Brazos Bend State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Brazos Bend State Park 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% 7% 2 7% 5% 5% 5% 4 6% 8% 39%	113898
	Night	14% 7% 2 6% 4 3 4 3 5% 7% 45%	114574
Transparency	Day	41% 6% 11% 19% 15% 7%	117601
	Night	38% 5% 12% 20% 17% 9%	119000
Seeing	Day	13% 7% 20% 27% 22% 11%	15246
	Night	15% 5% 20% 32% 24% 4	25270

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% 12% 3 6% 4 3 3 3 3 5% 37%	4077
	11th to 20th	Day	16% 6% 2 5% 3 3 3 2 4 7% 50%	4080
	21st to end	Day	28% 9% 3 6% 3 3 3 2 5% 6% 32%	4488
February	1st to 10th	Day	19% 10% 3 7% 4 4 4 3 5% 4 35%	1930
	11th to 20th	Day	22% 9% 3 6% 4 4 4 3 4 5% 37%	1964
	21st to end	Day	21% 9% 3 5% 4 4 4 3 4 6% 38%	1815
March	1st to 10th	Day	14% 7% 3 7% 5% 4 5% 4 6% 7% 38%	4936
	11th to 20th	Day	13% 6% 2 7% 5% 5% 4 3 4 5% 45%	4980
	21st to end	Day	16% 8% 3 7% 5% 4 4 3 5% 6% 40%	5462
April	1st to 10th	Day	14% 9% 3 7% 5% 4 5% 3 4 6% 39%	2200
	11th to 20th	Day	17% 8% 3 6% 5% 4 5% 3 4 7% 37%	2190
	21st to end	Day	9% 7% 3 8% 6% 5% 5% 4 5% 6% 42%	2280
May	1st to 10th	Day	16% 8% 3 7% 6% 5% 5% 4 6% 7% 33%	3829
	11th to 20th	Day	15% 6% 3 7% 5% 4 4 4 5% 7% 40%	4082
	21st to end	Day	8% 6% 2 7% 6% 5% 5% 5% 8% 10% 38%	4477
June	1st to 10th	Day	6% 4 2 6% 6% 6% 7% 6% 8% 9% 41%	2470
	11th to 20th	Day	5% 4 1 7% 6% 7% 6% 5% 9% 11% 38%	2470
	21st to end	Day	7% 5% 3 7% 7% 8% 9% 7% 9% 9% 29%	2470
July	1st to 10th	Day	8% 6% 2 6% 7% 8% 7% 6% 8% 11% 31%	4120
	11th to 20th	Day	6% 7% 3 11% 9% 8% 8% 6% 8% 10% 24%	4120
	21st to end	Day	14% 8% 3 8% 7% 7% 6% 6% 8% 9% 25%	4465
August	1st to 10th	Day	2 2 1 3 4 5% 6% 5% 8% 11% 54%	4104
	11th to 20th	Day	3 2 1 5% 5% 6% 7% 6% 10% 13% 43%	3883
	21st to end	Day	7% 5% 2 8% 7% 6% 6% 6% 8% 10% 35%	4029
September	1st to 10th	Day	8% 6% 3 9% 7% 7% 7% 5% 7% 7% 33%	2090
	11th to 20th	Day	13% 7% 3 9% 6% 6% 6% 5% 6% 9% 32%	2090
	21st to end	Day	9% 6% 2 5% 5% 5% 5% 4 6% 9% 43%	2090
October	1st to 10th	Day	6% 5% 2 4 4 4 4 4 7% 6% 53%	1990
	11th to 20th	Day	10% 6% 2 5% 3 4 4 3 6% 7% 50%	1900
	21st to end	Day	11% 4 2 5% 4 4 3 4 4 6% 52%	2090
November	1st to 10th	Day	10% 7% 2 8% 5% 4 5% 4 6% 9% 41%	1958
	11th to 20th	Day	13% 6% 3 6% 5% 5% 3 3 5% 7% 45%	2000
	21st to end	Day	15% 8% 3 7% 5% 4 4 3 5% 5% 40%	1950
December	1st to 10th	Day	25% 9% 3 6% 4 3 3 3 4 7% 34%	2940
	11th to 20th	Day	12% 7% 2 7% 4 4 4 4 5% 8% 43%	3391
	21st to end	Day	14% 6% 2 7% 3 4 4 4 5% 6% 45%	4488
January	1st to 10th	Night	21% 7% 3 6% 4 4 4 3 5% 5% 40%	5888
	11th to 20th	Night	15% 8% 2 6% 3 3 3 3 4 6% 48%	5900
	21st to end	Night	29% 8% 3 6% 3 3 3 3 4 6% 32%	6490
February	1st to 10th	Night	19% 9% 3 7% 4 3 4 3 4 6% 38%	2485
	11th to 20th	Night	20% 8% 3 6% 4 2 3 2 3 6% 43%	2321
	21st to end	Night	21% 9% 3 5% 4 4 3 3 4 4 40%	1815
