College Station
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the College Station clear sky chart from 2005-11-06 to 2024-02-20.

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 5% 5% 3 5% 5% 5% 8% 44%	78822
	Night	12% 5% 2 4 4 2 4 4 5% 7% 50%	80420
Transparency	Day	37% 7% 11% 19% 18% 7%	78547
	Night	33% 6% 12% 20% 19% 10%	80215
Seeing	Day	13% 6% 19% 26% 26% 10%	13898
	Night	14% 6% 25% 35% 18% 2	23960

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	16% 8% 2 4 3 2 4 4 5% 6% 45%	2847
	11th to 20th	Day	18% 6% 2 4 3 2 3 3 4 6% 50%	2850
	21st to end	Day	22% 9% 3 6% 3 1 2 3 4 7% 38%	3135
February	1st to 10th	Day	21% 9% 3 6% 4 2 3 4 4 6% 38%	1857
	11th to 20th	Day	21% 8% 2 3 5% 4 3 3 4 6% 41%	1839
	21st to end	Day	21% 7% 2 5% 4 3 3 4 3 5% 43%	1567
March	1st to 10th	Day	20% 7% 4 6% 5% 3 4 4 5% 6% 37%	1980
	11th to 20th	Day	17% 7% 3 5% 5% 3 4 4 4 5% 41%	1980
	21st to end	Day	15% 7% 3 5% 4 3 4 4 4 6% 44%	2178
April	1st to 10th	Day	13% 9% 3 6% 6% 2 5% 5% 5% 7% 39%	1980
	11th to 20th	Day	14% 7% 3 6% 6% 3 4 4 5% 7% 40%	2044
	21st to end	Day	13% 5% 3 6% 4 3 4 4 5% 8% 45%	2160
May	1st to 10th	Day	12% 6% 3 6% 6% 3 5% 5% 6% 8% 40%	2334
	11th to 20th	Day	12% 6% 2 5% 6% 4 5% 5% 6% 8% 41%	2302
	21st to end	Day	10% 5% 3 6% 7% 4 8% 7% 7% 9% 33%	2531
June	1st to 10th	Day	5% 4 2 4 5% 4 6% 7% 8% 10% 44%	2340
	11th to 20th	Day	4 3 2 4 5% 4 6% 6% 7% 11% 48%	2340
	21st to end	Day	5% 4 2 6% 7% 5% 8% 7% 8% 11% 37%	2340
July	1st to 10th	Day	9% 5% 3 6% 7% 5% 7% 6% 8% 10% 36%	2340
	11th to 20th	Day	4 2 2 5% 7% 4 6% 7% 9% 12% 42%	2340
	21st to end	Day	4 2 2 4 5% 4 6% 7% 8% 13% 44%	2546
August	1st to 10th	Day	3 2 1 3 4 4 5% 6% 7% 10% 55%	2328
	11th to 20th	Day	5% 2 2 4 5% 4 7% 6% 6% 11% 47%	2293
	21st to end	Day	5% 4 2 4 5% 4 7% 7% 8% 10% 43%	2240
September	1st to 10th	Day	6% 4 2 5% 6% 5% 6% 6% 7% 8% 45%	1980
	11th to 20th	Day	11% 5% 3 6% 6% 5% 5% 6% 6% 8% 40%	1980
	21st to end	Day	6% 3 2 4 6% 4 5% 7% 6% 7% 51%	1980
October	1st to 10th	Day	5% 4 2 5% 4 3 5% 4 5% 7% 58%	1922
	11th to 20th	Day	13% 5% 2 3 3 2 3 5% 4 6% 53%	1800
	21st to end	Day	14% 5% 2 4 3 2 3 3 4 4 58%	1980
November	1st to 10th	Day	11% 6% 3 4 4 3 5% 4 5% 7% 47%	1858
	11th to 20th	Day	11% 6% 3 5% 4 2 4 3 4 6% 52%	1900
	21st to end	Day	18% 7% 3 6% 5% 2 3 4 4 5% 42%	1725
December	1st to 10th	Day	15% 7% 3 6% 3 3 4 4 4 6% 45%	1710
	11th to 20th	Day	18% 6% 2 5% 5% 3 4 4 4 6% 42%	2161
	21st to end	Day	16% 8% 3 5% 4 2 4 3 3 5% 47%	3135
January	1st to 10th	Night	18% 6% 2 4 3 2 3 3 4 5% 50%	4108
	11th to 20th	Night	18% 5% 2 4 2 2 2 3 3 3 56%	4120
	21st to end	Night	22% 7% 3 5% 4 2 3 3 4 5% 41%	4532
February	1st to 10th	Night	20% 7% 3 6% 4 3 3 3 4 5% 44%	2337
	11th to 20th	Night	21% 7% 2 4 3 2 4 3 3 5% 47%	2212
	21st to end	Night	22% 5% 2 4 4 2 3 4 4 6% 43%	1687
