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 2025-04-11.

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% 4 4 4 4 5% 7% 44%	113998
	Night	14% 6% 2 5% 3 3 3 3 5% 7% 49%	114499
Transparency	Day	36% 7% 11% 19% 18% 9%	117730
	Night	34% 6% 11% 20% 20% 11%	118896
Seeing	Day	13% 7% 20% 26% 25% 10%	15387
	Night	14% 7% 25% 35% 18% 2	25426

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% 10% 3 5% 3 3 3 3 4 5% 44%	4077
	11th to 20th	Day	14% 5% 2 5% 3 3 3 3 5% 6% 51%	4080
	21st to end	Day	28% 10% 3 6% 2 2 2 2 3 5% 38%	4488
February	1st to 10th	Day	21% 9% 3 7% 3 3 3 3 4 5% 39%	1955
	11th to 20th	Day	21% 9% 3 5% 5% 4 3 2 3 6% 40%	1949
	21st to end	Day	20% 8% 2 6% 4 3 3 3 3 5% 43%	1747
March	1st to 10th	Day	15% 9% 3 7% 5% 4 4 3 5% 6% 41%	4936
	11th to 20th	Day	13% 6% 2 5% 4 4 4 3 4 6% 48%	4980
	21st to end	Day	17% 9% 2 7% 4 4 4 3 5% 6% 40%	5462
April	1st to 10th	Day	13% 10% 2 7% 5% 4 5% 3 5% 6% 39%	2200
	11th to 20th	Day	15% 8% 2 7% 5% 4 4 3 5% 6% 39%	2159
	21st to end	Day	12% 6% 3 7% 4 3 4 4 5% 8% 44%	2280
May	1st to 10th	Day	18% 9% 3 8% 5% 4 5% 4 6% 7% 30%	4076
	11th to 20th	Day	14% 6% 2 6% 4 4 5% 4 6% 7% 41%	4082
	21st to end	Day	9% 6% 2 7% 6% 6% 7% 6% 8% 10% 32%	4477
June	1st to 10th	Day	5% 5% 2 5% 5% 5% 6% 5% 8% 10% 44%	2470
	11th to 20th	Day	5% 4 2 4 5% 5% 5% 5% 7% 10% 48%	2470
	21st to end	Day	5% 5% 2 7% 6% 6% 7% 5% 9% 11% 38%	2470
July	1st to 10th	Day	8% 4 1 4 5% 5% 5% 4 7% 10% 47%	4120
	11th to 20th	Day	5% 5% 2 7% 5% 5% 5% 5% 8% 11% 42%	4120
	21st to end	Day	12% 7% 3 7% 5% 6% 5% 5% 7% 10% 33%	4465
August	1st to 10th	Day	2 2 2 2 3 3 3 5% 8% 69%	4104
	11th to 20th	Day	3 1 1 3 3 4 4 4 7% 12% 56%	4019
	21st to end	Day	5% 4 2 5% 5% 6% 6% 5% 8% 10% 45%	3932
September	1st to 10th	Day	5% 5% 2 7% 5% 6% 6% 5% 7% 8% 44%	2090
	11th to 20th	Day	11% 5% 3 7% 6% 6% 4 4 6% 7% 41%	2090
	21st to end	Day	6% 3 2 4 5% 5% 5% 5% 6% 7% 52%	2090
October	1st to 10th	Day	5% 4 2 5% 3 3 5% 3 5% 6% 59%	2028
	11th to 20th	Day	13% 5% 2 4 3 3 4 4 4 5% 55%	1900
	21st to end	Day	13% 5% 2 4 3 3 3 2 4 4 58%	2090
November	1st to 10th	Day	11% 7% 2 5% 4 4 4 3 6% 7% 46%	1958
	11th to 20th	Day	10% 6% 2 6% 4 3 4 2 4 6% 53%	2000
	21st to end	Day	18% 7% 2 6% 5% 3 3 3 5% 5% 43%	1815
December	1st to 10th	Day	22% 7% 2 5% 3 4 4 2 4 5% 42%	2940
	11th to 20th	Day	20% 7% 2 6% 4 3 3 3 5% 7% 40%	3391
	21st to end	Day	15% 7% 3 7% 3 4 4 2 3 5% 47%	4488
January	1st to 10th	Night	18% 7% 2 4 3 3 3 2 4 5% 50%	5888
	11th to 20th	Night	15% 5% 1 3 2 2 3 3 3 5% 57%	5900
	21st to end	Night	28% 7% 2 5% 3 3 2 3 3 4 38%	6490
February	1st to 10th	Night	20% 7% 2 6% 3 4 3 2 4 5% 44%	2460
	11th to 20th	Night	21% 8% 2 4 3 3 3 2 3 5% 45%	2338
	21st to end	Night	22% 6% 2 4 4 3 4 2 4 6% 43%	1881
March	1st to 10th	Night	17% 9% 3 6% 4 4 3 3 4 7% 41%	4919