March	1st to 10th	Night	21% 9% 3 6% 3 4 3 3 4 6% 37%	4919
	11th to 20th	Night	18% 8% 3 5% 4 4 3 3 4 5% 45%	4980
	21st to end	Night	18% 10% 2 5% 4 3 3 3 4 5% 42%	5467
April	1st to 10th	Night	15% 7% 2 7% 4 4 4 4 5% 7% 41%	2200
	11th to 20th	Night	19% 6% 2 6% 4 3 3 2 5% 6% 44%	1943
	21st to end	Night	14% 7% 2 7% 5% 5% 4 3 5% 7% 42%	1900
May	1st to 10th	Night	26% 9% 2 6% 4 4 4 3 5% 6% 31%	3051
	11th to 20th	Night	13% 7% 3 7% 4 4 4 4 6% 7% 42%	2823
	21st to end	Night	14% 8% 2 6% 4 4 4 4 8% 10% 35%	3090
June	1st to 10th	Night	4 3 2 4 3 3 3 2 6% 11% 57%	1710
	11th to 20th	Night	5% 3 2 3 3 3 3 4 7% 11% 56%	1710
	21st to end	Night	5% 3 2 5% 4 5% 5% 6% 7% 11% 46%	1710
July	1st to 10th	Night	6% 4 2 5% 4 4 4 4 6% 11% 50%	2850
	11th to 20th	Night	3 4 2 6% 5% 5% 6% 6% 8% 11% 44%	2850
	21st to end	Night	9% 6% 3 7% 5% 5% 6% 4 6% 10% 39%	3098
August	1st to 10th	Night	1 1 1 1 1 2 3 4 9% 76%	2836
	11th to 20th	Night	2 2 1 2 2 3 3 4 6% 16% 59%	2947
	21st to end	Night	4 3 2 5% 4 4 4 5% 7% 12% 51%	3622
September	1st to 10th	Night	5% 4 2 6% 5% 5% 5% 4 7% 10% 46%	2090
	11th to 20th	Night	10% 6% 3 7% 4 4 4 3 5% 8% 45%	2090
	21st to end	Night	7% 5% 2 5% 3 4 3 4 6% 8% 54%	2090
October	1st to 10th	Night	5% 4 1 5% 3 3 3 3 5% 8% 61%	2170
	11th to 20th	Night	9% 3 1 4 2 2 3 3 5% 6% 62%	2280
	21st to end	Night	10% 5% 1 4 3 3 3 3 4 4 61%	2508
November	1st to 10th	Night	10% 4 1 6% 4 4 4 4 6% 6% 52%	2340
	11th to 20th	Night	12% 5% 2 5% 3 3 4 4 4 6% 50%	2400
	21st to end	Night	14% 7% 2 6% 4 4 4 3 5% 5% 46%	2445
December	1st to 10th	Night	24% 11% 4 7% 4 4 3 2 4 6% 31%	4250
	11th to 20th	Night	14% 7% 3 7% 5% 4 4 4 4 5% 44%	4816
	21st to end	Night	15% 6% 2 6% 3 3 3 3 4 6% 48%	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	51% 3 5% 18% 17% 6%	4078
	11th to 20th	Day	37% 3 6% 23% 21% 10%	4080
	21st to end	Day	55% 2 3 12% 15% 12%	4488
February	1st to 10th	Day	51% 5% 6% 13% 14% 12%	1930
	11th to 20th	Day	51% 3 8% 13% 16% 8%	1974
	21st to end	Day	48% 4 8% 16% 15% 8%	1815
March	1st to 10th	Day	43% 5% 10% 18% 11% 13%	4936
	11th to 20th	Day	40% 6% 7% 9% 21% 17%	4980
	21st to end	Day	45% 3 8% 19% 20% 5%	5464
April	1st to 10th	Day	46% 6% 8% 17% 14% 9%	2200
	11th to 20th	Day	46% 5% 10% 16% 14% 9%	2190
	21st to end	Day	41% 6% 9% 19% 18% 6%	2280
May	1st to 10th	Day	48% 7% 11% 19% 10% 4	3864
	11th to 20th	Day	42% 8% 9% 17% 20% 5%	4086
	21st to end	Day	36% 9% 13% 33% 8% 1	4489
June	1st to 10th	Day	33% 9% 18% 24% 16% 1	2470
	11th to 20th	Day	35% 9% 13% 26% 15% 1	2470
	21st to end	Day	44% 11% 16% 21% 8%	2470
July	1st to 10th	Day	43% 6% 28% 20% 3	4056
	11th to 20th	Day	52% 8% 20% 16% 4	4051
	21st to end	Day	51% 10% 18% 20% 2	4325
August	1st to 10th	Day	22% 7% 15% 44% 12%	4090
	11th to 20th	Day	27% 8% 32% 27% 4	3922
	21st to end	Day	42% 8% 16% 22% 11% 1	4028
