Brazosport Planetarium
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Brazosport Planetarium clear sky chart from 2005-11-06 to 2024-12-24.

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% 5% 5% 5% 5% 7% 9% 38%	101400
	Night	13% 6% 2 6% 4 4 4 3 5% 8% 44%	98763
Transparency	Day	38% 9% 14% 20% 13% 6%	105100
	Night	36% 7% 13% 21% 16% 8%	103189
Seeing	Day	13% 5% 20% 29% 22% 10%	14881
	Night	15% 4 18% 31% 26% 5%	24802

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% 11% 2 6% 4 4 4 3 5% 5% 36%	2847
	11th to 20th	Day	14% 7% 2 4 3 3 3 3 4 7% 51%	2850
	21st to end	Day	24% 8% 3 6% 4 3 4 4 6% 6% 32%	3135
February	1st to 10th	Day	20% 8% 3 7% 4 4 5% 4 5% 6% 33%	1828
	11th to 20th	Day	22% 8% 3 6% 4 4 4 3 5% 6% 36%	1886
	21st to end	Day	19% 8% 3 6% 4 3 3 3 5% 7% 38%	1727
March	1st to 10th	Day	20% 8% 3 7% 4 5% 5% 4 6% 8% 30%	3436
	11th to 20th	Day	18% 8% 3 9% 6% 5% 5% 4 6% 7% 29%	3480
	21st to end	Day	16% 5% 2 6% 4 4 4 3 5% 6% 45%	3814
April	1st to 10th	Day	16% 8% 3 7% 4 3 4 4 6% 8% 37%	2090
	11th to 20th	Day	17% 7% 2 6% 5% 4 5% 3 7% 7% 37%	2198
	21st to end	Day	11% 6% 2 6% 5% 4 5% 4 6% 7% 43%	2280
May	1st to 10th	Day	18% 7% 3 7% 5% 5% 5% 5% 7% 7% 31%	3765
	11th to 20th	Day	15% 6% 2 7% 4 5% 4 4 6% 6% 39%	4081
	21st to end	Day	9% 5% 2 6% 5% 5% 6% 6% 9% 12% 35%	4477
June	1st to 10th	Day	5% 4 2 6% 5% 5% 6% 6% 8% 10% 43%	2470
	11th to 20th	Day	6% 4 1 6% 6% 6% 7% 6% 9% 11% 37%	2470
	21st to end	Day	8% 5% 2 5% 7% 8% 7% 6% 9% 13% 30%	2470
July	1st to 10th	Day	8% 6% 2 6% 6% 5% 6% 5% 9% 12% 34%	4120
	11th to 20th	Day	6% 6% 3 10% 8% 8% 8% 6% 9% 10% 24%	4120
	21st to end	Day	11% 8% 3 8% 7% 6% 6% 5% 8% 11% 28%	4465
August	1st to 10th	Day	2 2 1 3 3 4 5% 5% 8% 12% 55%	4104
	11th to 20th	Day	2 2 1 5% 4 5% 6% 6% 10% 15% 44%	3833
	21st to end	Day	6% 4 2 8% 5% 7% 7% 6% 9% 11% 35%	4057
September	1st to 10th	Day	9% 7% 3 7% 7% 6% 7% 6% 7% 8% 32%	2090
	11th to 20th	Day	13% 7% 3 7% 6% 6% 6% 4 8% 7% 31%	2090
	21st to end	Day	9% 5% 3 6% 4 6% 5% 4 6% 7% 45%	2090
October	1st to 10th	Day	5% 5% 2 5% 5% 5% 4 4 7% 8% 51%	1981
	11th to 20th	Day	10% 6% 2 6% 4 4 4 4 5% 7% 50%	1900
	21st to end	Day	11% 5% 2 5% 4 3 3 3 4 7% 54%	2090
November	1st to 10th	Day	9% 6% 2 6% 5% 6% 6% 5% 6% 9% 41%	1958
	11th to 20th	Day	15% 6% 2 4 5% 3 4 4 5% 6% 46%	2000
	21st to end	Day	16% 6% 3 7% 5% 4 4 4 6% 5% 40%	1985
December	1st to 10th	Day	18% 7% 2 6% 4 5% 4 4 5% 8% 38%	1800
	11th to 20th	Day	13% 7% 2 7% 4 5% 4 4 6% 8% 40%	2251
	21st to end	Day	16% 6% 3 5% 4 4 4 3 5% 7% 42%	3162
January	1st to 10th	Night	21% 9% 2 7% 4 5% 3 3 4 5% 37%	4108
	11th to 20th	Night	18% 7% 2 5% 3 3 3 2 4 6% 47%	4120
	21st to end	Night	24% 9% 3 6% 3 3 3 3 5% 8% 33%	4532
February	1st to 10th	Night	19% 9% 3 7% 4 4 4 3 4 7% 37%	2366
	11th to 20th	Night	19% 9% 3 5% 3 3 3 2 3 6% 43%	2180
	21st to end	Night	19% 8% 2 6% 5% 4 4 3 3 6% 39%	1727
