Battleship Texas State Historic Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Battleship Texas State Historic Site clear sky chart from 2005-11-06 to 2025-09-19.

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	13% 6% 2 6% 5% 5% 5% 4 6% 8% 40%	126028
	Night	15% 7% 2 5% 4 3 4 3 5% 7% 44%	123243
Transparency	Day	38% 9% 13% 19% 15% 7%	129663
	Night	37% 7% 13% 19% 16% 8%	127658
Seeing	Day	12% 6% 19% 27% 24% 12%	16018
	Night	15% 5% 19% 32% 25% 3	25780

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	22% 11% 3 6% 4 3 3 2 3 4 39%	4077
	11th to 20th	Day	16% 6% 2 5% 4 3 3 2 3 6% 50%	4080
	21st to end	Day	29% 8% 2 6% 4 3 3 3 4 6% 32%	4488
February	1st to 10th	Day	22% 9% 3 7% 4 4 4 4 4 6% 34%	1870
	11th to 20th	Day	23% 9% 3 6% 4 3 4 3 4 6% 36%	1999
	21st to end	Day	21% 8% 2 7% 3 4 4 3 4 5% 38%	1815
March	1st to 10th	Day	18% 8% 3 7% 4 4 4 4 5% 7% 36%	4936
	11th to 20th	Day	14% 5% 2 7% 4 5% 4 3 4 5% 45%	4980
	21st to end	Day	20% 7% 2 7% 5% 4 4 3 5% 6% 39%	5462
April	1st to 10th	Day	16% 7% 3 8% 5% 4 5% 4 6% 5% 38%	2200
	11th to 20th	Day	16% 7% 2 7% 5% 4 4 3 5% 6% 39%	2349
	21st to end	Day	11% 7% 2 7% 5% 4 5% 5% 6% 7% 42%	2400
May	1st to 10th	Day	18% 8% 3 8% 6% 5% 5% 5% 6% 7% 28%	5405
	11th to 20th	Day	11% 6% 3 7% 5% 4 4 4 5% 8% 45%	5858
	21st to end	Day	9% 6% 2 6% 5% 5% 6% 5% 7% 11% 36%	6434
June	1st to 10th	Day	6% 5% 2 7% 5% 4 6% 5% 9% 10% 42%	2600
	11th to 20th	Day	5% 4 2 6% 6% 6% 7% 6% 9% 10% 39%	2600
	21st to end	Day	6% 6% 3 7% 7% 8% 9% 6% 8% 10% 31%	2600
July	1st to 10th	Day	7% 5% 2 7% 6% 7% 7% 7% 9% 14% 29%	5900
	11th to 20th	Day	6% 6% 3 9% 7% 7% 7% 5% 9% 12% 30%	5900
	21st to end	Day	10% 7% 3 7% 5% 6% 5% 5% 7% 10% 35%	6422
August	1st to 10th	Day	2 2 1 3 4 4 5% 5% 8% 11% 56%	4234
	11th to 20th	Day	3 2 1 5% 4 5% 6% 5% 9% 14% 48%	3952
	21st to end	Day	8% 4 2 6% 6% 7% 7% 6% 9% 9% 36%	4296
September	1st to 10th	Day	7% 6% 2 7% 5% 6% 7% 6% 8% 10% 36%	2200
	11th to 20th	Day	14% 6% 2 7% 5% 5% 5% 4 7% 7% 37%	2178
	21st to end	Day	10% 5% 2 5% 4 4 4 4 6% 8% 49%	2090
October	1st to 10th	Day	8% 4 2 4 4 2 4 4 6% 8% 55%	1956
	11th to 20th	Day	10% 4 2 5% 4 4 3 3 5% 6% 53%	1900
	21st to end	Day	13% 5% 2 5% 3 3 4 3 3 6% 54%	2090
November	1st to 10th	Day	11% 5% 2 5% 5% 6% 4 3 6% 7% 46%	1958
	11th to 20th	Day	11% 5% 3 6% 4 4 4 4 6% 5% 47%	2000
	21st to end	Day	16% 7% 2 7% 4 4 4 3 5% 6% 43%	1980
December	1st to 10th	Day	24% 9% 2 6% 4 4 3 2 5% 7% 35%	2940
	11th to 20th	Day	13% 7% 2 7% 5% 4 4 4 5% 6% 43%	3391
	21st to end	Day	16% 6% 2 5% 4 4 4 3 5% 6% 46%	4488
January	1st to 10th	Night	20% 7% 2 6% 3 3 4 3 4 6% 42%	5888
	11th to 20th	Night	17% 8% 2 5% 3 3 3 2 4 5% 48%	5900
	21st to end	Night	30% 9% 2 6% 3 3 3 2 4 6% 32%	6490
February	1st to 10th	Night	21% 9% 3 6% 4 3 4 3 4 6% 38%	2545
	11th to 20th	Night	22% 10% 3 5% 3 2 3 2 4 5% 41%	2286
	21st to end	Night	23% 8% 2 6% 4 3 2 3 4 5% 39%	1815
