Bastrop State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bastrop State Park clear sky chart from 2005-11-06 to 2026-01-17.

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	12% 6% 2 6% 4 4 4 4 6% 8% 44%	127395
	Night	13% 6% 2 5% 3 3 3 3 5% 7% 49%	124584
Transparency	Day	36% 5% 10% 21% 18% 9%	131138
	Night	35% 5% 11% 20% 19% 11%	128904
Seeing	Day	14% 7% 20% 28% 24% 8%	16395
	Night	15% 7% 25% 35% 16% 1	26380

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	17% 11% 3 6% 3 3 3 2 4 5% 44%	4167
	11th to 20th	Day	16% 5% 2 5% 2 2 4 2 5% 6% 51%	4134
	21st to end	Day	28% 9% 2 5% 3 2 2 1 3 5% 39%	4640
February	1st to 10th	Day	21% 7% 2 6% 4 3 3 3 3 5% 42%	2000
	11th to 20th	Day	20% 8% 3 6% 3 3 3 2 4 6% 43%	1949
	21st to end	Day	17% 9% 3 6% 3 2 4 3 4 4 46%	1684
March	1st to 10th	Day	13% 7% 2 6% 4 4 4 3 5% 6% 47%	4936
	11th to 20th	Day	14% 7% 2 6% 4 4 3 3 4 6% 48%	4980
	21st to end	Day	17% 9% 3 6% 4 3 3 3 4 6% 42%	5462
April	1st to 10th	Day	14% 9% 3 6% 5% 4 4 4 5% 6% 41%	2200
	11th to 20th	Day	13% 8% 3 8% 5% 4 4 3 4 6% 41%	2196
	21st to end	Day	14% 8% 2 6% 4 4 4 3 5% 7% 43%	2489
May	1st to 10th	Day	18% 7% 3 7% 5% 5% 5% 4 6% 7% 34%	5862
	11th to 20th	Day	10% 6% 2 7% 4 4 4 4 6% 8% 44%	5862
	21st to end	Day	10% 7% 3 7% 5% 5% 6% 5% 8% 10% 35%	6434
June	1st to 10th	Day	5% 4 2 5% 4 4 5% 5% 7% 10% 49%	2600
	11th to 20th	Day	6% 5% 2 5% 5% 5% 6% 4 6% 10% 48%	2600
	21st to end	Day	5% 7% 2 6% 6% 7% 6% 5% 8% 10% 38%	2600
July	1st to 10th	Day	9% 6% 3 7% 5% 5% 5% 5% 7% 10% 38%	5900
	11th to 20th	Day	5% 5% 2 6% 5% 5% 6% 6% 7% 13% 41%	5900
	21st to end	Day	7% 6% 2 6% 5% 5% 6% 4 8% 12% 38%	6422
August	1st to 10th	Day	1 2 1 2 3 3 3 3 7% 10% 65%	4234
	11th to 20th	Day	3 2 1 3 3 4 5% 5% 9% 13% 52%	4021
	21st to end	Day	4 3 2 6% 5% 5% 6% 6% 8% 11% 45%	4025
September	1st to 10th	Day	6% 7% 3 7% 6% 5% 5% 4 5% 8% 43%	2200
	11th to 20th	Day	8% 6% 2 7% 6% 6% 6% 5% 7% 7% 41%	2200
	21st to end	Day	6% 4 2 5% 5% 5% 6% 5% 6% 9% 48%	2200
October	1st to 10th	Day	5% 4 2 4 4 3 4 4 5% 8% 58%	2200
	11th to 20th	Day	13% 5% 2 4 3 3 3 3 3 5% 56%	2005
	21st to end	Day	11% 4 1 5% 3 4 3 2 4 6% 57%	2200
November	1st to 10th	Day	12% 7% 3 5% 3 3 4 3 5% 7% 48%	2058
	11th to 20th	Day	10% 6% 3 5% 3 4 4 3 4 5% 53%	2047
	21st to end	Day	17% 8% 2 5% 3 4 4 3 4 6% 44%	1890
December	1st to 10th	Day	25% 8% 3 6% 3 3 3 3 4 6% 37%	3030
	11th to 20th	Day	18% 8% 2 6% 4 3 3 3 4 5% 43%	3481
	21st to end	Day	14% 7% 2 5% 3 3 3 2 3 4 53%	4587
January	1st to 10th	Night	19% 8% 2 4 2 3 3 2 3 5% 48%	6018
	11th to 20th	Night	13% 4 1 3 2 3 3 3 3 5% 60%	5979
	21st to end	Night	29% 6% 2 5% 3 2 2 2 3 5% 39%	6380
February	1st to 10th	Night	19% 8% 2 5% 3 3 3 2 3 5% 45%	2400
	11th to 20th	Night	21% 7% 2 5% 2 3 2 2 3 5% 47%	2338
	21st to end	Night	21% 8% 2 5% 3 4 3 2 4 5% 43%	1945