March	1st to 10th	Night	25% 12% 3 6% 3 3 3 3 5% 6% 30%	3419
	11th to 20th	Night	23% 9% 3 7% 5% 5% 5% 3 5% 6% 29%	3480
	21st to end	Night	12% 5% 2 6% 4 3 4 3 4 6% 50%	3817
April	1st to 10th	Night	14% 8% 3 6% 5% 4 4 3 5% 7% 41%	2090
	11th to 20th	Night	17% 5% 2 5% 4 3 4 3 5% 7% 45%	1928
	21st to end	Night	12% 6% 2 5% 5% 4 5% 5% 5% 7% 43%	1900
May	1st to 10th	Night	27% 8% 2 6% 3 3 4 4 4 8% 30%	3113
	11th to 20th	Night	15% 7% 2 5% 4 4 4 4 5% 8% 44%	2823
	21st to end	Night	15% 7% 2 5% 4 4 3 5% 7% 12% 36%	3090
June	1st to 10th	Night	5% 4 1 5% 3 3 3 3 6% 12% 54%	1710
	11th to 20th	Night	5% 4 1 4 3 4 4 4 9% 12% 50%	1710
	21st to end	Night	6% 4 1 6% 6% 4 6% 4 8% 13% 42%	1710
July	1st to 10th	Night	6% 5% 1 5% 5% 4 4 4 6% 12% 48%	2850
	11th to 20th	Night	3 3 2 6% 5% 6% 7% 5% 9% 14% 40%	2850
	21st to end	Night	8% 5% 2 7% 6% 6% 4 5% 8% 11% 37%	3098
August	1st to 10th	Night	1 1 1 2 2 3 2 5% 9% 74%	2836
	11th to 20th	Night	2 2 1 3 3 3 4 3 7% 14% 56%	2983
	21st to end	Night	4 3 1 4 4 4 5% 5% 7% 12% 51%	3593
September	1st to 10th	Night	6% 5% 2 7% 5% 5% 4 5% 8% 12% 42%	2090
	11th to 20th	Night	11% 6% 2 7% 5% 4 5% 4 5% 8% 43%	2090
	21st to end	Night	8% 4 2 5% 4 4 3 4 6% 9% 52%	2090
October	1st to 10th	Night	5% 4 2 4 4 3 4 3 5% 8% 59%	2178
	11th to 20th	Night	8% 4 1 4 3 3 3 2 5% 6% 61%	2280
	21st to end	Night	9% 4 2 5% 3 3 4 3 3 5% 60%	2508
November	1st to 10th	Night	9% 5% 1 5% 4 4 4 4 5% 7% 52%	2340
	11th to 20th	Night	13% 5% 2 5% 4 4 4 3 5% 6% 50%	2400
	21st to end	Night	14% 6% 2 7% 4 4 5% 3 4 6% 46%	2410
December	1st to 10th	Night	18% 8% 2 5% 4 3 3 3 5% 8% 39%	2600
	11th to 20th	Night	15% 8% 3 7% 4 4 4 3 5% 7% 39%	3166
	21st to end	Night	15% 7% 3 8% 4 4 4 3 4 5% 43%	4578

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% 6% 5% 16% 16% 9%	2848
	11th to 20th	Day	34% 6% 7% 25% 17% 10%	2850
	21st to end	Day	52% 4 4 16% 17% 8%	3135
February	1st to 10th	Day	50% 6% 7% 14% 13% 10%	1828
	11th to 20th	Day	50% 5% 8% 14% 16% 8%	1896
	21st to end	Day	46% 7% 10% 15% 14% 8%	1727
March	1st to 10th	Day	50% 13% 11% 13% 10% 3	3436
	11th to 20th	Day	52% 10% 11% 11% 12% 5%	3480
	21st to end	Day	38% 6% 11% 20% 20% 5%	3814
April	1st to 10th	Day	44% 7% 11% 17% 14% 8%	2090
	11th to 20th	Day	43% 8% 11% 17% 14% 8%	2198
	21st to end	Day	37% 7% 12% 22% 17% 6%	2280
May	1st to 10th	Day	46% 12% 15% 15% 8% 3	3800
	11th to 20th	Day	41% 10% 10% 19% 16% 5%	4085
	21st to end	Day	35% 14% 13% 30% 6%	4489
June	1st to 10th	Day	29% 9% 18% 29% 16%	2470
	11th to 20th	Day	33% 10% 16% 28% 13% 1	2470
	21st to end	Day	37% 12% 18% 26% 6%	2470
July	1st to 10th	Day	35% 11% 32% 19% 3	4056
	11th to 20th	Day	47% 12% 22% 15% 4	4051
	21st to end	Day	45% 11% 21% 20% 2	4325
August	1st to 10th	Day	16% 8% 19% 47% 9%	4090
	11th to 20th	Day	23% 12% 37% 26% 3	3871
	21st to end	Day	37% 13% 18% 23% 9% 1	4056