March	1st to 10th	Night	24% 10% 3 6% 3 3 3 3 4 5% 36%	4919
	11th to 20th	Night	19% 8% 3 6% 4 3 3 2 4 5% 43%	4980
	21st to end	Night	18% 9% 2 6% 4 4 3 3 4 5% 41%	5467
April	1st to 10th	Night	17% 6% 2 7% 5% 4 4 4 6% 6% 39%	2200
	11th to 20th	Night	19% 6% 2 4 4 3 3 3 6% 6% 45%	1998
	21st to end	Night	14% 7% 2 6% 4 4 4 4 6% 7% 43%	2000
May	1st to 10th	Night	26% 9% 2 6% 5% 4 4 3 5% 7% 27%	4476
	11th to 20th	Night	16% 7% 2 6% 4 4 4 4 5% 7% 41%	4053
	21st to end	Night	16% 8% 3 6% 5% 5% 5% 5% 8% 11% 30%	4443
June	1st to 10th	Night	5% 3 1 4 3 3 4 3 6% 12% 56%	1800
	11th to 20th	Night	6% 3 1 3 3 3 3 4 7% 12% 54%	1800
	21st to end	Night	6% 5% 2 5% 6% 4 5% 5% 9% 11% 44%	1800
July	1st to 10th	Night	5% 5% 3 5% 4 4 5% 4 8% 14% 43%	4078
	11th to 20th	Night	3 3 2 6% 5% 5% 6% 5% 6% 11% 49%	4077
	21st to end	Night	7% 5% 2 7% 4 5% 5% 4 6% 9% 45%	4449
August	1st to 10th	Night	1 1 1 2 2 2 3 3 5% 10% 69%	2926
	11th to 20th	Night	2 2 1 3 2 3 3 4 7% 14% 60%	3099
	21st to end	Night	5% 3 1 4 4 5% 5% 5% 9% 12% 47%	3586
September	1st to 10th	Night	6% 5% 3 5% 5% 4 4 5% 7% 11% 46%	2197
	11th to 20th	Night	11% 6% 2 6% 3 4 4 3 5% 9% 46%	2178
	21st to end	Night	9% 4 2 4 4 3 3 4 6% 7% 54%	2090
October	1st to 10th	Night	5% 4 2 4 4 3 3 3 5% 6% 61%	2204
	11th to 20th	Night	10% 3 2 3 3 3 3 2 5% 7% 60%	2280
	21st to end	Night	11% 5% 2 4 3 3 3 3 4 5% 60%	2508
November	1st to 10th	Night	11% 6% 1 4 3 4 3 3 5% 7% 53%	2340
	11th to 20th	Night	12% 5% 2 5% 4 4 3 3 5% 6% 52%	2400
	21st to end	Night	15% 6% 2 5% 4 3 4 3 4 5% 47%	2415
December	1st to 10th	Night	22% 10% 4 7% 5% 3 3 2 4 6% 34%	4250
	11th to 20th	Night	15% 8% 3 7% 4 4 4 3 4 5% 43%	4816
	21st to end	Night	16% 7% 2 6% 3 4 3 3 3 6% 47%	6490

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	50% 4 4 18% 17% 7%	4078
	11th to 20th	Day	37% 4 5% 20% 22% 12%	4080
	21st to end	Day	53% 3 3 13% 15% 12%	4488
February	1st to 10th	Day	50% 6% 6% 13% 15% 11%	1870
	11th to 20th	Day	51% 6% 6% 13% 16% 8%	2009
	21st to end	Day	48% 6% 8% 14% 14% 10%	1815
March	1st to 10th	Day	45% 8% 9% 14% 13% 11%	4936
	11th to 20th	Day	38% 7% 7% 11% 20% 16%	4980
	21st to end	Day	44% 7% 8% 18% 19% 4	5464
April	1st to 10th	Day	45% 8% 8% 16% 14% 9%	2200
	11th to 20th	Day	44% 7% 9% 15% 16% 9%	2349
	21st to end	Day	37% 8% 11% 18% 19% 6%	2400
May	1st to 10th	Day	49% 10% 11% 17% 10% 3	5440
	11th to 20th	Day	36% 8% 12% 21% 20% 2	5862
	21st to end	Day	36% 11% 16% 27% 9% 1	6447
June	1st to 10th	Day	32% 12% 17% 24% 15% 1	2600
	11th to 20th	Day	33% 11% 16% 25% 13% 2	2600
	21st to end	Day	40% 14% 18% 20% 7%	2600
July	1st to 10th	Day	37% 13% 29% 18% 2	5836
	11th to 20th	Day	40% 13% 26% 17% 3	5831
	21st to end	Day	41% 11% 19% 24% 6%	6240
August	1st to 10th	Day	18% 10% 17% 39% 16%	4220
	11th to 20th	Day	22% 12% 33% 29% 4 1	3990
	21st to end	Day	37% 15% 16% 18% 13% 1	4295
