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 2024-03-23.

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% 3 5% 5% 3 5% 5% 6% 9% 40%	79222
	Night	13% 5% 2 5% 5% 3 4 4 5% 8% 46%	80715
Transparency	Day	38% 9% 13% 19% 14% 6%	78947
	Night	36% 7% 13% 20% 16% 8%	80510
Seeing	Day	12% 6% 19% 28% 25% 10%	13898
	Night	14% 5% 19% 30% 26% 6%	23908

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 5% 4 3 3 4 4 6% 39%	2847
	11th to 20th	Day	16% 6% 3 4 3 2 3 3 3 6% 51%	2850
	21st to end	Day	23% 8% 3 6% 5% 3 4 4 5% 7% 33%	3135
February	1st to 10th	Day	20% 8% 3 6% 5% 3 5% 5% 5% 6% 35%	1729
	11th to 20th	Day	22% 8% 4 6% 5% 2 2 4 3 5% 39%	1946
	21st to end	Day	22% 7% 3 6% 5% 3 4 4 3 6% 36%	1727
March	1st to 10th	Day	18% 8% 3 6% 5% 3 4 5% 5% 5% 38%	2090
	11th to 20th	Day	16% 7% 4 7% 6% 2 4 4 4 6% 40%	2090
	21st to end	Day	15% 6% 2 4 4 2 4 5% 6% 8% 45%	2200
April	1st to 10th	Day	15% 7% 4 6% 5% 3 6% 5% 5% 7% 39%	1992
	11th to 20th	Day	15% 7% 3 6% 5% 3 5% 4 5% 9% 38%	2134
	21st to end	Day	9% 6% 2 5% 4 3 5% 4 5% 8% 48%	2160
May	1st to 10th	Day	10% 5% 2 5% 6% 4 5% 6% 6% 9% 42%	2160
	11th to 20th	Day	10% 5% 2 5% 5% 3 5% 6% 6% 10% 43%	2226
	21st to end	Day	8% 5% 3 6% 6% 5% 7% 7% 8% 12% 35%	2531
June	1st to 10th	Day	6% 4 2 5% 5% 4 7% 7% 8% 12% 41%	2340
	11th to 20th	Day	5% 4 2 6% 6% 4 7% 7% 8% 12% 39%	2340
	21st to end	Day	8% 5% 3 6% 7% 4 8% 10% 9% 12% 29%	2340
July	1st to 10th	Day	10% 5% 3 5% 5% 4 7% 7% 10% 13% 31%	2340
	11th to 20th	Day	6% 4 2 5% 6% 4 8% 8% 8% 13% 36%	2340
	21st to end	Day	5% 4 2 5% 6% 4 7% 7% 9% 14% 37%	2546
August	1st to 10th	Day	3 3 2 4 4 4 7% 7% 11% 15% 40%	2328
	11th to 20th	Day	5% 3 2 5% 6% 4 7% 9% 10% 13% 35%	2138
	21st to end	Day	10% 5% 3 6% 7% 4 6% 8% 9% 11% 32%	2376
September	1st to 10th	Day	8% 5% 3 6% 6% 4 7% 7% 9% 10% 33%	2051
	11th to 20th	Day	15% 6% 3 6% 6% 4 5% 6% 6% 9% 34%	1980
	21st to end	Day	10% 4 2 5% 5% 4 4 5% 6% 9% 45%	1980
October	1st to 10th	Day	6% 4 2 4 4 3 4 5% 7% 8% 53%	1819
	11th to 20th	Day	10% 4 2 3 4 3 4 5% 7% 7% 52%	1800
	21st to end	Day	12% 4 2 5% 3 2 3 3 4 7% 54%	1980
November	1st to 10th	Day	10% 4 2 4 5% 4 4 4 5% 9% 48%	1858
	11th to 20th	Day	12% 5% 2 4 5% 4 5% 5% 5% 8% 46%	1900
	21st to end	Day	14% 8% 3 6% 4 2 4 4 4 6% 44%	1900
December	1st to 10th	Day	16% 6% 2 6% 5% 2 4 4 4 8% 43%	1753
	11th to 20th	Day	13% 7% 3 6% 6% 3 5% 5% 5% 6% 40%	2161
	21st to end	Day	16% 7% 2 5% 5% 3 4 4 4 7% 42%	3135
January	1st to 10th	Night	19% 8% 3 5% 4 2 4 4 4 6% 40%	4108
	11th to 20th	Night	17% 6% 2 5% 5% 2 3 3 3 6% 48%	4120
	21st to end	Night	25% 8% 3 5% 4 2 3 3 5% 8% 34%	4532
February	1st to 10th	Night	19% 8% 3 6% 5% 2 4 3 4 6% 39%	2466
	11th to 20th	Night	18% 8% 3 6% 4 2 3 3 4 6% 43%	2120
	21st to end	Night	20% 8% 3 5% 4 3 3 3 5% 6% 39%	1727
March	1st to 10th	Night	18% 8% 3 5% 5% 2 4 3 5% 7% 41%	2090
	11th to 20th	Night	15% 7% 3 5% 6% 2 4 5% 4 7% 41%	2090
	21st to end	Night	14% 6% 2 5% 4 2 4 4 4 6% 50%	2200
April	1st to 10th	Night	14% 6% 3 5% 5% 4 4 6% 5% 7% 41%	1967
	11th to 20th	Night	16% 5% 3 4 4 2 4 5% 5% 7% 46%	1775