March	1st to 10th	Night	17% 7% 2 5% 4 4 4 3 5% 7% 43%	4919
	11th to 20th	Night	17% 7% 3 5% 3 3 3 2 4 5% 47%	4980
	21st to end	Night	18% 9% 3 6% 4 3 4 2 4 5% 41%	5467
April	1st to 10th	Night	12% 7% 2 6% 4 4 4 3 6% 6% 46%	2200
	11th to 20th	Night	15% 7% 2 5% 4 3 3 2 5% 7% 45%	2151
	21st to end	Night	14% 7% 2 6% 4 2 3 3 5% 7% 46%	1906
May	1st to 10th	Night	22% 9% 3 7% 4 4 4 3 6% 7% 32%	4053
	11th to 20th	Night	9% 6% 2 6% 4 4 5% 4 6% 9% 45%	4053
	21st to end	Night	12% 7% 3 7% 4 5% 5% 4 7% 9% 37%	4443
June	1st to 10th	Night	4 3 1 4 3 3 3 3 6% 10% 59%	1800
	11th to 20th	Night	4 3 1 3 3 4 5% 4 6% 10% 57%	1800
	21st to end	Night	4 5% 2 5% 4 5% 4 4 7% 10% 50%	1800
July	1st to 10th	Night	8% 6% 2 6% 5% 4 5% 4 6% 11% 42%	4078
	11th to 20th	Night	4 4 2 5% 4 4 4 4 6% 12% 51%	4077
	21st to end	Night	6% 5% 3 6% 4 4 5% 4 7% 10% 46%	4449
August	1st to 10th	Night	1 1 2 2 2 3 3 4 9% 73%	2926
	11th to 20th	Night	2 2 1 3 2 3 4 4 8% 12% 59%	3019
	21st to end	Night	3 3 1 3 3 4 4 5% 8% 12% 55%	3873
September	1st to 10th	Night	6% 5% 2 5% 5% 4 4 4 6% 9% 50%	2200
	11th to 20th	Night	7% 6% 2 6% 5% 5% 5% 4 6% 7% 48%	2200
	21st to end	Night	7% 4 1 5% 3 4 4 3 6% 8% 53%	2200
October	1st to 10th	Night	4 4 1 3 3 3 3 3 5% 7% 65%	2200
	11th to 20th	Night	11% 4 1 4 3 3 3 3 4 5% 59%	2374
	21st to end	Night	12% 5% 1 4 2 3 3 2 3 5% 60%	2640
November	1st to 10th	Night	12% 5% 2 4 3 3 3 3 4 6% 54%	2460
	11th to 20th	Night	11% 5% 2 5% 4 3 3 2 5% 7% 54%	2567
	21st to end	Night	17% 6% 2 5% 3 4 3 3 4 6% 46%	2730
December	1st to 10th	Night	24% 9% 2 7% 3 3 3 3 4 4 38%	4380
	11th to 20th	Night	17% 10% 3 5% 3 3 3 2 3 5% 47%	4946
	21st to end	Night	15% 6% 2 4 2 3 2 2 4 4 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	45% 3 4 20% 19% 8%	4168
	11th to 20th	Day	35% 3 5% 18% 24% 15%	4134
	21st to end	Day	50% 2 3 9% 22% 14%	4640
February	1st to 10th	Day	45% 3 6% 12% 20% 14%	2000
	11th to 20th	Day	45% 3 6% 18% 17% 10%	1959
	21st to end	Day	43% 4 7% 16% 17% 14%	1684
March	1st to 10th	Day	38% 4 5% 19% 16% 17%	4936
	11th to 20th	Day	39% 3 6% 9% 16% 26%	4980
	21st to end	Day	44% 4 6% 19% 19% 7%	5464
April	1st to 10th	Day	44% 5% 7% 17% 15% 12%	2200
	11th to 20th	Day	45% 4 7% 15% 18% 11%	2196
	21st to end	Day	41% 5% 7% 20% 20% 8%	2489
May	1st to 10th	Day	47% 6% 10% 20% 13% 4	5900
	11th to 20th	Day	37% 5% 12% 19% 21% 6%	5866
	21st to end	Day	41% 7% 11% 27% 13% 2	6447
June	1st to 10th	Day	29% 6% 16% 27% 20% 2	2600
	11th to 20th	Day	31% 7% 12% 26% 19% 4	2600
	21st to end	Day	37% 10% 14% 23% 14% 2	2600
July	1st to 10th	Day	39% 8% 22% 27% 4 1	5836
	11th to 20th	Day	32% 9% 20% 28% 10% 1	5831
	21st to end	Day	35% 8% 17% 25% 13% 1	6240
August	1st to 10th	Day	15% 5% 13% 41% 25% 1	4220
	11th to 20th	Day	20% 8% 26% 35% 9% 2	4060
	21st to end	Day	29% 11% 19% 24% 15% 2	4024