March	1st to 10th	Night	17% 7% 2 5% 5% 2 4 4 4 8% 41%	1980
	11th to 20th	Night	15% 6% 3 5% 6% 3 4 4 5% 6% 43%	1980
	21st to end	Night	14% 6% 3 4 4 2 3 3 4 7% 51%	2178
April	1st to 10th	Night	12% 5% 2 5% 5% 3 5% 4 5% 8% 47%	1980
	11th to 20th	Night	12% 5% 2 5% 4 3 4 4 5% 8% 46%	1864
	21st to end	Night	13% 6% 2 5% 4 3 3 4 5% 7% 48%	1800
May	1st to 10th	Night	11% 6% 3 6% 5% 3 4 5% 5% 9% 45%	1621
	11th to 20th	Night	10% 5% 2 5% 4 2 3 4 6% 9% 50%	1593
	21st to end	Night	7% 5% 2 4 6% 3 4 4 7% 10% 47%	1745
June	1st to 10th	Night	4 3 2 3 3 2 4 3 7% 11% 56%	1620
	11th to 20th	Night	3 2 1 3 4 2 3 5% 6% 10% 62%	1620
	21st to end	Night	4 3 2 4 5% 4 5% 4 8% 11% 49%	1620
July	1st to 10th	Night	5% 3 2 4 5% 4 5% 5% 7% 10% 50%	1620
	11th to 20th	Night	2 2 1 3 3 2 4 5% 6% 12% 61%	1620
	21st to end	Night	3 2 1 3 3 3 5% 6% 8% 14% 52%	1772
August	1st to 10th	Night	2 1 1 1 3 2 3 4 6% 13% 66%	1611
	11th to 20th	Night	4 3 1 4 4 3 4 5% 6% 12% 52%	1604
	21st to end	Night	4 3 2 5% 5% 3 5% 6% 8% 12% 49%	2111
September	1st to 10th	Night	5% 5% 2 4 5% 3 4 6% 5% 10% 51%	1980
	11th to 20th	Night	9% 5% 3 5% 5% 4 5% 5% 5% 8% 46%	1980
	21st to end	Night	7% 3 2 4 3 2 4 4 5% 8% 57%	1980
October	1st to 10th	Night	4 3 2 4 4 3 4 3 4 7% 63%	2020
	11th to 20th	Night	12% 4 2 3 3 2 3 3 4 6% 59%	2160
	21st to end	Night	13% 5% 1 4 3 2 3 3 3 4 60%	2376
November	1st to 10th	Night	11% 5% 2 4 4 2 3 4 4 7% 56%	2220
	11th to 20th	Night	10% 6% 3 4 4 3 4 4 5% 7% 52%	2280
	21st to end	Night	17% 6% 3 4 4 2 4 4 4 6% 46%	2451
December	1st to 10th	Night	16% 8% 2 4 4 3 4 3 4 6% 46%	2470
	11th to 20th	Night	16% 8% 3 5% 4 3 4 3 4 6% 44%	3036
	21st to end	Night	16% 6% 2 4 4 2 3 3 3 5% 51%	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	37% 6% 7% 17% 22% 10%	2848
	11th to 20th	Day	36% 3 7% 19% 28% 6%	2850
	21st to end	Day	48% 4 4 13% 20% 11%	3135
February	1st to 10th	Day	48% 5% 6% 12% 18% 11%	1857
	11th to 20th	Day	47% 4 7% 15% 18% 10%	1849
	21st to end	Day	44% 5% 8% 14% 16% 13%	1567
March	1st to 10th	Day	47% 6% 8% 12% 20% 6%	1980
	11th to 20th	Day	45% 5% 8% 12% 20% 10%	1980
	21st to end	Day	42% 4 7% 17% 21% 8%	2178
April	1st to 10th	Day	45% 7% 7% 17% 15% 9%	1980
	11th to 20th	Day	43% 6% 9% 15% 18% 10%	2044
	21st to end	Day	38% 6% 10% 18% 22% 7%	2160
May	1st to 10th	Day	41% 8% 9% 17% 17% 8%	2334
	11th to 20th	Day	38% 9% 11% 21% 18% 3	2306
	21st to end	Day	43% 10% 13% 21% 12% 2	2531
June	1st to 10th	Day	31% 10% 15% 27% 15% 2	2340
	11th to 20th	Day	28% 9% 17% 25% 17% 4	2340
	21st to end	Day	39% 10% 15% 23% 12% 2	2340
July	1st to 10th	Day	40% 10% 20% 22% 8% 1	2276
	11th to 20th	Day	29% 11% 21% 22% 16% 1	2271
	21st to end	Day	27% 12% 22% 28% 10% 1	2405
August	1st to 10th	Day	23% 9% 20% 33% 15% 1	2314
	11th to 20th	Day	28% 11% 19% 27% 11% 3	2293
	21st to end	Day	32% 11% 18% 23% 13% 2	2240
September	1st to 10th	Day	34% 10% 12% 22% 15% 7%	1980
