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 2024-11-03.

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% 4 6% 9% 39%	100915
	Night	13% 6% 2 6% 4 4 4 4 6% 8% 44%	98126
Transparency	Day	39% 10% 14% 19% 13% 5%	100723
	Night	37% 8% 14% 20% 15% 7%	97989
Seeing	Day	12% 6% 19% 28% 25% 10%	14808
	Night	13% 5% 19% 30% 26% 6%	24615

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	19% 9% 3 6% 3 3 4 3 4 6% 39%	2847
	11th to 20th	Day	15% 7% 2 4 3 3 3 3 3 6% 51%	2850
	21st to end	Day	23% 8% 3 7% 4 3 4 3 5% 6% 33%	3135
February	1st to 10th	Day	20% 8% 3 7% 4 4 5% 4 5% 6% 34%	1729
	11th to 20th	Day	22% 9% 3 6% 4 3 3 3 3 5% 39%	1946
	21st to end	Day	21% 8% 3 7% 4 4 4 4 4 6% 36%	1727
March	1st to 10th	Day	20% 8% 4 8% 5% 5% 5% 4 7% 7% 27%	3436
	11th to 20th	Day	18% 8% 3 9% 6% 5% 5% 4 6% 6% 30%	3480
	21st to end	Day	16% 6% 2 5% 4 3 4 4 5% 6% 44%	3814
April	1st to 10th	Day	15% 7% 3 7% 4 4 5% 4 5% 7% 39%	2103
	11th to 20th	Day	14% 7% 3 6% 5% 5% 4 4 6% 8% 37%	2254
	21st to end	Day	9% 6% 2 5% 4 4 4 3 6% 8% 47%	2280
May	1st to 10th	Day	16% 8% 3 8% 7% 6% 6% 5% 7% 7% 28%	3765
	11th to 20th	Day	13% 6% 2 7% 4 4 4 3 5% 8% 44%	3950
	21st to end	Day	8% 5% 2 7% 6% 6% 7% 6% 9% 12% 32%	4477
June	1st to 10th	Day	6% 5% 1 6% 4 6% 6% 5% 8% 11% 41%	2470
	11th to 20th	Day	5% 4 2 7% 5% 5% 7% 6% 8% 12% 38%	2470
	21st to end	Day	8% 5% 2 6% 6% 6% 7% 8% 9% 12% 30%	2470
July	1st to 10th	Day	8% 6% 3 6% 6% 6% 8% 6% 10% 13% 29%	4120
	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	10% 5% 2 5% 5% 4 4 3 5% 9% 48%	1878
	11th to 20th	Day	12% 5% 1 5% 4 5% 4 4 5% 8% 46%	1900
	21st to end	Day	14% 8% 3 7% 4 3 4 3 4 6% 44%	1900
December	1st to 10th	Day	15% 7% 2 7% 4 3 4 3 4 8% 43%	1753
	11th to 20th	Day	13% 8% 3 7% 6% 4 5% 4 5% 6% 40%	2161
	21st to end	Day	15% 7% 2 6% 4 4 4 4 4 7% 42%	3135
January	1st to 10th	Night	19% 8% 3 6% 4 4 3 3 4 5% 40%	4108
	11th to 20th	Night	17% 7% 2 5% 4 3 3 2 3 6% 48%	4120
	21st to end	Night	25% 8% 3 6% 4 3 3 3 5% 7% 34%	4532
February	1st to 10th	Night	19% 8% 3 7% 5% 3 3 3 5% 6% 39%	2466
	11th to 20th	Night	18% 9% 3 6% 4 3 2 3 4 6% 42%	2120
	21st to end	Night	20% 9% 2 6% 3 4 3 3 5% 5% 39%	1727
March	1st to 10th	Night	24% 11% 3 7% 4 3 4 2 5% 6% 29%	3419
	11th to 20th	Night	21% 9% 3 7% 5% 4 4 4 4 6% 31%	3480
	21st to end	Night	12% 6% 2 6% 5% 4 4 4 5% 6% 46%	3817
April	1st to 10th	Night	14% 7% 2 6% 4 5% 4 5% 6% 7% 40%	2076
	11th to 20th	Night	16% 6% 3 5% 3 3 4 4 5% 7% 45%	1875
	21st to end	Night	13% 5% 3 5% 4 4 4 4 6% 8% 44%	1900
May	1st to 10th	Night	24% 8% 2 5% 5% 4 4 4 5% 8% 30%	3130
	11th to 20th	Night	13% 5% 2 7% 5% 5% 5% 4 6% 7% 43%	2933
	21st to end	Night	12% 7% 2 5% 4 5% 5% 4 8% 12% 36%	3090
June	1st to 10th	Night	4 4 1 3 2 4 4 4 7% 11% 56%	1710
	11th to 20th	Night	6% 3 1 5% 4 3 5% 4 8% 12% 50%	1710
