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 2024-05-10.

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% 3 6% 6% 3 5% 5% 6% 8% 39%	84011
	Night	14% 6% 2 5% 4 3 4 4 5% 7% 45%	85479
Transparency	Day	40% 9% 12% 18% 15% 6%	83736
	Night	37% 7% 13% 19% 16% 8%	85274
Seeing	Day	12% 6% 18% 26% 25% 13%	14082
	Night	15% 5% 19% 32% 25% 3	24085

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	20% 9% 2 5% 5% 2 4 4 4 5% 41%	2847
	11th to 20th	Day	16% 6% 2 4 3 2 2 3 3 6% 53%	2850
	21st to end	Day	24% 7% 3 6% 5% 2 3 4 5% 8% 33%	3135
February	1st to 10th	Day	23% 8% 3 6% 5% 2 5% 4 4 6% 34%	1776
	11th to 20th	Day	23% 8% 3 5% 4 3 4 4 4 6% 36%	1896
	21st to end	Day	21% 8% 2 6% 4 3 4 4 4 5% 39%	1727
March	1st to 10th	Day	20% 9% 3 8% 6% 3 5% 4 5% 7% 29%	3436
	11th to 20th	Day	19% 7% 4 8% 6% 5% 5% 6% 6% 6% 29%	3480
	21st to end	Day	18% 6% 2 5% 5% 3 4 4 5% 6% 42%	3814
April	1st to 10th	Day	16% 6% 3 7% 6% 3 5% 5% 6% 5% 38%	2090
	11th to 20th	Day	17% 7% 3 6% 6% 3 4 4 4 7% 39%	2230
	21st to end	Day	10% 6% 3 6% 6% 3 4 6% 6% 7% 43%	2280
May	1st to 10th	Day	11% 6% 3 7% 6% 4 6% 5% 6% 7% 39%	2268
	11th to 20th	Day	10% 5% 3 7% 6% 3 5% 6% 5% 9% 42%	2298
	21st to end	Day	8% 6% 3 6% 7% 5% 7% 7% 8% 12% 31%	2531
June	1st to 10th	Day	6% 4 2 6% 6% 3 7% 6% 8% 10% 42%	2340
	11th to 20th	Day	5% 3 2 5% 7% 4 7% 8% 9% 10% 39%	2340
	21st to end	Day	7% 5% 4 6% 8% 5% 10% 7% 8% 10% 29%	2340
July	1st to 10th	Day	10% 5% 3 5% 6% 5% 7% 9% 9% 13% 30%	2340
	11th to 20th	Day	5% 4 2 7% 6% 4 7% 8% 10% 12% 34%	2340
	21st to end	Day	5% 4 3 5% 7% 5% 8% 7% 9% 12% 35%	2546
August	1st to 10th	Day	3 3 2 4 6% 5% 6% 8% 10% 13% 41%	2328
	11th to 20th	Day	4 3 2 6% 7% 4 8% 7% 9% 12% 37%	2186
	21st to end	Day	9% 4 3 6% 6% 4 7% 7% 9% 10% 34%	2374
September	1st to 10th	Day	7% 5% 2 5% 7% 5% 7% 8% 9% 10% 35%	1980
	11th to 20th	Day	15% 6% 3 6% 6% 4 5% 6% 7% 7% 34%	1980
	21st to end	Day	10% 5% 2 5% 4 3 4 4 6% 8% 48%	1980
October	1st to 10th	Day	8% 4 2 4 4 2 4 4 6% 8% 54%	1854
	11th to 20th	Day	11% 4 2 5% 5% 3 4 4 5% 7% 51%	1800
	21st to end	Day	13% 5% 2 4 3 2 3 4 3 6% 54%	1980
November	1st to 10th	Day	10% 4 3 4 5% 4 5% 4 5% 7% 48%	1858
	11th to 20th	Day	11% 5% 3 6% 5% 3 5% 4 6% 5% 47%	1900
	21st to end	Day	17% 6% 3 6% 5% 4 4 4 5% 6% 41%	1881
December	1st to 10th	Day	16% 8% 3 5% 5% 3 4 4 5% 7% 40%	1710
	11th to 20th	Day	14% 6% 3 6% 6% 3 5% 5% 5% 6% 41%	2161
	21st to end	Day	17% 6% 2 4 4 3 4 4 5% 6% 44%	3135
January	1st to 10th	Night	20% 7% 2 5% 4 3 3 4 4 6% 40%	4108
	11th to 20th	Night	19% 7% 3 4 3 2 2 3 3 5% 50%	4120
	21st to end	Night	25% 8% 3 5% 4 2 3 3 5% 7% 35%	4532
February	1st to 10th	Night	21% 8% 3 6% 5% 2 3 3 4 6% 39%	2418
	11th to 20th	Night	21% 9% 3 4 4 2 3 3 4 6% 42%	2169
	21st to end	Night	24% 7% 2 5% 5% 2 3 3 4 5% 39%	1727
March	1st to 10th	Night	27% 11% 3 5% 4 3 3 4 5% 6% 29%	3419