September	1st to 10th	Day	38% 7% 10% 21% 16% 8%	2200
	11th to 20th	Day	39% 7% 12% 19% 18% 5%	2200
	21st to end	Day	31% 7% 9% 22% 16% 15%	2200
October	1st to 10th	Day	16% 3 7% 14% 23% 38%	3590
	11th to 20th	Day	21% 3 7% 19% 32% 18%	3245
	21st to end	Day	26% 4 5% 20% 29% 16%	3538
November	1st to 10th	Day	36% 5% 8% 18% 22% 12%	2058
	11th to 20th	Day	34% 4 8% 17% 22% 15%	2047
	21st to end	Day	43% 4 7% 16% 18% 12%	1890
December	1st to 10th	Day	50% 3 6% 15% 18% 8%	3030
	11th to 20th	Day	43% 4 7% 11% 23% 12%	3479
	21st to end	Day	36% 3 4 17% 25% 14%	4587
January	1st to 10th	Night	40% 3 5% 19% 22% 12%	6018
	11th to 20th	Night	28% 3 4 18% 31% 16%	5979
	21st to end	Night	50% 2 3 11% 19% 14%	6380
February	1st to 10th	Night	43% 4 6% 12% 19% 17%	2400
	11th to 20th	Night	42% 3 6% 17% 19% 13%	2338
	21st to end	Night	45% 3 5% 15% 17% 14%	1945
March	1st to 10th	Night	41% 6% 6% 16% 17% 14%	4919
	11th to 20th	Night	41% 4 7% 12% 13% 23%	4980
	21st to end	Night	46% 4 7% 16% 18% 9%	5467
April	1st to 10th	Night	39% 5% 9% 17% 17% 13%	2200
	11th to 20th	Night	39% 4 10% 16% 16% 15%	2151
	21st to end	Night	39% 4 9% 22% 18% 8%	1906
May	1st to 10th	Night	51% 6% 8% 19% 11% 4	4080
	11th to 20th	Night	35% 5% 11% 22% 19% 7%	4054
	21st to end	Night	40% 7% 14% 28% 10% 1	4452
June	1st to 10th	Night	21% 6% 19% 31% 21% 3	1800
	11th to 20th	Night	22% 6% 15% 32% 20% 4	1800
	21st to end	Night	29% 8% 17% 28% 16% 2	1800
July	1st to 10th	Night	37% 8% 26% 25% 4	4035
	11th to 20th	Night	26% 8% 23% 33% 10%	4026
	21st to end	Night	33% 9% 20% 25% 11% 3	4320
August	1st to 10th	Night	9% 5% 16% 45% 24%	2916
	11th to 20th	Night	17% 7% 32% 33% 10% 1	3046
	21st to end	Night	21% 11% 24% 29% 13% 2	3873
September	1st to 10th	Night	30% 7% 17% 23% 15% 8%	2200
	11th to 20th	Night	33% 7% 15% 24% 16% 6%	2200
	21st to end	Night	28% 5% 15% 21% 17% 14%	2200
October	1st to 10th	Night	13% 3 8% 17% 20% 39%	3590
	11th to 20th	Night	18% 2 8% 19% 32% 21%	3860
	21st to end	Night	22% 3 6% 23% 29% 17%	4252
November	1st to 10th	Night	32% 5% 9% 19% 22% 14%	2460
	11th to 20th	Night	32% 4 9% 20% 20% 16%	2567
	21st to end	Night	39% 3 8% 19% 17% 14%	2730
December	1st to 10th	Night	51% 3 5% 15% 18% 9%	4380
	11th to 20th	Night	41% 3 7% 10% 22% 16%	4947
	21st to end	Night	34% 3 4 16% 30% 13%	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	22% 14% 34% 23% 6% 1	330
	11th to 20th	Day	25% 13% 28% 26% 6% 1	318
	21st to end	Day	24% 17% 33% 19% 7%	330
February	1st to 10th	Day	32% 12% 28% 20% 7% 1	300
	11th to 20th	Day	30% 18% 30% 16% 5%	300
	21st to end	Day	28% 17% 35% 17% 3	249
March	1st to 10th	Day	24% 17% 34% 19% 5% 1	300
	11th to 20th	Day	21% 17% 38% 17% 6% 1	300
	21st to end	Day	20% 15% 39% 18% 8%	330
April	1st to 10th	Day	23% 14% 36% 21% 5% 1	300
	11th to 20th	Day	22% 16% 32% 22% 8% 1	314
	21st to end	Day	21% 11% 34% 25% 8% 1	589