	21st to end	Night	6% 5% 2 6% 4 5% 6% 5% 10% 12% 39%	1710
July	1st to 10th	Night	5% 5% 3 6% 4 4 5% 4 7% 11% 45%	2850
	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 4 3 3 3 4 5% 7% 54%	2245
	11th to 20th	Night	11% 6% 1 5% 3 4 4 3 5% 6% 53%	2280
	21st to end	Night	13% 6% 3 6% 4 4 4 3 5% 5% 46%	2280
December	1st to 10th	Night	17% 7% 3 5% 4 4 3 3 5% 6% 42%	2422
	11th to 20th	Night	15% 8% 3 5% 5% 4 4 3 5% 6% 42%	3036
	21st to end	Night	17% 7% 2 6% 4 4 4 3 4 6% 42%	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	46% 5% 5% 15% 20% 9%	2848
	11th to 20th	Day	34% 6% 9% 21% 20% 10%	2850
	21st to end	Day	51% 5% 5% 16% 14% 10%	3135
February	1st to 10th	Day	50% 6% 6% 15% 14% 10%	1729
	11th to 20th	Day	49% 5% 9% 13% 17% 9%	1956
	21st to end	Day	49% 6% 9% 13% 14% 8%	1727
March	1st to 10th	Day	52% 13% 10% 12% 10% 3	3436
	11th to 20th	Day	51% 10% 10% 11% 12% 5%	3480
	21st to end	Day	39% 7% 12% 17% 21% 3	3814
April	1st to 10th	Day	44% 8% 10% 16% 14% 8%	2103
	11th to 20th	Day	43% 7% 11% 15% 14% 9%	2254
	21st to end	Day	34% 8% 13% 20% 20% 5%	2280
May	1st to 10th	Day	49% 13% 12% 13% 9% 4	3800
	11th to 20th	Day	37% 8% 9% 21% 21% 4	3954
	21st to end	Day	36% 15% 17% 25% 7%	4489
June	1st to 10th	Day	31% 12% 18% 25% 13%	2470
	11th to 20th	Day	33% 10% 19% 25% 12% 1	2470
	21st to end	Day	38% 15% 19% 21% 7%	2470
July	1st to 10th	Day	38% 15% 26% 18% 2	4056
	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	26% 7% 11% 25% 19% 13%	1920
	11th to 20th	Day	28% 6% 10% 20% 25% 12%	1900
	21st to end	Day	31% 5% 8% 15% 26% 15%	2090
November	1st to 10th	Day	32% 8% 12% 21% 19% 9%	1878
	11th to 20th	Day	35% 7% 11% 15% 21% 11%	1900
	21st to end	Day	42% 5% 8% 17% 19% 9%	1900
December	1st to 10th	Day	40% 6% 11% 20% 15% 7%	1753
	11th to 20th	Day	42% 8% 10% 13% 18% 9%	2159
	21st to end	Day	40% 6% 9% 15% 21% 9%	3135
January	1st to 10th	Night	43% 6% 7% 16% 16% 11%	4108
	11th to 20th	Night	37% 6% 6% 15% 25% 11%	4120
	21st to end	Night	50% 4 6% 15% 16% 9%	4532
February	1st to 10th	Night	47% 5% 8% 10% 19% 11%	2466
	11th to 20th	Night	44% 6% 7% 14% 19% 10%	2120
	21st to end	Night	47% 6% 7% 14% 16% 10%	1727
March	1st to 10th	Night	52% 8% 11% 14% 10% 5%	3419
	11th to 20th	Night	53% 9% 10% 12% 12% 5%	3480
	21st to end	Night	36% 9% 11% 15% 23% 6%	3817
April	1st to 10th	Night	42% 8% 10% 16% 15% 9%	2076
	11th to 20th	Night	37% 7% 12% 18% 15% 12%	1875
	21st to end	Night	36% 7% 11% 20% 19% 6%	1900
May	1st to 10th	Night	51% 9% 11% 15% 9% 5%	3160
	11th to 20th	Night	38% 9% 10% 19% 19% 6%	2934
	21st to end	Night	34% 14% 20% 24% 8% 1	3099
June	1st to 10th	Night	20% 10% 21% 34% 15%	1710
	11th to 20th	Night	24% 9% 19% 30% 16% 2	1710
	21st to end	Night	32% 10% 25% 25% 8%	1710
July	1st to 10th	Night	31% 9% 36% 21% 2	2805
	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	23% 7% 10% 26% 19% 15%	2238