	11th to 20th	Night	16% 6% 2 6% 4 3 4 2 4 5% 48%	4980
	21st to end	Night	18% 10% 2 6% 3 3 3 2 4 5% 43%	5467
April	1st to 10th	Night	13% 5% 2 6% 4 4 5% 3 5% 7% 46%	2200
	11th to 20th	Night	13% 6% 2 6% 4 4 3 3 6% 8% 45%	1974
	21st to end	Night	14% 7% 2 5% 4 4 3 3 5% 7% 47%	1900
May	1st to 10th	Night	20% 9% 3 7% 4 4 3 3 5% 8% 34%	2824
	11th to 20th	Night	11% 6% 2 7% 4 4 4 3 6% 7% 47%	2823
	21st to end	Night	10% 6% 2 7% 5% 4 5% 4 7% 9% 40%	3090
June	1st to 10th	Night	5% 3 2 4 3 3 3 3 8% 11% 56%	1710
	11th to 20th	Night	3 2 1 3 4 2 3 4 6% 11% 61%	1710
	21st to end	Night	4 4 2 4 5% 4 5% 4 8% 11% 50%	1710
July	1st to 10th	Night	4 3 1 4 4 5% 4 4 7% 12% 50%	2850
	11th to 20th	Night	3 4 2 5% 3 4 4 4 7% 11% 54%	2850
	21st to end	Night	10% 7% 3 7% 4 5% 5% 5% 7% 10% 39%	3098
August	1st to 10th	Night	1 1 1 2 2 2 2 5% 10% 74%	2836
	11th to 20th	Night	2 2 1 3 2 3 3 4 7% 12% 59%	2815
	21st to end	Night	3 3 1 5% 3 4 4 4 8% 12% 52%	3719
September	1st to 10th	Night	5% 6% 2 5% 4 5% 4 4 5% 9% 50%	2090
	11th to 20th	Night	9% 6% 2 6% 4 5% 5% 4 5% 7% 46%	2090
	21st to end	Night	6% 3 2 4 3 3 4 3 5% 8% 58%	2090
October	1st to 10th	Night	4 3 1 4 3 4 3 3 4 7% 64%	2133
	11th to 20th	Night	11% 4 1 4 3 3 2 2 4 5% 61%	2280
	21st to end	Night	12% 5% 1 4 3 3 2 3 3 4 61%	2508
November	1st to 10th	Night	12% 5% 2 5% 3 3 3 3 4 6% 54%	2340
	11th to 20th	Night	9% 6% 2 5% 3 4 4 3 5% 6% 53%	2400
	21st to end	Night	16% 6% 2 5% 4 3 3 3 4 6% 47%	2580
December	1st to 10th	Night	21% 9% 3 6% 3 3 3 2 4 6% 40%	4250
	11th to 20th	Night	18% 9% 3 6% 3 3 3 2 4 4 45%	4816
	21st to end	Night	16% 6% 2 4 3 3 3 2 3 5% 54%	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	42% 5% 6% 23% 17% 7%	4078
	11th to 20th	Day	35% 3 5% 19% 26% 11%	4080
	21st to end	Day	51% 3 3 11% 18% 15%	4488
February	1st to 10th	Day	47% 5% 6% 12% 18% 12%	1955
	11th to 20th	Day	48% 3 7% 16% 17% 9%	1959
	21st to end	Day	44% 5% 7% 15% 17% 12%	1747
March	1st to 10th	Day	42% 7% 7% 14% 19% 11%	4936
	11th to 20th	Day	36% 6% 7% 10% 18% 23%	4980
	21st to end	Day	44% 5% 9% 19% 17% 6%	5464
April	1st to 10th	Day	45% 7% 6% 16% 14% 11%	2200
	11th to 20th	Day	43% 7% 9% 14% 18% 9%	2159
	21st to end	Day	38% 6% 10% 18% 21% 6%	2280
May	1st to 10th	Day	48% 11% 12% 14% 10% 5%	4114
	11th to 20th	Day	39% 9% 10% 17% 23% 3	4086
	21st to end	Day	38% 13% 14% 25% 10% 1	4489
June	1st to 10th	Day	31% 10% 15% 27% 15% 2	2470
	11th to 20th	Day	28% 9% 17% 24% 17% 4	2470
	21st to end	Day	37% 10% 15% 24% 12% 2	2470
July	1st to 10th	Day	30% 7% 27% 31% 5%	4056
	11th to 20th	Day	33% 8% 18% 25% 14% 1	4051
	21st to end	Day	44% 9% 18% 22% 6%	4325
August	1st to 10th	Day	14% 5% 14% 40% 26% 1	4090
	11th to 20th	Day	19% 7% 30% 34% 9% 2	4058
	21st to end	Day	31% 11% 20% 23% 13% 1	3931
September	1st to 10th	Day	35% 10% 12% 21% 15% 7%	2090