	11th to 20th	Night	24% 9% 4 7% 5% 3 4 4 5% 6% 30%	3480
	21st to end	Night	14% 6% 2 6% 5% 4 4 4 4 5% 45%	3817
April	1st to 10th	Night	16% 6% 3 6% 5% 3 4 5% 6% 7% 39%	2090
	11th to 20th	Night	20% 6% 3 4 4 2 3 4 5% 6% 44%	1897
	21st to end	Night	15% 7% 2 5% 5% 2 4 4 6% 6% 44%	1900
May	1st to 10th	Night	13% 6% 2 5% 5% 3 4 5% 6% 8% 41%	1894
	11th to 20th	Night	10% 5% 2 5% 5% 3 4 6% 6% 7% 47%	1593
	21st to end	Night	7% 4 2 4 5% 3 6% 5% 7% 11% 45%	1745
June	1st to 10th	Night	5% 3 1 3 3 2 4 4 6% 11% 56%	1620
	11th to 20th	Night	6% 3 2 3 3 2 4 5% 7% 12% 54%	1620
	21st to end	Night	6% 4 2 5% 6% 3 6% 5% 9% 12% 43%	1620
July	1st to 10th	Night	6% 4 3 5% 5% 3 6% 6% 7% 12% 44%	1620
	11th to 20th	Night	3 3 1 3 4 3 5% 4 6% 12% 56%	1620
	21st to end	Night	3 2 2 4 4 2 5% 6% 7% 11% 52%	1772
August	1st to 10th	Night	2 1 1 2 3 2 3 3 6% 12% 65%	1611
	11th to 20th	Night	4 2 1 4 3 3 4 5% 7% 14% 53%	1714
	21st to end	Night	6% 3 2 4 5% 4 5% 5% 8% 12% 45%	1980
September	1st to 10th	Night	5% 4 3 5% 5% 3 5% 5% 7% 11% 48%	1977
	11th to 20th	Night	12% 6% 3 5% 4 3 4 5% 5% 9% 45%	1980
	21st to end	Night	9% 4 2 3 4 3 3 4 6% 7% 53%	1980
October	1st to 10th	Night	5% 3 2 4 4 2 3 4 5% 7% 60%	2088
	11th to 20th	Night	10% 3 1 3 3 2 3 3 5% 7% 58%	2160
	21st to end	Night	11% 4 2 3 3 2 3 3 4 4 59%	2376
November	1st to 10th	Night	10% 5% 1 3 4 3 3 3 5% 7% 55%	2220
	11th to 20th	Night	12% 4 2 4 4 3 4 4 5% 6% 51%	2280
	21st to end	Night	16% 6% 3 5% 5% 2 4 4 4 5% 46%	2294
December	1st to 10th	Night	18% 7% 3 5% 5% 3 4 4 4 6% 42%	2470
	11th to 20th	Night	16% 8% 3 5% 5% 3 4 4 4 6% 42%	3036
	21st to end	Night	16% 7% 2 5% 5% 3 4 4 4 6% 44%	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	46% 4 5% 16% 19% 9%	2848
	11th to 20th	Day	34% 5% 6% 24% 21% 10%	2850
	21st to end	Day	49% 4 4 16% 16% 10%	3135
February	1st to 10th	Day	51% 6% 6% 13% 15% 10%	1776
	11th to 20th	Day	50% 6% 6% 13% 17% 9%	1906
	21st to end	Day	48% 6% 8% 14% 14% 10%	1727
March	1st to 10th	Day	51% 10% 12% 12% 12% 4	3436
	11th to 20th	Day	51% 10% 9% 13% 13% 5%	3480
	21st to end	Day	41% 7% 9% 18% 21% 4	3814
April	1st to 10th	Day	45% 8% 8% 16% 14% 9%	2090
	11th to 20th	Day	45% 6% 9% 15% 16% 9%	2230
	21st to end	Day	37% 8% 11% 18% 20% 6%	2280
May	1st to 10th	Day	41% 9% 11% 16% 16% 7%	2268
	11th to 20th	Day	37% 9% 11% 23% 16% 3	2302
	21st to end	Day	41% 11% 15% 21% 11% 1	2531
June	1st to 10th	Day	33% 11% 16% 24% 15% 1	2340
	11th to 20th	Day	32% 11% 17% 26% 12% 2	2340
	21st to end	Day	43% 14% 17% 19% 7%	2340
July	1st to 10th	Day	38% 15% 22% 21% 5%	2276
	11th to 20th	Day	34% 15% 24% 21% 6%	2271
	21st to end	Day	34% 15% 23% 24% 4 1	2405
August	1st to 10th	Day	27% 14% 23% 27% 9%	2314
	11th to 20th	Day	34% 16% 20% 24% 6% 1	2186
	21st to end	Day	38% 16% 19% 19% 7% 2	2374
