Anahuac Wildlife Refuge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Anahuac Wildlife Refuge clear sky chart from 2005-11-06 to 2025-07-06.

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 7% 5% 5% 5% 4 6% 8% 39%	119908
	Night	14% 7% 2 6% 4 4 4 3 5% 8% 43%	119069
Transparency	Day	39% 9% 13% 19% 15% 6%	123570
	Night	37% 7% 13% 19% 16% 8%	123537
Seeing	Day	12% 7% 20% 28% 24% 9%	15683
	Night	14% 6% 19% 30% 26% 6%	25522

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% 10% 3 8% 3 3 3 3 3 5% 39%	4077
	11th to 20th	Day	16% 7% 2 6% 4 4 3 3 3 5% 46%	4080
	21st to end	Day	25% 9% 3 7% 4 3 4 3 4 6% 32%	4488
February	1st to 10th	Day	19% 8% 3 8% 5% 4 4 4 5% 6% 34%	1820
	11th to 20th	Day	22% 9% 3 6% 4 3 3 3 3 5% 38%	2052
	21st to end	Day	22% 8% 3 7% 4 3 4 4 4 6% 36%	1815
March	1st to 10th	Day	18% 8% 3 8% 5% 4 5% 4 6% 7% 34%	4936
	11th to 20th	Day	15% 7% 3 7% 4 4 4 3 5% 6% 44%	4980
	21st to end	Day	17% 7% 3 6% 5% 4 4 3 5% 6% 40%	5462
April	1st to 10th	Day	14% 7% 3 7% 4 4 5% 4 5% 6% 39%	2214
	11th to 20th	Day	14% 7% 3 6% 5% 5% 4 4 6% 8% 38%	2374
	21st to end	Day	9% 6% 2 6% 4 4 4 3 6% 8% 46%	2400
May	1st to 10th	Day	17% 8% 3 9% 6% 6% 6% 5% 7% 7% 26%	5405
	11th to 20th	Day	10% 5% 2 7% 4 4 5% 4 6% 9% 44%	5674
	21st to end	Day	8% 6% 3 7% 6% 6% 7% 6% 9% 12% 31%	6434
June	1st to 10th	Day	6% 5% 1 6% 4 6% 6% 6% 8% 12% 41%	2600
	11th to 20th	Day	5% 4 2 7% 5% 5% 7% 6% 8% 12% 39%	2600
	21st to end	Day	7% 5% 2 6% 6% 6% 7% 8% 9% 12% 31%	2600
July	1st to 10th	Day	8% 6% 3 6% 5% 6% 8% 6% 10% 13% 29%	4186
	11th to 20th	Day	5% 7% 3 11% 8% 8% 8% 6% 8% 11% 25%	4120
	21st to end	Day	10% 8% 3 9% 6% 6% 6% 5% 8% 11% 28%	4465
August	1st to 10th	Day	2 2 1 3 3 4 5% 4 8% 12% 57%	4104
	11th to 20th	Day	3 2 1 4 4 4 6% 6% 9% 14% 48%	3742
	21st to end	Day	8% 5% 2 7% 6% 6% 6% 5% 8% 10% 36%	4180
September	1st to 10th	Day	9% 6% 3 8% 5% 5% 7% 5% 9% 10% 32%	2164
	11th to 20th	Day	14% 6% 3 7% 5% 5% 5% 5% 6% 9% 36%	2090
	21st to end	Day	10% 4 2 5% 4 4 4 4 7% 9% 46%	2090
October	1st to 10th	Day	6% 4 2 5% 3 4 4 3 7% 7% 54%	1920
	11th to 20th	Day	9% 4 2 4 3 4 4 4 7% 7% 54%	1900
	21st to end	Day	12% 5% 2 5% 3 3 3 3 4 7% 54%	2090
November	1st to 10th	Day	11% 6% 2 5% 5% 5% 4 3 5% 8% 46%	1958
	11th to 20th	Day	12% 5% 1 5% 4 5% 4 4 5% 8% 47%	2000
	21st to end	Day	14% 8% 3 7% 4 3 4 3 4 6% 45%	2000
December	1st to 10th	Day	20% 10% 2 7% 4 3 3 3 4 7% 37%	3009
	11th to 20th	Day	11% 7% 3 7% 5% 5% 5% 4 5% 7% 42%	3391
	21st to end	Day	14% 7% 2 6% 4 4 4 3 4 6% 46%	4488
January	1st to 10th	Night	19% 7% 3 6% 4 4 3 3 4 5% 42%	5888
	11th to 20th	Night	17% 8% 3 6% 4 3 3 3 4 5% 45%	5900
	21st to end	Night	28% 9% 3 6% 4 3 3 3 4 6% 31%	6490
February	1st to 10th	Night	19% 8% 3 7% 5% 3 3 3 5% 6% 39%	2595
	11th to 20th	Night	18% 9% 3 7% 4 3 2 3 4 5% 41%	2234
	21st to end	Night	20% 10% 3 6% 3 4 3 3 5% 5% 38%	1815