	11th to 20th	Day	40% 9% 13% 15% 17% 5%	2090
	21st to end	Day	30% 8% 11% 20% 17% 14%	2090
October	1st to 10th	Day	15% 4 7% 12% 21% 41%	3366
	11th to 20th	Day	20% 4 6% 16% 34% 20%	3140
	21st to end	Day	24% 5% 5% 21% 31% 15%	3428
November	1st to 10th	Day	35% 7% 9% 17% 21% 10%	1958
	11th to 20th	Day	33% 5% 9% 17% 22% 14%	2000
	21st to end	Day	43% 5% 7% 16% 19% 10%	1815
December	1st to 10th	Day	45% 4 7% 16% 21% 7%	2940
	11th to 20th	Day	43% 5% 8% 12% 23% 10%	3389
	21st to end	Day	40% 4 6% 13% 28% 9%	4488
January	1st to 10th	Night	37% 4 6% 22% 22% 9%	5888
	11th to 20th	Night	31% 3 5% 19% 29% 13%	5900
	21st to end	Night	50% 3 4 11% 17% 14%	6490
February	1st to 10th	Night	44% 4 5% 11% 19% 16%	2460
	11th to 20th	Night	43% 4 6% 15% 18% 13%	2338
	21st to end	Night	44% 4 7% 13% 16% 15%	1881
March	1st to 10th	Night	42% 6% 8% 13% 21% 10%	4919
	11th to 20th	Night	39% 5% 7% 14% 14% 22%	4980
	21st to end	Night	44% 5% 7% 16% 19% 9%	5467
April	1st to 10th	Night	36% 7% 10% 17% 17% 13%	2200
	11th to 20th	Night	37% 6% 11% 16% 17% 13%	1974
	21st to end	Night	36% 6% 10% 19% 22% 7%	1900
May	1st to 10th	Night	46% 9% 11% 18% 11% 5%	2851
	11th to 20th	Night	34% 8% 12% 20% 21% 4	2824
	21st to end	Night	35% 11% 15% 26% 12% 1	3099
June	1st to 10th	Night	21% 8% 20% 29% 21% 2	1710
	11th to 20th	Night	18% 8% 18% 32% 19% 5%	1710
	21st to end	Night	27% 7% 19% 29% 16% 2	1710
July	1st to 10th	Night	26% 8% 29% 32% 5%	2805
	11th to 20th	Night	24% 8% 21% 33% 13%	2796
	21st to end	Night	38% 9% 23% 23% 7%	2999
August	1st to 10th	Night	8% 5% 16% 41% 27% 2	2826
	11th to 20th	Night	17% 7% 30% 35% 11% 1	2842
	21st to end	Night	24% 11% 23% 28% 13% 2	3719
September	1st to 10th	Night	27% 10% 19% 22% 15% 7%	2090
	11th to 20th	Night	35% 9% 15% 19% 16% 7%	2090
	21st to end	Night	24% 6% 15% 20% 20% 14%	2090
October	1st to 10th	Night	13% 4 7% 15% 18% 42%	3562
	11th to 20th	Night	16% 3 4 20% 32% 25%	3779
	21st to end	Night	21% 3 5% 21% 32% 18%	4120
November	1st to 10th	Night	31% 6% 10% 20% 21% 12%	2340
	11th to 20th	Night	33% 5% 9% 18% 20% 15%	2400
	21st to end	Night	38% 4 9% 16% 19% 13%	2580
December	1st to 10th	Night	47% 4 5% 17% 21% 7%	4250
	11th to 20th	Night	44% 4 8% 8% 23% 14%	4817
	21st to end	Night	35% 4 5% 15% 30% 11%	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	23% 13% 31% 24% 7% 2	300
	11th to 20th	Day	25% 13% 31% 23% 7% 2	300
	21st to end	Day	24% 14% 35% 18% 8%	330
February	1st to 10th	Day	26% 15% 32% 20% 7%	300
	11th to 20th	Day	30% 17% 30% 18% 5%	300
	21st to end	Day	28% 18% 35% 13% 5%	249
March	1st to 10th	Day	22% 17% 35% 18% 7%	300
	11th to 20th	Day	17% 18% 41% 17% 5% 1	300
	21st to end	Day	19% 13% 40% 19% 9%	330
April	1st to 10th	Day	21% 15% 36% 22% 5%	300
	11th to 20th	Day	22% 14% 30% 22% 11% 1	357
	21st to end	Day	17% 11% 33% 27% 10% 2	460