	11th to 20th	Night	23% 6% 10% 26% 21% 14%	2280
	21st to end	Night	26% 5% 8% 16% 27% 18%	2508
November	1st to 10th	Night	29% 6% 13% 22% 21% 10%	2245
	11th to 20th	Night	32% 6% 10% 20% 22% 10%	2280
	21st to end	Night	40% 5% 9% 20% 18% 8%	2280
December	1st to 10th	Night	42% 6% 10% 19% 14% 8%	2422
	11th to 20th	Night	42% 6% 8% 12% 18% 14%	3037
	21st to end	Night	42% 7% 8% 13% 22% 8%	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	26% 10% 37% 21% 6%	270
	11th to 20th	Day	15% 14% 35% 28% 7% 1	270
	21st to end	Day	18% 17% 35% 24% 5%	297
February	1st to 10th	Day	23% 16% 33% 23% 5%	270
	11th to 20th	Day	27% 13% 34% 22% 3	270
	21st to end	Day	19% 18% 45% 17% 1	225
March	1st to 10th	Day	20% 13% 42% 22% 3	270
	11th to 20th	Day	15% 16% 50% 13% 6%	270
	21st to end	Day	17% 16% 36% 25% 6%	297
April	1st to 10th	Day	16% 17% 36% 24% 6%	283
	11th to 20th	Day	18% 14% 31% 23% 14%	452
	21st to end	Day	12% 8% 34% 32% 14% 2	460
May	1st to 10th	Day	13% 11% 32% 26% 18% 1	463
	11th to 20th	Day	11% 5% 22% 43% 17% 3	595
	21st to end	Day	7% 3 22% 41% 22% 4	734
June	1st to 10th	Day	6% 2 13% 36% 32% 10%	680
	11th to 20th	Day	6% 2 13% 37% 30% 11%	680
	21st to end	Day	10% 1 10% 31% 34% 14%	680
July	1st to 10th	Day	7% 2 5% 26% 40% 20%	671
	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% 31% 19% 5%	330
November	1st to 10th	Day	12% 7% 17% 39% 21% 4	276
	11th to 20th	Day	16% 6% 26% 39% 11% 2	270
	21st to end	Day	17% 13% 32% 26% 10% 2	270
December	1st to 10th	Day	16% 7% 31% 27% 14% 5%	270
	11th to 20th	Day	17% 14% 33% 29% 6%	270
	21st to end	Day	18% 12% 37% 27% 6% 1	297
January	1st to 10th	Night	22% 8% 31% 30% 9% 1	950
	11th to 20th	Night	18% 8% 29% 34% 11%	950
	21st to end	Night	21% 8% 28% 35% 8%	1045
February	1st to 10th	Night	23% 8% 30% 33% 6%	946
	11th to 20th	Night	23% 10% 28% 31% 9%	646
	21st to end	Night	22% 13% 34% 25% 6%	471
March	1st to 10th	Night	21% 8% 31% 30% 10%	570
	11th to 20th	Night	17% 9% 27% 37% 9% 1	570
	21st to end	Night	14% 8% 28% 34% 15%	627
April	1st to 10th	Night	16% 6% 31% 36% 11%	570
	11th to 20th	Night	18% 10% 26% 33% 13%	563
	21st to end	Night	14% 6% 27% 36% 15% 1	570
May	1st to 10th	Night	14% 7% 25% 39% 14%	570
	11th to 20th	Night	9% 6% 20% 43% 21% 1	561
	21st to end	Night	4 4 19% 37% 32% 4	617
June	1st to 10th	Night	5% 2 5% 34% 48% 7%	570
	11th to 20th	Night	6% 1 5% 34% 46% 8%	570
	21st to end	Night	7% 1 6% 24% 48% 14%	570
July	1st to 10th	Night	6% 1 4 20% 48% 20%	555
	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% 3 16% 41% 25% 5%	749
	11th to 20th	Night	13% 5% 20% 39% 21% 1	760
	21st to end	Night	16% 7% 26% 34% 16% 2	760
December	1st to 10th	Night	19% 7% 23% 33% 17% 1	902
	11th to 20th	Night	19% 9% 27% 33% 11%	950
	21st to end	Night	21% 8% 28% 32% 10%	1045

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