	21st to end	Night	12% 5% 3 5% 4 3 5% 5% 6% 9% 44%	1800
May	1st to 10th	Night	12% 5% 3 4 5% 3 6% 5% 6% 10% 42%	1800
	11th to 20th	Night	8% 3 2 5% 6% 3 4 5% 6% 9% 49%	1664
	21st to end	Night	6% 4 2 3 4 4 5% 6% 6% 13% 45%	1745
June	1st to 10th	Night	4 3 1 3 3 2 5% 4 7% 11% 55%	1620
	11th to 20th	Night	6% 2 1 4 4 2 4 5% 7% 13% 50%	1620
	21st to end	Night	7% 5% 2 6% 5% 4 6% 6% 10% 12% 38%	1620
July	1st to 10th	Night	7% 5% 3 5% 5% 4 5% 6% 9% 11% 41%	1620
	11th to 20th	Night	3 2 1 3 6% 4 5% 6% 7% 12% 52%	1620
	21st to end	Night	4 2 2 4 4 2 6% 5% 8% 12% 50%	1772
August	1st to 10th	Night	2 1 1 2 3 2 3 5% 7% 13% 62%	1611
	11th to 20th	Night	3 3 2 4 5% 3 4 5% 8% 13% 49%	1759
	21st to end	Night	6% 4 2 5% 5% 3 5% 6% 8% 13% 43%	1980
September	1st to 10th	Night	7% 4 2 5% 5% 4 5% 5% 8% 12% 44%	1903
	11th to 20th	Night	11% 6% 3 6% 4 4 5% 6% 6% 9% 40%	1980
	21st to end	Night	8% 4 2 4 5% 2 4 5% 5% 8% 53%	1980
October	1st to 10th	Night	6% 4 2 3 4 2 5% 4 5% 8% 58%	2120
	11th to 20th	Night	9% 3 1 3 3 2 4 4 5% 7% 58%	2160
	21st to end	Night	11% 5% 2 3 3 2 3 3 4 5% 59%	2376
November	1st to 10th	Night	9% 5% 2 3 4 2 3 4 5% 7% 55%	2220
	11th to 20th	Night	11% 5% 2 4 4 2 4 4 4 6% 53%	2280
	21st to end	Night	13% 6% 3 5% 5% 3 4 4 4 5% 46%	2280
December	1st to 10th	Night	17% 6% 3 4 5% 3 3 4 5% 7% 42%	2422
	11th to 20th	Night	15% 7% 3 5% 5% 3 4 4 5% 6% 42%	3036
	21st to end	Night	17% 7% 3 5% 5% 3 5% 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	46% 9% 10% 14% 15% 5%	2090
	11th to 20th	Day	46% 7% 9% 12% 17% 8%	2090
	21st to end	Day	38% 6% 14% 16% 21% 5%	2200
April	1st to 10th	Day	43% 8% 10% 16% 14% 7%	1992
	11th to 20th	Day	43% 7% 11% 16% 14% 9%	2134
	21st to end	Day	34% 8% 13% 20% 20% 6%	2160
May	1st to 10th	Day	37% 9% 14% 17% 17% 6%	2160
	11th to 20th	Day	35% 9% 12% 27% 15% 3	2230
	21st to end	Day	37% 12% 16% 24% 10% 1	2531
June	1st to 10th	Day	31% 12% 18% 26% 13% 1	2340
	11th to 20th	Day	33% 10% 19% 26% 11% 1	2340
	21st to end	Day	40% 15% 18% 20% 7%	2340
July	1st to 10th	Day	37% 14% 24% 21% 4	2276
	11th to 20th	Day	34% 15% 25% 22% 5%	2271
	21st to end	Day	31% 16% 25% 24% 4 1	2405
August	1st to 10th	Day	24% 14% 26% 28% 8%	2314
	11th to 20th	Day	32% 18% 21% 24% 5% 1	2138
	21st to end	Day	40% 13% 20% 19% 5% 2	2376
September	1st to 10th	Day	38% 16% 16% 15% 13% 3	2051
	11th to 20th	Day	44% 11% 12% 18% 12% 2	1980
	21st to end	Day	34% 10% 15% 20% 14% 8%	1980
October	1st to 10th	Day	26% 7% 11% 26% 19% 10%	1819
	11th to 20th	Day	29% 6% 10% 20% 23% 12%	1800
	21st to end	Day	31% 5% 8% 16% 24% 15%	1980
November	1st to 10th	Day	32% 7% 11% 21% 20% 9%	1858
	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	42% 7% 12% 16% 15% 9%	2090
	11th to 20th	Night	43% 7% 12% 12% 17% 8%	2090
	21st to end	Night	36% 6% 12% 19% 20% 8%	2200
April	1st to 10th	Night	41% 8% 11% 16% 16% 9%	1967
	11th to 20th	Night	36% 6% 12% 19% 14% 12%	1775
	21st to end	Night	36% 7% 11% 19% 20% 7%	1800
May	1st to 10th	Night	37% 8% 12% 20% 15% 8%	1800
	11th to 20th	Night	31% 8% 12% 26% 19% 4	1665
	21st to end	Night	28% 10% 19% 28% 13% 2	1746
