day	16% 10% 34% 31% 10%	330
	11th to 20th	Day	17% 13% 32% 27% 11% 1	324
	21st to end	Day	13% 10% 43% 27% 5% 1	594
May	1st to 10th	Day	14% 12% 39% 28% 7%	753
	11th to 20th	Day	11% 9% 35% 31% 13% 2	775
	21st to end	Day	11% 5% 28% 39% 17% 1	844
June	1st to 10th	Day	6% 2 17% 43% 28% 5%	780
	11th to 20th	Day	6% 1 18% 44% 25% 6%	780
	21st to end	Day	7% 1 11% 38% 30% 12%	780
July	1st to 10th	Day	8% 2 9% 35% 36% 10%	771
	11th to 20th	Day	4 1 7% 38% 41% 10%	768
	21st to end	Day	4 1 6% 33% 43% 12%	849
August	1st to 10th	Day	2 1 4 33% 40% 20%	665
	11th to 20th	Day	3 1 5% 34% 37% 19%	557
	21st to end	Day	5% 1 4 22% 36% 32%	491
September	1st to 10th	Day	9% 1 4 20% 43% 23%	360
	11th to 20th	Day	7% 1 4 18% 39% 31%	360
	21st to end	Day	8% 1 6% 21% 41% 25%	360
October	1st to 10th	Day	8% 2 9% 24% 38% 20%	360
	11th to 20th	Day	10% 3 8% 31% 35% 14%	339
	21st to end	Day	13% 8% 18% 30% 24% 8%	363
November	1st to 10th	Day	11% 5% 18% 33% 24% 8%	330
	11th to 20th	Day	16% 4 17% 32% 24% 6%	330
	21st to end	Day	19% 8% 32% 25% 14% 4	330
December	1st to 10th	Day	22% 4 23% 29% 17% 6%	330
	11th to 20th	Day	24% 9% 21% 27% 18% 1	330
	21st to end	Day	15% 10% 24% 34% 15% 2	363
January	1st to 10th	Night	20% 7% 25% 36% 11% 1	1050
	11th to 20th	Night	20% 7% 30% 36% 8%	1050
	21st to end	Night	21% 8% 27% 36% 7%	940
February	1st to 10th	Night	19% 9% 34% 32% 6%	840
	11th to 20th	Night	22% 7% 38% 27% 6%	824
	21st to end	Night	20% 10% 40% 26% 3	692
March	1st to 10th	Night	22% 11% 39% 24% 3	646
	11th to 20th	Night	16% 11% 40% 29% 4	630
	21st to end	Night	14% 9% 46% 28% 3	693
April	1st to 10th	Night	13% 9% 51% 24% 3	630
	11th to 20th	Night	17% 10% 44% 26% 4	623
	21st to end	Night	15% 12% 46% 23% 4	630
May	1st to 10th	Night	14% 8% 52% 24% 3	630
	11th to 20th	Night	11% 5% 43% 33% 7%	621
	21st to end	Night	8% 5% 40% 40% 7%	683
June	1st to 10th	Night	5% 3 25% 51% 16% 1	630
	11th to 20th	Night	6% 29% 51% 13%	630
	21st to end	Night	3 2 22% 50% 22% 1	630
July	1st to 10th	Night	6% 2 14% 55% 22% 2	615
	11th to 20th	Night	4 1 13% 56% 24% 1	612
	21st to end	Night	4 1 11% 57% 26% 1	690
August	1st to 10th	Night	1 1 10% 59% 26% 2	627
	11th to 20th	Night	4 1 12% 55% 26% 2	624
	21st to end	Night	5% 1 5% 48% 37% 3	693
September	1st to 10th	Night	6% 2 7% 46% 34% 5%	630
	11th to 20th	Night	9% 1 8% 37% 41% 3	630
	21st to end	Night	8% 1 12% 41% 35% 4	630
October	1st to 10th	Night	5% 1 12% 44% 35% 2	630
	11th to 20th	Night	11% 1 20% 48% 17% 2	689
	21st to end	Night	10% 5% 26% 39% 19% 1	880
November	1st to 10th	Night	11% 5% 22% 40% 20% 1	820
	11th to 20th	Night	14% 4 23% 42% 17% 1	908
	21st to end	Night	18% 5% 25% 36% 15% 1	1050
December	1st to 10th	Night	22% 4 23% 36% 14% 1	1050
	11th to 20th	Night	22% 6% 25% 36% 11%	1050
	21st to end	Night	19% 6% 25% 39% 10%	1155

Page generated at 2026-10-11 04:06:30. Version ac07

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