	11th to 20th	Day	41% 10% 14% 15% 16% 5%	1980
	21st to end	Day	31% 8% 11% 20% 17% 12%	1980
October	1st to 10th	Day	26% 6% 11% 21% 23% 13%	1922
	11th to 20th	Day	33% 5% 7% 16% 22% 16%	1800
	21st to end	Day	31% 5% 6% 15% 25% 18%	1980
November	1st to 10th	Day	35% 7% 9% 18% 22% 10%	1858
	11th to 20th	Day	33% 5% 10% 17% 22% 12%	1900
	21st to end	Day	45% 5% 7% 14% 19% 10%	1725
December	1st to 10th	Day	40% 5% 10% 17% 19% 8%	1710
	11th to 20th	Day	43% 6% 7% 13% 22% 10%	2159
	21st to end	Day	40% 4 6% 13% 26% 10%	3135
January	1st to 10th	Night	36% 5% 7% 18% 21% 13%	4108
	11th to 20th	Night	34% 3 6% 17% 28% 12%	4120
	21st to end	Night	45% 5% 5% 14% 21% 10%	4532
February	1st to 10th	Night	44% 4 5% 12% 19% 15%	2337
	11th to 20th	Night	42% 4 6% 15% 19% 14%	2212
	21st to end	Night	45% 4 8% 13% 15% 16%	1687
March	1st to 10th	Night	41% 7% 10% 14% 20% 9%	1980
	11th to 20th	Night	42% 6% 9% 13% 20% 10%	1980
	21st to end	Night	35% 5% 11% 17% 20% 11%	2178
April	1st to 10th	Night	36% 7% 10% 18% 17% 12%	1980
	11th to 20th	Night	37% 6% 11% 16% 17% 13%	1864
	21st to end	Night	36% 6% 9% 20% 22% 7%	1800
May	1st to 10th	Night	37% 8% 11% 18% 18% 8%	1621
	11th to 20th	Night	31% 7% 14% 25% 20% 3	1594
	21st to end	Night	31% 8% 15% 29% 15% 2	1746
June	1st to 10th	Night	21% 7% 20% 30% 20% 2	1620
	11th to 20th	Night	17% 8% 19% 32% 19% 5%	1620
	21st to end	Night	27% 8% 19% 29% 16% 2	1620
July	1st to 10th	Night	26% 11% 24% 30% 10%	1575
	11th to 20th	Night	16% 9% 29% 31% 15% 1	1566
	21st to end	Night	17% 12% 29% 31% 10%	1673
August	1st to 10th	Night	10% 7% 27% 38% 16% 2	1601
	11th to 20th	Night	23% 11% 19% 33% 11% 2	1604
	21st to end	Night	25% 11% 23% 27% 11% 3	2111
September	1st to 10th	Night	26% 10% 19% 23% 15% 6%	1980
	11th to 20th	Night	35% 9% 16% 19% 15% 7%	1980
	21st to end	Night	25% 6% 16% 20% 20% 13%	1980
October	1st to 10th	Night	21% 5% 12% 25% 22% 15%	2020
	11th to 20th	Night	27% 5% 7% 18% 24% 18%	2160
	21st to end	Night	29% 4 7% 16% 21% 22%	2376
November	1st to 10th	Night	29% 6% 10% 21% 21% 12%	2220
	11th to 20th	Night	34% 5% 9% 19% 20% 13%	2280
	21st to end	Night	40% 4 9% 15% 19% 13%	2451
December	1st to 10th	Night	40% 5% 8% 20% 18% 10%	2470
	11th to 20th	Night	42% 5% 7% 11% 21% 14%	3037
	21st to end	Night	36% 5% 6% 14% 28% 10%	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	23% 13% 31% 24% 7% 2	270
	11th to 20th	Day	26% 11% 31% 23% 7% 2	270
	21st to end	Day	21% 15% 35% 20% 9%	297
February	1st to 10th	Day	27% 16% 32% 18% 7%	270
	11th to 20th	Day	28% 19% 29% 19% 5%	267
	21st to end	Day	27% 20% 36% 14% 3 1	198
March	1st to 10th	Day	25% 15% 34% 19% 7%	240
	11th to 20th	Day	19% 17% 38% 19% 6% 2	240
	21st to end	Day	18% 13% 41% 20% 9%	264
April	1st to 10th	Day	21% 13% 37% 24% 5%	240
	11th to 20th	Day	22% 13% 29% 23% 12% 1	322