September	1st to 10th	Day	46% 10% 13% 15% 12% 3	2090
	11th to 20th	Day	47% 8% 12% 17% 13% 3	2090
	21st to end	Day	37% 7% 14% 16% 17% 10%	2090
October	1st to 10th	Day	23% 3 6% 16% 15% 37%	3302
	11th to 20th	Day	25% 3 6% 19% 35% 12%	3140
	21st to end	Day	29% 3 4 18% 34% 12%	3428
November	1st to 10th	Day	38% 5% 11% 19% 19% 8%	1958
	11th to 20th	Day	40% 4 8% 15% 19% 14%	2000
	21st to end	Day	45% 6% 8% 15% 16% 10%	1950
December	1st to 10th	Day	53% 3 7% 17% 17% 4	2940
	11th to 20th	Day	40% 3 7% 21% 19% 10%	3389
	21st to end	Day	40% 4 5% 18% 21% 12%	4488
January	1st to 10th	Night	48% 3 6% 17% 16% 10%	5888
	11th to 20th	Night	41% 2 4 19% 21% 12%	5900
	21st to end	Night	55% 2 4 12% 15% 11%	6490
February	1st to 10th	Night	48% 4 7% 10% 17% 13%	2485
	11th to 20th	Night	44% 4 7% 15% 17% 12%	2321
	21st to end	Night	48% 5% 6% 13% 19% 9%	1815
March	1st to 10th	Night	49% 4 7% 15% 14% 11%	4919
	11th to 20th	Night	43% 4 7% 13% 17% 16%	4980
	21st to end	Night	45% 4 8% 15% 21% 8%	5467
April	1st to 10th	Night	43% 5% 10% 18% 15% 10%	2200
	11th to 20th	Night	41% 4 10% 17% 14% 13%	1943
	21st to end	Night	42% 5% 9% 21% 16% 7%	1900
May	1st to 10th	Night	53% 7% 9% 16% 10% 5%	3081
	11th to 20th	Night	38% 7% 11% 21% 16% 7%	2824
	21st to end	Night	41% 10% 16% 26% 7% 1	3099
June	1st to 10th	Night	22% 7% 22% 30% 19% 1	1710
	11th to 20th	Night	23% 6% 19% 33% 17% 3	1710
	21st to end	Night	29% 10% 24% 26% 11%	1710
July	1st to 10th	Night	30% 5% 34% 27% 3	2805
	11th to 20th	Night	32% 7% 31% 24% 6%	2796
	21st to end	Night	40% 9% 26% 22% 3	2999
August	1st to 10th	Night	9% 4 19% 54% 14%	2826
	11th to 20th	Night	16% 6% 37% 36% 4 1	2974
	21st to end	Night	26% 11% 24% 28% 9% 1	3622
September	1st to 10th	Night	32% 9% 23% 20% 13% 4	2090
	11th to 20th	Night	37% 8% 14% 23% 15% 3	2090
	21st to end	Night	28% 6% 15% 23% 19% 9%	2090
October	1st to 10th	Night	18% 3 7% 18% 18% 36%	3625
	11th to 20th	Night	16% 3 7% 23% 34% 16%	3779
	21st to end	Night	21% 2 5% 19% 36% 17%	4120
November	1st to 10th	Night	30% 5% 13% 22% 21% 9%	2340
	11th to 20th	Night	34% 6% 10% 19% 19% 13%	2400
	21st to end	Night	40% 5% 9% 20% 17% 10%	2445
December	1st to 10th	Night	56% 3 6% 16% 14% 5%	4250
	11th to 20th	Night	42% 4 10% 13% 17% 14%	4817
	21st to end	Night	40% 3 6% 15% 26% 10%	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	29% 11% 33% 20% 5% 2	300
	11th to 20th	Day	25% 11% 32% 24% 6% 1	300
	21st to end	Day	22% 19% 30% 22% 8%	330
February	1st to 10th	Day	22% 16% 31% 24% 7%	300
	11th to 20th	Day	30% 12% 32% 20% 6% 1	300
	21st to end	Day	28% 13% 40% 16% 4	249
March	1st to 10th	Day	23% 17% 36% 17% 6%	300
	11th to 20th	Day	17% 18% 43% 17% 3 2	300
	21st to end	Day	19% 17% 33% 21% 9% 1	330
April	1st to 10th	Day	22% 19% 31% 21% 6%	300
	11th to 20th	Day	22% 15% 30% 21% 11% 1	388
	21st to end	Day	14% 10% 35% 26% 13% 2	460