September	1st to 10th	Day	38% 14% 15% 16% 13% 4	2200
	11th to 20th	Day	41% 11% 12% 18% 15% 3	2178
	21st to end	Day	32% 8% 14% 19% 16% 11%	2090
October	1st to 10th	Day	19% 5% 7% 15% 15% 39%	3242
	11th to 20th	Day	21% 5% 6% 18% 36% 14%	3140
	21st to end	Day	25% 6% 6% 17% 34% 13%	3428
November	1st to 10th	Day	36% 7% 11% 19% 19% 9%	1958
	11th to 20th	Day	37% 6% 10% 14% 20% 14%	2000
	21st to end	Day	42% 6% 9% 15% 18% 11%	1980
December	1st to 10th	Day	49% 5% 7% 15% 20% 4	2940
	11th to 20th	Day	39% 7% 10% 15% 19% 10%	3389
	21st to end	Day	38% 6% 6% 16% 22% 11%	4488
January	1st to 10th	Night	42% 6% 7% 20% 18% 8%	5888
	11th to 20th	Night	39% 4 5% 17% 24% 11%	5900
	21st to end	Night	53% 4 4 13% 15% 10%	6490
February	1st to 10th	Night	47% 4 8% 11% 16% 13%	2545
	11th to 20th	Night	46% 5% 7% 13% 18% 11%	2286
	21st to end	Night	48% 5% 6% 14% 16% 11%	1815
March	1st to 10th	Night	49% 6% 7% 13% 15% 10%	4919
	11th to 20th	Night	43% 6% 7% 13% 16% 15%	4980
	21st to end	Night	44% 6% 8% 15% 19% 8%	5467
April	1st to 10th	Night	44% 7% 10% 16% 14% 9%	2200
	11th to 20th	Night	40% 5% 10% 17% 15% 13%	1998
	21st to end	Night	38% 8% 10% 21% 17% 6%	2000
May	1st to 10th	Night	53% 8% 11% 16% 9% 3	4506
	11th to 20th	Night	39% 8% 12% 21% 16% 3	4054
	21st to end	Night	42% 13% 18% 21% 6% 1	4452
June	1st to 10th	Night	21% 8% 23% 31% 17%	1800
	11th to 20th	Night	22% 7% 20% 31% 17% 3	1800
	21st to end	Night	30% 11% 23% 26% 10%	1800
July	1st to 10th	Night	30% 9% 36% 23% 2	4035
	11th to 20th	Night	28% 10% 31% 27% 4	4026
	21st to end	Night	34% 11% 21% 29% 5%	4320
August	1st to 10th	Night	10% 7% 20% 48% 14%	2916
	11th to 20th	Night	14% 9% 37% 35% 4	3127
	21st to end	Night	28% 15% 21% 26% 9% 1	3586
September	1st to 10th	Night	31% 11% 23% 19% 13% 4	2197
	11th to 20th	Night	35% 9% 16% 20% 16% 4	2178
	21st to end	Night	28% 8% 14% 22% 18% 10%	2090
October	1st to 10th	Night	17% 5% 9% 17% 16% 36%	3672
	11th to 20th	Night	15% 5% 6% 22% 33% 18%	3779
	21st to end	Night	20% 4 6% 15% 38% 16%	4120
November	1st to 10th	Night	32% 6% 11% 22% 20% 10%	2340
	11th to 20th	Night	33% 5% 10% 19% 20% 13%	2400
	21st to end	Night	40% 5% 8% 20% 18% 10%	2415
December	1st to 10th	Night	52% 4 7% 15% 16% 6%	4250
	11th to 20th	Night	42% 6% 9% 11% 19% 13%	4817
	21st to end	Night	39% 6% 7% 13% 27% 8%	6490

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	25% 10% 35% 22% 8% 1	300
	11th to 20th	Day	21% 14% 30% 27% 7% 2	300
	21st to end	Day	20% 15% 31% 25% 9%	330
February	1st to 10th	Day	21% 14% 34% 25% 7%	300
	11th to 20th	Day	27% 17% 28% 21% 6% 1	300
	21st to end	Day	22% 16% 39% 19% 4	249
March	1st to 10th	Day	27% 15% 30% 23% 5%	300
	11th to 20th	Day	15% 17% 44% 17% 4 2	300
	21st to end	Day	18% 17% 32% 23% 9% 1	330
April	1st to 10th	Day	19% 16% 32% 24% 8% 1	300
	11th to 20th	Day	20% 13% 29% 24% 12% 1	467