September	1st to 10th	Day	43% 11% 14% 17% 12% 2	2090
	11th to 20th	Day	45% 10% 11% 18% 14% 1	2090
	21st to end	Day	36% 6% 13% 20% 18% 8%	2090
October	1st to 10th	Day	21% 6% 8% 15% 18% 32%	3293
	11th to 20th	Day	23% 5% 6% 23% 32% 11%	3140
	21st to end	Day	24% 4 6% 21% 34% 10%	3428
November	1st to 10th	Day	36% 7% 12% 19% 20% 6%	1958
	11th to 20th	Day	39% 5% 9% 17% 17% 13%	2000
	21st to end	Day	43% 5% 10% 17% 15% 10%	1985
December	1st to 10th	Day	43% 7% 10% 21% 14% 5%	1800
	11th to 20th	Day	40% 6% 10% 16% 18% 10%	2249
	21st to end	Day	42% 7% 8% 14% 19% 11%	3162
January	1st to 10th	Night	49% 6% 5% 12% 15% 13%	4108
	11th to 20th	Night	38% 4 7% 17% 23% 12%	4120
	21st to end	Night	50% 4 5% 14% 17% 9%	4532
February	1st to 10th	Night	48% 5% 8% 10% 16% 13%	2366
	11th to 20th	Night	43% 4 8% 16% 18% 12%	2180
	21st to end	Night	48% 5% 7% 14% 18% 9%	1727
March	1st to 10th	Night	53% 6% 11% 16% 9% 5%	3419
	11th to 20th	Night	54% 8% 11% 13% 10% 5%	3480
	21st to end	Night	34% 6% 11% 16% 26% 7%	3817
April	1st to 10th	Night	41% 6% 10% 18% 16% 8%	2090
	11th to 20th	Night	39% 6% 11% 19% 14% 13%	1928
	21st to end	Night	38% 6% 11% 21% 17% 7%	1900
May	1st to 10th	Night	50% 8% 13% 15% 10% 5%	3143
	11th to 20th	Night	37% 8% 12% 22% 15% 7%	2824
	21st to end	Night	37% 8% 19% 28% 8% 1	3099
June	1st to 10th	Night	24% 6% 20% 31% 19%	1710
	11th to 20th	Night	24% 8% 16% 33% 16% 2	1710
	21st to end	Night	31% 10% 24% 26% 9%	1710
July	1st to 10th	Night	30% 7% 33% 27% 3	2805
	11th to 20th	Night	32% 12% 31% 22% 4	2796
	21st to end	Night	39% 11% 26% 21% 2	2999
August	1st to 10th	Night	10% 6% 17% 53% 14%	2826
	11th to 20th	Night	19% 8% 37% 33% 4	3010
	21st to end	Night	25% 14% 25% 25% 10% 1	3593
September	1st to 10th	Night	33% 11% 22% 20% 11% 3	2090
	11th to 20th	Night	40% 7% 14% 22% 15% 2	2090
	21st to end	Night	30% 7% 14% 22% 19% 8%	2090
October	1st to 10th	Night	19% 5% 8% 17% 18% 32%	3633
	11th to 20th	Night	17% 4 8% 25% 31% 15%	3779
	21st to end	Night	19% 4 6% 20% 36% 15%	4120
November	1st to 10th	Night	32% 6% 12% 23% 20% 8%	2340
	11th to 20th	Night	35% 4 11% 19% 19% 11%	2400
	21st to end	Night	40% 5% 9% 20% 17% 9%	2410
December	1st to 10th	Night	43% 5% 9% 20% 14% 8%	2600
	11th to 20th	Night	44% 5% 9% 14% 14% 14%	3167
	21st to end	Night	44% 6% 5% 15% 22% 9%	4578

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% 9% 38% 22% 6% 2	270
	11th to 20th	Day	21% 11% 35% 26% 6% 1	270
	21st to end	Day	22% 12% 37% 22% 7%	297
February	1st to 10th	Day	26% 15% 34% 19% 6% 1	270
	11th to 20th	Day	27% 12% 33% 22% 6%	270
	21st to end	Day	23% 13% 46% 14% 3	225
March	1st to 10th	Day	22% 13% 41% 22% 3	270
	11th to 20th	Day	19% 14% 45% 18% 3 1	270
	21st to end	Day	19% 15% 39% 24% 3	297
April	1st to 10th	Day	21% 13% 39% 22% 5%	270
	11th to 20th	Day	22% 14% 29% 21% 12% 1	396