September	1st to 10th	Day	36% 15% 16% 17% 12% 4	1980
	11th to 20th	Day	44% 12% 12% 15% 14% 3	1980
	21st to end	Day	33% 8% 15% 19% 16% 9%	1980
October	1st to 10th	Day	26% 7% 11% 25% 18% 13%	1854
	11th to 20th	Day	32% 7% 8% 20% 20% 14%	1800
	21st to end	Day	32% 5% 6% 16% 24% 17%	1980
November	1st to 10th	Day	34% 7% 11% 19% 20% 9%	1858
	11th to 20th	Day	37% 6% 10% 14% 20% 12%	1900
	21st to end	Day	43% 6% 8% 15% 17% 11%	1881
December	1st to 10th	Day	43% 6% 10% 18% 16% 7%	1710
	11th to 20th	Day	42% 7% 9% 13% 20% 9%	2159
	21st to end	Day	40% 6% 7% 15% 20% 11%	3135
January	1st to 10th	Night	43% 6% 7% 16% 16% 12%	4108
	11th to 20th	Night	38% 5% 6% 16% 26% 10%	4120
	21st to end	Night	49% 4 5% 16% 17% 9%	4532
February	1st to 10th	Night	47% 4 9% 11% 16% 13%	2418
	11th to 20th	Night	45% 5% 7% 13% 18% 12%	2169
	21st to end	Night	48% 5% 6% 14% 16% 11%	1727
March	1st to 10th	Night	54% 7% 10% 13% 11% 5%	3419
	11th to 20th	Night	54% 8% 9% 13% 12% 4	3480
	21st to end	Night	38% 8% 10% 15% 22% 7%	3817
April	1st to 10th	Night	43% 7% 10% 16% 14% 9%	2090
	11th to 20th	Night	41% 5% 10% 16% 15% 13%	1897
	21st to end	Night	39% 8% 8% 21% 17% 7%	1900
May	1st to 10th	Night	39% 8% 13% 18% 14% 8%	1894
	11th to 20th	Night	34% 7% 12% 24% 19% 4	1594
	21st to end	Night	30% 11% 20% 27% 11% 1	1746
June	1st to 10th	Night	21% 8% 23% 30% 17%	1620
	11th to 20th	Night	22% 7% 19% 32% 17% 2	1620
	21st to end	Night	31% 11% 21% 26% 10%	1620
July	1st to 10th	Night	32% 11% 26% 26% 5%	1575
	11th to 20th	Night	21% 12% 30% 30% 7%	1566
	21st to end	Night	22% 12% 29% 31% 4	1673
August	1st to 10th	Night	12% 9% 31% 38% 9%	1601
	11th to 20th	Night	20% 12% 30% 31% 6% 1	1714
	21st to end	Night	30% 12% 24% 26% 7% 2	1980
September	1st to 10th	Night	29% 11% 25% 20% 13% 3	1977
	11th to 20th	Night	36% 9% 16% 19% 15% 4	1980
	21st to end	Night	29% 8% 14% 22% 19% 8%	1980
October	1st to 10th	Night	23% 6% 13% 27% 19% 12%	2088
	11th to 20th	Night	25% 7% 10% 24% 22% 13%	2160
	21st to end	Night	28% 4 8% 16% 24% 20%	2376
November	1st to 10th	Night	29% 6% 11% 22% 21% 10%	2220
	11th to 20th	Night	34% 5% 11% 20% 20% 11%	2280
	21st to end	Night	41% 5% 8% 19% 18% 9%	2294
December	1st to 10th	Night	43% 5% 10% 19% 14% 9%	2470
	11th to 20th	Night	43% 5% 8% 11% 18% 14%	3037
	21st to end	Night	41% 6% 7% 13% 25% 7%	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	24% 8% 35% 24% 9% 1	270
	11th to 20th	Day	20% 13% 29% 29% 7% 2	270
	21st to end	Day	17% 15% 31% 27% 10%	297
February	1st to 10th	Day	22% 13% 35% 23% 7%	270
	11th to 20th	Day	26% 17% 29% 21% 7% 1	270
	21st to end	Day	20% 16% 42% 19% 2	225
March	1st to 10th	Day	27% 12% 32% 23% 6%	270
	11th to 20th	Day	17% 14% 44% 19% 4 2	270
	21st to end	Day	19% 16% 31% 24% 9% 1	297
April	1st to 10th	Day	18% 15% 34% 24% 9%	270
	11th to 20th	Day	21% 12% 29% 23% 13% 2	428