March	1st to 10th	Night	20% 10% 3 7% 4 3 4 2 5% 6% 37%	4919
	11th to 20th	Night	17% 9% 3 6% 4 3 3 3 3 5% 43%	4980
	21st to end	Night	17% 10% 3 6% 4 3 3 3 4 6% 42%	5467
April	1st to 10th	Night	15% 7% 2 6% 4 5% 4 4 5% 7% 41%	2185
	11th to 20th	Night	15% 6% 3 5% 3 3 4 4 5% 7% 46%	1975
	21st to end	Night	12% 5% 3 5% 4 4 4 4 7% 8% 44%	2000
May	1st to 10th	Night	23% 8% 3 7% 5% 4 4 4 6% 8% 28%	4490
	11th to 20th	Night	12% 5% 2 6% 5% 4 4 4 6% 8% 43%	4215
	21st to end	Night	13% 8% 2 7% 5% 5% 5% 4 8% 12% 32%	4443
June	1st to 10th	Night	4 4 1 3 3 4 4 4 7% 12% 55%	1800
	11th to 20th	Night	5% 3 1 5% 4 3 5% 4 8% 13% 50%	1800
	21st to end	Night	6% 5% 2 6% 4 5% 6% 5% 10% 12% 41%	1800
July	1st to 10th	Night	5% 6% 3 6% 4 5% 5% 4 7% 12% 44%	2895
	11th to 20th	Night	2 4 2 6% 7% 6% 7% 6% 9% 11% 39%	2850
	21st to end	Night	7% 6% 3 9% 5% 5% 5% 4 8% 11% 37%	3098
August	1st to 10th	Night	1 1 1 2 3 3 3 3 6% 11% 67%	2836
	11th to 20th	Night	2 2 1 4 3 3 3 4 8% 13% 58%	3083
	21st to end	Night	4 4 2 6% 4 5% 6% 5% 9% 13% 43%	3476
September	1st to 10th	Night	7% 5% 2 6% 4 5% 4 5% 8% 12% 43%	2009
	11th to 20th	Night	10% 7% 3 7% 3 5% 5% 4 6% 8% 41%	2090
	21st to end	Night	8% 4 2 5% 3 3 4 4 5% 7% 54%	2090
October	1st to 10th	Night	5% 4 1 4 3 4 4 3 5% 8% 59%	2238
	11th to 20th	Night	8% 3 1 3 3 3 4 3 5% 7% 59%	2280
	21st to end	Night	10% 5% 2 4 2 3 3 3 4 5% 60%	2508
November	1st to 10th	Night	9% 6% 2 5% 4 4 3 4 5% 7% 52%	2340
	11th to 20th	Night	11% 6% 1 5% 3 3 4 3 4 6% 54%	2400
	21st to end	Night	13% 6% 3 6% 4 4 4 3 5% 6% 46%	2400
December	1st to 10th	Night	22% 9% 4 7% 5% 4 3 3 5% 6% 32%	4174
	11th to 20th	Night	12% 7% 3 8% 5% 4 4 3 5% 6% 44%	4816
	21st to end	Night	15% 7% 3 6% 4 3 4 2 4 5% 47%	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	49% 5% 4 18% 18% 6%	4078
	11th to 20th	Day	39% 5% 8% 18% 21% 10%	4080
	21st to end	Day	53% 5% 4 14% 14% 11%	4488
February	1st to 10th	Day	49% 6% 6% 15% 14% 10%	1820
	11th to 20th	Day	49% 5% 8% 13% 16% 8%	2062
	21st to end	Day	50% 7% 9% 13% 14% 8%	1815
March	1st to 10th	Day	47% 10% 8% 13% 12% 10%	4936
	11th to 20th	Day	40% 8% 8% 11% 18% 15%	4980
	21st to end	Day	43% 7% 10% 18% 19% 2	5464
April	1st to 10th	Day	43% 8% 10% 15% 15% 9%	2214
	11th to 20th	Day	43% 7% 11% 16% 15% 9%	2374
	21st to end	Day	34% 8% 13% 21% 19% 5%	2400
May	1st to 10th	Day	50% 12% 12% 15% 9% 3	5440
	11th to 20th	Day	35% 8% 14% 21% 19% 3	5678
	21st to end	Day	36% 13% 18% 24% 7% 1	6447
June	1st to 10th	Day	30% 12% 18% 26% 13%	2600
	11th to 20th	Day	33% 10% 18% 25% 12% 1	2600
	21st to end	Day	37% 15% 19% 22% 7%	2600
July	1st to 10th	Day	38% 15% 26% 18% 2	4122
	11th to 20th	Day	47% 14% 20% 15% 4	4051
	21st to end	Day	46% 14% 19% 19% 2	4325
August	1st to 10th	Day	16% 9% 19% 41% 14%	4090
	11th to 20th	Day	21% 13% 37% 26% 3	3778
	21st to end	Day	39% 12% 17% 19% 12% 1	4179