May	1st to 10th	Day	16% 10% 36% 28% 9%	703
	11th to 20th	Day	16% 9% 26% 32% 14% 3	725
	21st to end	Day	12% 7% 25% 34% 19% 3	789
June	1st to 10th	Day	7% 2 13% 39% 31% 9%	730
	11th to 20th	Day	8% 3 12% 43% 27% 7%	730
	21st to end	Day	6% 3 11% 34% 31% 15%	730
July	1st to 10th	Day	9% 3 8% 31% 36% 14%	721
	11th to 20th	Day	5% 1 5% 29% 46% 14%	718
	21st to end	Day	5% 2 6% 27% 46% 14%	794
August	1st to 10th	Day	2 1 4 24% 51% 17%	726
	11th to 20th	Day	5% 2 3 26% 49% 16%	630
	21st to end	Day	7% 2 3 23% 33% 32%	413
September	1st to 10th	Day	6% 2 7% 28% 36% 22%	330
	11th to 20th	Day	4 3 6% 27% 41% 20%	330
	21st to end	Day	10% 2 5% 29% 38% 16%	330
October	1st to 10th	Day	3 1 11% 34% 38% 12%	330
	11th to 20th	Day	12% 4 21% 31% 26% 7%	330
	21st to end	Day	19% 9% 25% 23% 19% 5%	363
November	1st to 10th	Day	18% 6% 22% 32% 16% 6%	330
	11th to 20th	Day	17% 7% 26% 30% 17% 4	330
	21st to end	Day	24% 13% 31% 21% 8% 2	330
December	1st to 10th	Day	22% 8% 35% 20% 10% 4	330
	11th to 20th	Day	25% 13% 28% 23% 10% 1	330
	21st to end	Day	22% 10% 34% 23% 8% 2	363
January	1st to 10th	Night	22% 10% 30% 30% 8%	1050
	11th to 20th	Night	22% 12% 29% 29% 8%	1031
	21st to end	Night	23% 9% 31% 30% 6%	1055
February	1st to 10th	Night	25% 12% 30% 29% 5%	800
	11th to 20th	Night	26% 11% 34% 25% 4	784
	21st to end	Night	27% 13% 39% 19% 3	625
March	1st to 10th	Night	22% 11% 39% 25% 4	600
	11th to 20th	Night	20% 11% 36% 28% 4	600
	21st to end	Night	17% 10% 42% 26% 4 1	660
April	1st to 10th	Night	16% 11% 41% 29% 3	600
	11th to 20th	Night	19% 10% 42% 24% 6%	593
	21st to end	Night	16% 12% 40% 24% 7% 1	600
May	1st to 10th	Night	16% 9% 44% 27% 5%	600
	11th to 20th	Night	12% 8% 35% 34% 10% 1	591
	21st to end	Night	11% 5% 32% 38% 14%	650
June	1st to 10th	Night	5% 3 18% 48% 25% 1	600
	11th to 20th	Night	5% 2 26% 51% 15% 1	600
	21st to end	Night	4 4 14% 45% 30% 4	600
July	1st to 10th	Night	7% 2 9% 49% 31% 3	585
	11th to 20th	Night	3 2 11% 49% 32% 3	582
	21st to end	Night	5% 1 8% 50% 33% 3	657
August	1st to 10th	Night	1 7% 56% 32% 3	597
	11th to 20th	Night	5% 1 6% 54% 30% 5%	594
	21st to end	Night	5% 5% 39% 44% 7%	660
September	1st to 10th	Night	7% 2 8% 40% 38% 5%	600
	11th to 20th	Night	9% 3 8% 37% 40% 4	600
	21st to end	Night	10% 2 13% 37% 35% 4	600
October	1st to 10th	Night	4 1 12% 48% 30% 5%	600
	11th to 20th	Night	13% 4 21% 42% 19% 2	774
	21st to end	Night	14% 8% 26% 32% 18% 2	880
November	1st to 10th	Night	13% 5% 23% 39% 20% 1	820
	11th to 20th	Night	14% 6% 26% 38% 14% 1	887
	21st to end	Night	19% 11% 27% 29% 13% 1	1050
December	1st to 10th	Night	22% 8% 28% 31% 12%	1050
	11th to 20th	Night	23% 10% 27% 31% 8%	1050
	21st to end	Night	20% 10% 30% 32% 7%	1155

Page generated at 2026-01-14 00:14:31. Version ac07

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