May	1st to 10th	Day	18% 8% 32% 27% 14% 1	501
	11th to 20th	Day	13% 7% 28% 33% 15% 4	675
	21st to end	Day	10% 4 25% 39% 19% 3	734
June	1st to 10th	Day	6% 2 13% 35% 32% 11%	680
	11th to 20th	Day	6% 2 15% 36% 31% 10%	680
	21st to end	Day	9% 2 10% 30% 34% 16%	680
July	1st to 10th	Day	10% 1 6% 28% 33% 22%	671
	11th to 20th	Day	5% 1 3 30% 35% 27%	668
	21st to end	Day	8% 1 4 27% 36% 24%	739
August	1st to 10th	Day	3 1 3 25% 38% 29%	676
	11th to 20th	Day	4 1 2 17% 41% 34%	572
	21st to end	Day	9% 3 7% 16% 34% 31%	453
September	1st to 10th	Day	12% 1 8% 25% 32% 22%	300
	11th to 20th	Day	10% 2 9% 26% 30% 23%	300
	21st to end	Day	8% 1 8% 29% 36% 18%	300
October	1st to 10th	Day	8% 3 9% 40% 31% 9%	300
	11th to 20th	Day	9% 4 14% 38% 23% 11%	300
	21st to end	Day	18% 7% 25% 25% 19% 6%	330
November	1st to 10th	Day	16% 5% 23% 35% 17% 4	300
	11th to 20th	Day	17% 8% 25% 33% 13% 4	300
	21st to end	Day	16% 16% 33% 20% 11% 3	300
December	1st to 10th	Day	21% 7% 32% 25% 9% 6%	300
	11th to 20th	Day	17% 14% 35% 24% 8% 2	300
	21st to end	Day	18% 9% 39% 21% 9% 2	330
January	1st to 10th	Night	21% 9% 30% 31% 9%	1000
	11th to 20th	Night	20% 10% 28% 33% 8% 1	1000
	21st to end	Night	24% 8% 27% 34% 7%	1100
February	1st to 10th	Night	24% 9% 28% 32% 6%	885
	11th to 20th	Night	25% 10% 26% 31% 7%	767
	21st to end	Night	25% 11% 34% 25% 5%	495
March	1st to 10th	Night	24% 8% 30% 31% 7%	600
	11th to 20th	Night	19% 9% 31% 34% 8%	600
	21st to end	Night	19% 7% 29% 34% 10% 1	660
April	1st to 10th	Night	16% 9% 32% 36% 7%	600
	11th to 20th	Night	22% 10% 24% 34% 11%	565
	21st to end	Night	17% 8% 28% 35% 11%	570
May	1st to 10th	Night	17% 5% 30% 39% 9%	570
	11th to 20th	Night	11% 3 23% 46% 15% 1	561
	21st to end	Night	8% 5% 21% 42% 23% 1	617
June	1st to 10th	Night	4 2 8% 41% 42% 2	570
	11th to 20th	Night	5% 1 8% 46% 36% 4	570
	21st to end	Night	5% 1 10% 29% 46% 9%	570
July	1st to 10th	Night	7% 3 27% 51% 11%	555
	11th to 20th	Night	4 1 1 21% 61% 13%	552
	21st to end	Night	4 1 3 23% 57% 12%	624
August	1st to 10th	Night	1 1 1 21% 65% 11%	567
	11th to 20th	Night	4 1 18% 66% 11%	564
	21st to end	Night	6% 1 3 20% 55% 15%	627
September	1st to 10th	Night	6% 2 5% 19% 52% 15%	570
	11th to 20th	Night	12% 1 4 24% 48% 10%	570
	21st to end	Night	8% 1 6% 28% 49% 8%	570
October	1st to 10th	Night	6% 2 8% 35% 43% 7%	650
	11th to 20th	Night	9% 2 20% 39% 28% 3	760
	21st to end	Night	11% 6% 18% 38% 24% 3	836
November	1st to 10th	Night	12% 3 18% 39% 26% 2	780
	11th to 20th	Night	14% 5% 21% 40% 20% 1	800
	21st to end	Night	18% 8% 25% 33% 15% 2	845
December	1st to 10th	Night	22% 5% 25% 30% 17% 1	1000
	11th to 20th	Night	19% 8% 26% 35% 10% 1	1000
	21st to end	Night	22% 7% 29% 32% 9% 1	1100

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

Copyright © 2025 Attilla Danko.