May	1st to 10th	Day	15% 11% 35% 30% 10% 1	647
	11th to 20th	Day	13% 8% 26% 33% 16% 4	675
	21st to end	Day	11% 4 25% 36% 20% 4	734
June	1st to 10th	Day	5% 3 13% 36% 32% 11%	680
	11th to 20th	Day	7% 1 12% 41% 32% 8%	680
	21st to end	Day	7% 1 13% 26% 38% 15%	680
July	1st to 10th	Day	6% 2 8% 27% 40% 17%	671
	11th to 20th	Day	3 1 3 29% 43% 20%	668
	21st to end	Day	6% 1 5% 23% 47% 19%	739
August	1st to 10th	Day	3 4 18% 53% 22%	676
	11th to 20th	Day	6% 2 19% 52% 21%	656
	21st to end	Day	8% 2 4 17% 38% 32%	395
September	1st to 10th	Day	4 1 5% 24% 35% 30%	300
	11th to 20th	Day	8% 6% 23% 37% 26%	300
	21st to end	Day	7% 2 7% 26% 39% 20%	300
October	1st to 10th	Day	3 1 13% 33% 37% 13%	300
	11th to 20th	Day	12% 4 20% 31% 24% 9%	300
	21st to end	Day	22% 9% 21% 20% 20% 8%	330
November	1st to 10th	Day	14% 7% 21% 34% 19% 6%	300
	11th to 20th	Day	15% 10% 23% 32% 17% 3	300
	21st to end	Day	21% 13% 30% 21% 12% 3	300
December	1st to 10th	Day	21% 8% 29% 25% 12% 5%	300
	11th to 20th	Day	25% 13% 29% 24% 7% 2	300
	21st to end	Day	22% 12% 34% 22% 11% 1	330
January	1st to 10th	Night	20% 10% 30% 33% 7%	1000
	11th to 20th	Night	23% 11% 30% 29% 8%	1000
	21st to end	Night	21% 10% 31% 32% 6%	1100
February	1st to 10th	Night	22% 12% 34% 27% 4	860
	11th to 20th	Night	27% 11% 32% 27% 3	784
	21st to end	Night	26% 13% 37% 21% 3	561
March	1st to 10th	Night	21% 11% 40% 25% 4	600
	11th to 20th	Night	17% 12% 38% 26% 7%	600
	21st to end	Night	15% 10% 43% 28% 5%	660
April	1st to 10th	Night	16% 10% 40% 30% 4	600
	11th to 20th	Night	15% 11% 35% 32% 7%	565
	21st to end	Night	16% 11% 37% 28% 9% 1	570
May	1st to 10th	Night	12% 11% 40% 30% 6% 1	570
	11th to 20th	Night	13% 4 31% 38% 13% 1	561
	21st to end	Night	8% 4 28% 43% 16% 1	617
June	1st to 10th	Night	6% 2 15% 47% 27% 3	570
	11th to 20th	Night	3 1 22% 50% 22% 2	570
	21st to end	Night	4 1 12% 45% 33% 5%	570
July	1st to 10th	Night	4 2 6% 45% 37% 5%	555
	11th to 20th	Night	3 1 7% 47% 37% 4	552
	21st to end	Night	4 2 6% 49% 36% 4	624
August	1st to 10th	Night	1 1 4 50% 41% 3	567
	11th to 20th	Night	5% 4 46% 41% 4	564
	21st to end	Night	5% 7% 34% 48% 7%	627
September	1st to 10th	Night	6% 1 9% 34% 43% 7%	570
	11th to 20th	Night	12% 1 6% 34% 42% 5%	570
	21st to end	Night	7% 1 11% 36% 38% 5%	570
October	1st to 10th	Night	5% 2 12% 44% 31% 7%	613
	11th to 20th	Night	12% 3 21% 40% 22% 1	760
	21st to end	Night	13% 7% 26% 31% 19% 2	836
November	1st to 10th	Night	14% 4 24% 37% 20% 1	780
	11th to 20th	Night	12% 8% 26% 39% 15% 1	800
	21st to end	Night	19% 9% 29% 29% 14% 1	980
December	1st to 10th	Night	21% 7% 29% 30% 12%	1000
	11th to 20th	Night	23% 11% 28% 32% 7%	1000
	21st to end	Night	21% 8% 30% 32% 9% 1	1100

Page generated at 2025-04-08 08:17:25. Version ac07

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