	21st to end	Day	14% 7% 30% 30% 17% 2	460
May	1st to 10th	Day	12% 10% 29% 31% 17% 1	459
	11th to 20th	Day	11% 3 27% 33% 22% 3	621
	21st to end	Day	9% 3 21% 39% 23% 4	679
June	1st to 10th	Day	7% 2 10% 34% 33% 14%	630
	11th to 20th	Day	7% 1 10% 37% 31% 14%	630
	21st to end	Day	8% 2 9% 27% 33% 20%	630
July	1st to 10th	Day	7% 2 6% 24% 38% 23%	621
	11th to 20th	Day	5% 3 20% 41% 30%	618
	21st to end	Day	4 1 4 22% 42% 28%	684
August	1st to 10th	Day	3 3 20% 43% 31%	626
	11th to 20th	Day	4 1 2 13% 42% 38%	500
	21st to end	Day	10% 1 4 15% 34% 36%	493
September	1st to 10th	Day	7% 1 4 21% 37% 30%	270
	11th to 20th	Day	11% 1 7% 20% 37% 23%	270
	21st to end	Day	11% 1 5% 27% 36% 20%	270
October	1st to 10th	Day	7% 1 7% 34% 38% 13%	270
	11th to 20th	Day	9% 5% 13% 34% 27% 12%	270
	21st to end	Day	19% 7% 22% 27% 20% 5%	297
November	1st to 10th	Day	13% 4 18% 34% 25% 6%	270
	11th to 20th	Day	16% 5% 20% 39% 16% 4	270
	21st to end	Day	15% 16% 30% 23% 14% 2	270
December	1st to 10th	Day	18% 7% 28% 26% 15% 6%	270
	11th to 20th	Day	16% 12% 31% 30% 10% 1	270
	21st to end	Day	20% 9% 34% 26% 10% 2	297
January	1st to 10th	Night	22% 8% 29% 32% 9%	950
	11th to 20th	Night	21% 8% 27% 35% 8% 1	950
	21st to end	Night	22% 8% 27% 36% 8%	1045
February	1st to 10th	Night	25% 8% 30% 33% 5%	898
	11th to 20th	Night	25% 10% 29% 30% 7%	695
	21st to end	Night	25% 11% 33% 26% 4	471
March	1st to 10th	Night	24% 6% 30% 32% 7%	570
	11th to 20th	Night	19% 9% 27% 35% 9% 1	570
	21st to end	Night	16% 7% 30% 36% 11% 1	627
April	1st to 10th	Night	16% 8% 31% 37% 8%	570
	11th to 20th	Night	22% 8% 24% 35% 11%	563
	21st to end	Night	17% 7% 24% 38% 14% 1	570
May	1st to 10th	Night	15% 7% 24% 43% 10%	569
	11th to 20th	Night	11% 3 21% 43% 20% 2	531
	21st to end	Night	6% 3 17% 41% 30% 3	584
June	1st to 10th	Night	5% 1 5% 44% 41% 4	540
	11th to 20th	Night	6% 1 6% 40% 43% 4	540
	21st to end	Night	7% 1 9% 24% 51% 8%	540
July	1st to 10th	Night	5% 2 3 26% 53% 11%	525
	11th to 20th	Night	4 1 1 20% 60% 14%	522
	21st to end	Night	4 3 21% 62% 10%	591
August	1st to 10th	Night	2 1 2 16% 68% 12%	537
	11th to 20th	Night	5% 1 2 14% 67% 12%	534
	21st to end	Night	6% 1 3 19% 56% 15%	594
September	1st to 10th	Night	6% 1 5% 20% 55% 12%	540
	11th to 20th	Night	14% 1 4 22% 51% 8%	540
	21st to end	Night	11% 1 6% 27% 47% 8%	540
October	1st to 10th	Night	6% 1 9% 34% 42% 7%	648
	11th to 20th	Night	10% 2 16% 38% 31% 3	720
	21st to end	Night	13% 5% 19% 36% 24% 3	792
November	1st to 10th	Night	12% 2 16% 41% 27% 3	740
	11th to 20th	Night	13% 6% 20% 41% 20% 1	760
	21st to end	Night	18% 6% 27% 33% 16% 1	774
December	1st to 10th	Night	19% 7% 25% 32% 17% 1	950
	11th to 20th	Night	22% 8% 25% 35% 11%	950
	21st to end	Night	20% 8% 30% 33% 9%	1045

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