June	1st to 10th	Night	20% 10% 21% 33% 15%	1620
	11th to 20th	Night	24% 10% 19% 31% 15% 1	1620
	21st to end	Night	33% 10% 24% 24% 8%	1620
July	1st to 10th	Night	33% 11% 26% 25% 4	1575
	11th to 20th	Night	24% 12% 32% 27% 6%	1566
	21st to end	Night	24% 12% 31% 30% 4	1673
August	1st to 10th	Night	14% 9% 32% 37% 8%	1601
	11th to 20th	Night	24% 12% 28% 30% 5%	1759
	21st to end	Night	31% 12% 24% 24% 7% 2	1980
September	1st to 10th	Night	30% 11% 23% 20% 13% 3	1903
	11th to 20th	Night	39% 10% 16% 18% 14% 4	1980
	21st to end	Night	30% 8% 14% 22% 19% 7%	1980
October	1st to 10th	Night	24% 7% 11% 27% 19% 12%	2120
	11th to 20th	Night	24% 6% 10% 25% 20% 13%	2160
	21st to end	Night	27% 5% 8% 16% 25% 18%	2376
November	1st to 10th	Night	29% 6% 12% 22% 21% 10%	2220
	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% 14% 6%	270
	21st to end	Day	17% 16% 35% 26% 6%	270
April	1st to 10th	Day	15% 14% 38% 26% 7%	252
	11th to 20th	Day	18% 14% 28% 24% 15%	412
	21st to end	Day	12% 7% 33% 33% 14% 2	420
May	1st to 10th	Day	12% 9% 31% 28% 20% 1	423
	11th to 20th	Day	11% 3 21% 44% 18% 3	549
	21st to end	Day	8% 3 19% 43% 24% 4	679
June	1st to 10th	Day	7% 1 11% 37% 33% 11%	630
	11th to 20th	Day	6% 1 11% 38% 31% 12%	630
	21st to end	Day	10% 2 9% 29% 35% 15%	630
July	1st to 10th	Day	7% 2 5% 27% 41% 19%	621
	11th to 20th	Day	7% 1 2 25% 43% 23%	618
	21st to end	Day	5% 1 4 27% 42% 21%	684
August	1st to 10th	Day	3 2 19% 50% 26%	626
	11th to 20th	Day	3 2 14% 50% 31%	452
	21st to end	Day	12% 1 6% 16% 37% 27%	495
September	1st to 10th	Day	9% 1 5% 22% 42% 21%	341
	11th to 20th	Day	12% 1 6% 21% 43% 17%	270
	21st to end	Day	12% 9% 26% 41% 12%	270
October	1st to 10th	Day	9% 7% 39% 36% 8%	270
	11th to 20th	Day	12% 3 15% 35% 27% 9%	270
	21st to end	Day	18% 8% 22% 30% 19% 3	297
November	1st to 10th	Day	12% 6% 17% 40% 21% 4	270
	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	15% 7% 27% 35% 16% 1	600
April	1st to 10th	Night	16% 5% 30% 36% 12%	540
	11th to 20th	Night	17% 10% 26% 34% 14%	533
	21st to end	Night	14% 6% 28% 37% 15% 1	540
May	1st to 10th	Night	13% 6% 25% 40% 15%	540
	11th to 20th	Night	9% 5% 20% 44% 22% 1	531
	21st to end	Night	4 4 17% 38% 33% 4	584
June	1st to 10th	Night	6% 1 4 34% 48% 7%	540
	11th to 20th	Night	6% 1 5% 34% 46% 8%	540
	21st to end	Night	8% 1 6% 22% 48% 15%	540
July	1st to 10th	Night	6% 2 4 20% 48% 20%	525
	11th to 20th	Night	3 2 14% 54% 27%	522
	21st to end	Night	4 1 2 16% 58% 19%	591
August	1st to 10th	Night	2 1 10% 62% 25%	537
	11th to 20th	Night	5% 2 8% 63% 22%	534
	21st to end	Night	8% 1 4 17% 49% 21%	594
September	1st to 10th	Night	7% 1 4 14% 53% 21%	540
	11th to 20th	Night	11% 2 6% 20% 50% 11%	540
	21st to end	Night	9% 1 6% 25% 49% 10%	540
October	1st to 10th	Night	6% 2 9% 29% 44% 10%	680
	11th to 20th	Night	9% 2 17% 35% 32% 5%	720
	21st to end	Night	12% 6% 18% 36% 25% 4	792
November	1st to 10th	Night	10% 3 16% 41% 25% 5%	740
	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

Page generated at 2024-03-19 22:31:04. Version ac07

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