	21st to end	Day	16% 11% 33% 27% 10% 2	420
May	1st to 10th	Day	15% 9% 34% 31% 11% 1	597
	11th to 20th	Day	12% 8% 26% 33% 17% 4	625
	21st to end	Day	11% 4 23% 37% 21% 4	679
June	1st to 10th	Day	6% 2 12% 36% 33% 11%	630
	11th to 20th	Day	7% 1 12% 41% 31% 8%	630
	21st to end	Day	7% 1 13% 26% 39% 14%	630
July	1st to 10th	Day	6% 3 8% 29% 40% 16%	621
	11th to 20th	Day	3 2 31% 43% 21%	618
	21st to end	Day	4 5% 22% 49% 20%	684
August	1st to 10th	Day	3 4 19% 54% 20%	626
	11th to 20th	Day	6% 2 20% 52% 19%	607
	21st to end	Day	8% 1 4 16% 36% 34%	359
September	1st to 10th	Day	5% 1 3 21% 38% 33%	270
	11th to 20th	Day	9% 7% 22% 39% 24%	270
	21st to end	Day	8% 2 7% 25% 38% 20%	270
October	1st to 10th	Day	4 1 14% 32% 37% 12%	270
	11th to 20th	Day	13% 4 21% 29% 23% 10%	270
	21st to end	Day	24% 10% 22% 19% 19% 5%	297
November	1st to 10th	Day	13% 6% 20% 34% 20% 6%	270
	11th to 20th	Day	16% 10% 23% 34% 14% 3	270
	21st to end	Day	23% 13% 29% 21% 11% 2	270
December	1st to 10th	Day	20% 8% 28% 26% 13% 6%	270
	11th to 20th	Day	25% 14% 30% 23% 7% 1	270
	21st to end	Day	22% 11% 33% 22% 10% 1	297
January	1st to 10th	Night	20% 10% 30% 33% 7%	950
	11th to 20th	Night	23% 10% 29% 29% 8%	950
	21st to end	Night	20% 10% 31% 32% 6%	1045
February	1st to 10th	Night	22% 13% 33% 27% 4	817
	11th to 20th	Night	26% 11% 32% 28% 3	742
	21st to end	Night	26% 13% 38% 21% 2	503
March	1st to 10th	Night	20% 11% 40% 26% 4	540
	11th to 20th	Night	17% 11% 38% 27% 7%	540
	21st to end	Night	14% 10% 43% 29% 5% 1	594
April	1st to 10th	Night	14% 10% 41% 31% 4	540
	11th to 20th	Night	14% 10% 35% 33% 7%	533
	21st to end	Night	15% 11% 38% 28% 9% 1	540
May	1st to 10th	Night	12% 10% 40% 31% 7% 1	540
	11th to 20th	Night	13% 4 31% 38% 14% 1	531
	21st to end	Night	8% 3 26% 45% 17% 1	584
June	1st to 10th	Night	6% 2 14% 48% 28% 3	540
	11th to 20th	Night	4 1 23% 49% 22% 2	540
	21st to end	Night	4 1 12% 45% 33% 5%	540
July	1st to 10th	Night	5% 2 6% 46% 35% 6%	525
	11th to 20th	Night	3 8% 48% 37% 4	522
	21st to end	Night	2 1 6% 50% 37% 4	591
August	1st to 10th	Night	1 4 51% 40% 3	537
	11th to 20th	Night	6% 4 46% 40% 5%	534
	21st to end	Night	5% 7% 34% 47% 7%	594
September	1st to 10th	Night	6% 1 8% 33% 44% 7%	540
	11th to 20th	Night	12% 1 5% 33% 43% 6%	540
	21st to end	Night	8% 1 11% 36% 38% 6%	540
October	1st to 10th	Night	5% 2 13% 44% 31% 6%	580
	11th to 20th	Night	13% 3 21% 39% 22% 1	720
	21st to end	Night	14% 7% 27% 30% 19% 2	792
November	1st to 10th	Night	13% 4 24% 38% 20% 1	740
	11th to 20th	Night	12% 8% 27% 38% 14% 1	760
	21st to end	Night	20% 8% 28% 29% 14% 1	931
December	1st to 10th	Night	21% 7% 28% 31% 13%	950
	11th to 20th	Night	23% 11% 28% 31% 7%	950
	21st to end	Night	21% 9% 30% 31% 9% 1	1045

Page generated at 2024-02-17 05:28:38. Version ac07

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