September	1st to 10th	Day	40% 15% 15% 14% 13% 3	2164
	11th to 20th	Day	43% 11% 12% 19% 14% 2	2090
	21st to end	Day	32% 9% 14% 20% 14% 10%	2090
October	1st to 10th	Day	21% 5% 8% 16% 15% 35%	3193
	11th to 20th	Day	19% 5% 8% 19% 40% 10%	3140
	21st to end	Day	24% 5% 7% 16% 38% 10%	3428
November	1st to 10th	Day	34% 7% 12% 21% 19% 8%	1958
	11th to 20th	Day	34% 7% 11% 15% 20% 13%	2000
	21st to end	Day	41% 6% 9% 17% 19% 9%	2000
December	1st to 10th	Day	48% 4 8% 16% 19% 4	3009
	11th to 20th	Day	39% 9% 9% 16% 18% 10%	3389
	21st to end	Day	38% 6% 8% 16% 22% 10%	4488
January	1st to 10th	Night	42% 6% 6% 19% 18% 8%	5888
	11th to 20th	Night	41% 5% 5% 15% 23% 11%	5900
	21st to end	Night	54% 4 5% 12% 14% 11%	6490
February	1st to 10th	Night	47% 5% 8% 10% 19% 11%	2595
	11th to 20th	Night	45% 6% 7% 14% 18% 10%	2234
	21st to end	Night	47% 6% 7% 14% 16% 10%	1815
March	1st to 10th	Night	47% 7% 8% 13% 14% 11%	4919
	11th to 20th	Night	44% 7% 7% 12% 15% 16%	4980
	21st to end	Night	43% 7% 9% 15% 19% 7%	5467
April	1st to 10th	Night	41% 8% 10% 16% 15% 10%	2185
	11th to 20th	Night	36% 6% 12% 19% 15% 12%	1975
	21st to end	Night	35% 8% 12% 20% 19% 6%	2000
May	1st to 10th	Night	51% 9% 11% 18% 9% 3	4520
	11th to 20th	Night	36% 8% 13% 23% 16% 4	4216
	21st to end	Night	38% 13% 20% 22% 7% 1	4452
June	1st to 10th	Night	20% 10% 22% 34% 15%	1800
	11th to 20th	Night	23% 10% 20% 31% 15% 1	1800
	21st to end	Night	31% 10% 27% 25% 8%	1800
July	1st to 10th	Night	32% 9% 36% 21% 2	2850
	11th to 20th	Night	33% 12% 29% 22% 4	2796
	21st to end	Night	40% 13% 24% 20% 2	2999
August	1st to 10th	Night	11% 7% 21% 46% 15%	2826
	11th to 20th	Night	16% 8% 38% 34% 4	3113
	21st to end	Night	31% 14% 21% 23% 10% 1	3476
September	1st to 10th	Night	32% 11% 22% 19% 13% 3	2009
	11th to 20th	Night	38% 9% 15% 18% 16% 4	2090
	21st to end	Night	29% 8% 13% 22% 19% 9%	2090
October	1st to 10th	Night	18% 5% 8% 17% 16% 35%	3732
	11th to 20th	Night	15% 5% 7% 24% 31% 18%	3779
	21st to end	Night	19% 5% 7% 14% 39% 16%	4120
November	1st to 10th	Night	31% 6% 13% 21% 20% 9%	2340
	11th to 20th	Night	32% 5% 9% 19% 22% 12%	2400
	21st to end	Night	39% 5% 9% 20% 19% 8%	2400
December	1st to 10th	Night	53% 5% 7% 16% 15% 5%	4174
	11th to 20th	Night	40% 6% 8% 14% 18% 13%	4817
	21st to end	Night	39% 6% 7% 13% 26% 8%	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	26% 12% 36% 20% 5%	300
	11th to 20th	Day	17% 15% 35% 27% 6% 1	300
	21st to end	Day	19% 17% 35% 23% 5%	330
February	1st to 10th	Day	22% 15% 34% 23% 5%	300
	11th to 20th	Day	27% 14% 34% 21% 3	300
	21st to end	Day	20% 17% 42% 18% 3	249
March	1st to 10th	Day	20% 15% 40% 22% 3	300
	11th to 20th	Day	13% 18% 50% 13% 5%	300
	21st to end	Day	17% 17% 36% 24% 6% 1	330
April	1st to 10th	Day	16% 17% 35% 24% 7%	314
	11th to 20th	Day	17% 13% 33% 23% 13%	492