	21st to end	Day	16% 7% 35% 28% 13% 1	460
May	1st to 10th	Day	19% 5% 34% 28% 13% 1	463
	11th to 20th	Day	14% 3 30% 35% 14% 4	674
	21st to end	Day	8% 3 26% 42% 18% 3	734
June	1st to 10th	Day	7% 3 14% 42% 26% 9%	680
	11th to 20th	Day	9% 1 13% 43% 26% 9%	680
	21st to end	Day	9% 3 9% 36% 31% 13%	680
July	1st to 10th	Day	9% 2 5% 31% 33% 20%	671
	11th to 20th	Day	6% 2 2 30% 36% 24%	668
	21st to end	Day	7% 2 3 31% 38% 19%	739
August	1st to 10th	Day	3 2 2 25% 42% 26%	676
	11th to 20th	Day	4 1 18% 45% 31%	547
	21st to end	Day	10% 2 3 19% 39% 28%	468
September	1st to 10th	Day	13% 3 5% 25% 38% 16%	300
	11th to 20th	Day	11% 2 6% 28% 34% 20%	300
	21st to end	Day	10% 3 7% 31% 36% 14%	300
October	1st to 10th	Day	7% 2 11% 46% 26% 8%	300
	11th to 20th	Day	10% 2 16% 36% 27% 10%	300
	21st to end	Day	15% 6% 26% 32% 18% 3	330
November	1st to 10th	Day	13% 4 23% 39% 16% 5%	300
	11th to 20th	Day	20% 5% 25% 32% 14% 3	300
	21st to end	Day	20% 9% 37% 20% 12% 3	300
December	1st to 10th	Day	20% 6% 33% 26% 12% 3	300
	11th to 20th	Day	19% 10% 36% 24% 10% 1	300
	21st to end	Day	19% 8% 40% 20% 12% 2	306
January	1st to 10th	Night	23% 6% 28% 31% 11%	950
	11th to 20th	Night	22% 7% 27% 34% 9% 1	950
	21st to end	Night	22% 7% 30% 32% 8%	1045
February	1st to 10th	Night	25% 8% 28% 33% 7%	846
	11th to 20th	Night	23% 9% 26% 33% 9%	706
	21st to end	Night	22% 10% 33% 28% 6%	471
March	1st to 10th	Night	22% 6% 27% 34% 11% 1	570
	11th to 20th	Night	20% 5% 27% 39% 9% 1	570
	21st to end	Night	17% 5% 28% 36% 13% 1	627
April	1st to 10th	Night	17% 6% 31% 36% 11%	570
	11th to 20th	Night	20% 6% 26% 36% 12%	563
	21st to end	Night	16% 7% 26% 37% 14% 1	570
May	1st to 10th	Night	19% 3 27% 40% 11%	570
	11th to 20th	Night	11% 2 22% 44% 19% 2	561
	21st to end	Night	10% 3 17% 41% 27% 2	617
June	1st to 10th	Night	7% 1 5% 37% 45% 5%	570
	11th to 20th	Night	6% 1 5% 42% 41% 5%	570
	21st to end	Night	8% 1 6% 27% 45% 13%	570
July	1st to 10th	Night	7% 1 4 21% 53% 15%	555
	11th to 20th	Night	4 1 1 14% 58% 22%	552
	21st to end	Night	4 1 2 17% 60% 15%	624
August	1st to 10th	Night	1 1 12% 69% 17%	567
	11th to 20th	Night	5% 1 10% 66% 18%	564
	21st to end	Night	7% 1 1 16% 56% 18%	627
September	1st to 10th	Night	8% 1 3 15% 56% 17%	570
	11th to 20th	Night	15% 1 3 19% 50% 13%	570
	21st to end	Night	9% 1 5% 25% 52% 9%	570
October	1st to 10th	Night	6% 1 8% 36% 40% 10%	658
	11th to 20th	Night	9% 2 13% 41% 30% 5%	760
	21st to end	Night	11% 3 16% 39% 26% 4	836
November	1st to 10th	Night	12% 2 16% 39% 27% 4	780
	11th to 20th	Night	16% 4 19% 38% 21% 2	800
	21st to end	Night	17% 4 25% 34% 17% 2	810
December	1st to 10th	Night	21% 6% 22% 30% 18% 2	1000
	11th to 20th	Night	23% 6% 25% 34% 12%	1000
	21st to end	Night	20% 7% 28% 31% 12% 1	1063

Page generated at 2024-12-21 03:13:51. Version ac07

Copyright © 2024 Attilla Danko.