	21st to end	Day	16% 7% 31% 29% 16% 1	500
May	1st to 10th	Day	14% 10% 30% 30% 16% 1	503
	11th to 20th	Day	11% 5% 29% 32% 20% 3	721
	21st to end	Day	10% 4 25% 37% 20% 3	789
June	1st to 10th	Day	7% 2 12% 35% 32% 12%	730
	11th to 20th	Day	7% 3 11% 37% 30% 13%	730
	21st to end	Day	7% 2 9% 29% 33% 19%	730
July	1st to 10th	Day	7% 2 7% 24% 37% 22%	721
	11th to 20th	Day	5% 1 4 22% 40% 27%	718
	21st to end	Day	6% 2 5% 23% 40% 25%	794
August	1st to 10th	Day	2 1 3 21% 43% 30%	726
	11th to 20th	Day	3 1 2 15% 44% 36%	586
	21st to end	Day	10% 2 5% 16% 36% 31%	580
September	1st to 10th	Day	7% 3 8% 23% 33% 25%	330
	11th to 20th	Day	10% 2 6% 23% 36% 23%	324
	21st to end	Day	10% 1 5% 29% 36% 19%	300
October	1st to 10th	Day	7% 1 9% 36% 35% 12%	300
	11th to 20th	Day	8% 4 13% 37% 26% 11%	300
	21st to end	Day	17% 7% 22% 28% 20% 6%	330
November	1st to 10th	Day	14% 6% 20% 31% 23% 6%	300
	11th to 20th	Day	15% 6% 21% 39% 16% 3	300
	21st to end	Day	14% 16% 30% 23% 15% 3	300
December	1st to 10th	Day	21% 7% 29% 24% 14% 5%	300
	11th to 20th	Day	16% 12% 31% 29% 11% 1	300
	21st to end	Day	19% 9% 35% 25% 10% 2	330
January	1st to 10th	Night	22% 8% 29% 31% 9%	1000
	11th to 20th	Night	22% 9% 27% 34% 8% 1	1000
	21st to end	Night	22% 8% 27% 35% 7%	1100
February	1st to 10th	Night	25% 8% 29% 32% 5%	945
	11th to 20th	Night	26% 10% 29% 29% 7%	732
	21st to end	Night	25% 10% 32% 27% 5%	495
March	1st to 10th	Night	24% 7% 30% 32% 7%	600
	11th to 20th	Night	19% 10% 28% 35% 9% 1	600
	21st to end	Night	17% 7% 29% 36% 11% 1	660
April	1st to 10th	Night	18% 8% 31% 37% 7%	600
	11th to 20th	Night	21% 9% 24% 35% 11%	593
	21st to end	Night	16% 7% 24% 39% 14% 1	600
May	1st to 10th	Night	16% 8% 24% 42% 10%	600
	11th to 20th	Night	12% 4 22% 41% 19% 2	591
	21st to end	Night	7% 4 19% 39% 28% 2	650
June	1st to 10th	Night	5% 1 6% 43% 40% 4	600
	11th to 20th	Night	6% 1 7% 40% 42% 4	600
	21st to end	Night	6% 1 9% 24% 52% 8%	600
July	1st to 10th	Night	5% 2 3 26% 53% 11%	585
	11th to 20th	Night	4 1 2 21% 60% 12%	582
	21st to end	Night	4 1 3 22% 60% 10%	657
August	1st to 10th	Night	2 1 2 15% 68% 12%	597
	11th to 20th	Night	4 1 2 15% 67% 11%	594
	21st to end	Night	5% 2 3 20% 56% 15%	660
September	1st to 10th	Night	7% 2 7% 22% 52% 11%	600
	11th to 20th	Night	13% 1 4 23% 51% 8%	594
	21st to end	Night	10% 1 6% 29% 46% 7%	570
October	1st to 10th	Night	6% 1 10% 35% 42% 7%	684
	11th to 20th	Night	9% 2 16% 40% 30% 3	760
	21st to end	Night	12% 5% 19% 36% 25% 3	836
November	1st to 10th	Night	12% 3 16% 40% 26% 3	780
	11th to 20th	Night	13% 6% 20% 41% 20% 1	800
	21st to end	Night	17% 6% 27% 34% 15% 1	815
December	1st to 10th	Night	20% 7% 25% 32% 16% 1	1000
	11th to 20th	Night	22% 8% 24% 35% 11% 1	1000
	21st to end	Night	20% 8% 29% 34% 9%	1100

Page generated at 2025-09-16 00:49:11. Version ac07

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