	21st to end	Day	12% 8% 34% 32% 13% 1	500
May	1st to 10th	Day	13% 10% 32% 27% 17% 1	503
	11th to 20th	Day	10% 5% 26% 41% 16% 3	641
	21st to end	Day	7% 4 24% 40% 21% 3	789
June	1st to 10th	Day	6% 2 15% 37% 31% 10%	730
	11th to 20th	Day	6% 2 14% 38% 30% 10%	730
	21st to end	Day	9% 1 10% 31% 35% 14%	730
July	1st to 10th	Day	7% 2 5% 26% 40% 20%	697
	11th to 20th	Day	6% 2 3 25% 42% 22%	668
	21st to end	Day	7% 1 4 28% 41% 20%	739
August	1st to 10th	Day	3 2 19% 50% 25%	676
	11th to 20th	Day	3 1 2 14% 49% 31%	492
	21st to end	Day	12% 2 6% 18% 36% 25%	539
September	1st to 10th	Day	10% 2 8% 22% 40% 19%	374
	11th to 20th	Day	11% 1 7% 23% 41% 17%	300
	21st to end	Day	11% 9% 28% 39% 12%	300
October	1st to 10th	Day	8% 1 7% 42% 33% 8%	300
	11th to 20th	Day	11% 2 16% 36% 27% 8%	300
	21st to end	Day	16% 8% 21% 32% 19% 5%	330
November	1st to 10th	Day	13% 6% 20% 38% 20% 3	300
	11th to 20th	Day	15% 5% 26% 39% 12% 2	300
	21st to end	Day	16% 14% 33% 24% 11% 3	300
December	1st to 10th	Day	17% 9% 32% 25% 12% 5%	300
	11th to 20th	Day	16% 14% 34% 27% 8%	300
	21st to end	Day	17% 13% 36% 25% 7% 1	330
January	1st to 10th	Night	22% 9% 31% 30% 9% 1	1000
	11th to 20th	Night	18% 9% 30% 33% 10%	1000
	21st to end	Night	22% 8% 28% 34% 7%	1100
February	1st to 10th	Night	23% 8% 29% 33% 6%	995
	11th to 20th	Night	23% 11% 28% 30% 8%	680
	21st to end	Night	22% 12% 33% 26% 6%	495
March	1st to 10th	Night	21% 9% 31% 30% 10%	600
	11th to 20th	Night	17% 10% 27% 37% 9% 1	600
	21st to end	Night	15% 8% 27% 34% 15%	660
April	1st to 10th	Night	16% 7% 30% 35% 11%	600
	11th to 20th	Night	17% 11% 26% 34% 13%	593
	21st to end	Night	14% 6% 28% 37% 15% 1	600
May	1st to 10th	Night	14% 7% 25% 39% 14%	600
	11th to 20th	Night	8% 6% 22% 42% 20% 1	591
	21st to end	Night	5% 5% 19% 37% 31% 4	650
June	1st to 10th	Night	5% 2 5% 34% 47% 6%	600
	11th to 20th	Night	6% 1 6% 34% 45% 8%	600
	21st to end	Night	7% 1 6% 23% 49% 15%	600
July	1st to 10th	Night	7% 1 4 19% 48% 20%	570
	11th to 20th	Night	3 2 14% 54% 27%	552
	21st to end	Night	4 1 3 15% 58% 19%	624
August	1st to 10th	Night	2 1 10% 61% 25%	567
	11th to 20th	Night	4 2 8% 64% 22%	564
	21st to end	Night	7% 1 5% 18% 49% 20%	627
September	1st to 10th	Night	7% 2 6% 14% 51% 20%	570
	11th to 20th	Night	11% 2 6% 20% 49% 11%	570
	21st to end	Night	9% 1 6% 25% 49% 9%	570
October	1st to 10th	Night	6% 2 9% 30% 43% 9%	718
	11th to 20th	Night	8% 2 16% 38% 31% 5%	760
	21st to end	Night	11% 6% 18% 36% 26% 4	836
November	1st to 10th	Night	10% 4 18% 40% 24% 4	780
	11th to 20th	Night	13% 6% 20% 40% 21% 1	800
	21st to end	Night	16% 7% 26% 34% 16% 2	800
December	1st to 10th	Night	19% 7% 24% 32% 16% 1	950
	11th to 20th	Night	19% 9% 27% 34% 12%	1000
	21st to end	Night	20% 9% 28% 32% 10%	1100

Page generated at 2025-07-03 00:30:11. Version ac07

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