Houma
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Houma clear sky chart from 2005-11-06 to 2025-10-04.

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	10% 6% 3 7% 5% 5% 6% 5% 7% 9% 37%	126179
	Night	10% 6% 2 6% 4 4 4 4 6% 8% 46%	123276
Transparency	Day	39% 9% 14% 18% 15% 6%	129826
	Night	33% 8% 15% 19% 17% 8%	127703
Seeing	Day	12% 7% 20% 25% 22% 14%	15874
	Night	11% 5% 18% 30% 26% 9%	25425

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	15% 5% 4 8% 5% 4 4 4 6% 9% 36%	4077
	11th to 20th	Day	14% 9% 3 6% 3 3 4 3 4 6% 47%	4080
	21st to end	Day	19% 9% 3 7% 4 5% 4 4 5% 7% 33%	4908
February	1st to 10th	Day	13% 8% 2 7% 5% 5% 5% 4 5% 6% 38%	2000
	11th to 20th	Day	14% 7% 2 6% 4 4 4 4 7% 8% 42%	1948
	21st to end	Day	16% 9% 3 6% 5% 4 4 3 5% 8% 37%	1650
March	1st to 10th	Day	17% 8% 3 7% 4 4 5% 3 5% 8% 35%	4887
	11th to 20th	Day	9% 5% 2 6% 4 4 5% 4 7% 9% 44%	4980
	21st to end	Day	13% 6% 3 7% 4 4 4 4 6% 7% 43%	5640
April	1st to 10th	Day	10% 6% 2 6% 5% 5% 5% 5% 6% 8% 43%	2400
	11th to 20th	Day	12% 7% 3 6% 4 4 5% 5% 6% 9% 40%	2374
	21st to end	Day	7% 5% 2 6% 5% 5% 5% 5% 5% 9% 46%	2400
May	1st to 10th	Day	12% 6% 3 7% 5% 5% 6% 5% 8% 10% 33%	5405
	11th to 20th	Day	6% 4 2 6% 4 5% 5% 4 7% 9% 47%	5404
	21st to end	Day	6% 4 2 6% 5% 5% 6% 5% 8% 11% 41%	5932
June	1st to 10th	Day	8% 7% 3 8% 7% 7% 7% 6% 8% 9% 29%	2400
	11th to 20th	Day	6% 6% 2 7% 7% 8% 9% 7% 9% 12% 27%	2568
	21st to end	Day	6% 7% 3 8% 9% 8% 9% 7% 9% 10% 23%	2600
July	1st to 10th	Day	6% 6% 3 9% 7% 8% 8% 7% 10% 12% 24%	5900
	11th to 20th	Day	6% 6% 3 9% 8% 8% 10% 7% 9% 11% 23%	5859
	21st to end	Day	6% 6% 3 10% 9% 8% 9% 8% 9% 12% 21%	5922
August	1st to 10th	Day	3 3 2 6% 5% 6% 7% 6% 9% 12% 39%	3905
	11th to 20th	Day	6% 4 2 7% 7% 7% 8% 7% 10% 12% 29%	3849
	21st to end	Day	7% 8% 4 12% 9% 7% 7% 5% 7% 6% 28%	4312
September	1st to 10th	Day	12% 7% 3 9% 7% 6% 7% 5% 7% 9% 28%	2400
	11th to 20th	Day	11% 6% 2 8% 7% 6% 7% 6% 7% 8% 32%	2373
	21st to end	Day	8% 5% 2 7% 6% 6% 5% 5% 6% 8% 42%	2200
October	1st to 10th	Day	8% 4 2 5% 4 5% 4 4 6% 8% 51%	1980
	11th to 20th	Day	6% 5% 2 6% 4 4 5% 3 5% 8% 52%	1900
	21st to end	Day	9% 5% 2 4 3 5% 3 3 5% 7% 52%	2090
November	1st to 10th	Day	8% 6% 3 5% 4 3 4 4 5% 8% 51%	1958
	11th to 20th	Day	10% 6% 3 6% 4 3 3 3 4 6% 52%	2000
	21st to end	Day	12% 6% 2 6% 5% 4 5% 4 5% 8% 43%	2000
December	1st to 10th	Day	17% 7% 2 6% 4 4 4 4 6% 7% 39%	3260
	11th to 20th	Day	9% 5% 2 5% 4 3 4 4 6% 8% 50%	3756
	21st to end	Day	14% 7% 3 7% 4 4 4 3 4 5% 45%	4862
January	1st to 10th	Night	16% 7% 2 6% 4 3 4 3 4 5% 46%	5888
	11th to 20th	Night	18% 8% 3 5% 3 3 2 2 5% 6% 45%	5900
	21st to end	Night	19% 7% 2 6% 4 3 4 3 6% 8% 37%	6016
February	1st to 10th	Night	14% 8% 3 7% 4 5% 4 4 5% 7% 41%	2400
	11th to 20th	Night	17% 8% 3 5% 3 3 3 3 6% 6% 43%	2338
	21st to end	Night	15% 8% 2 5% 4 4 4 3 6% 6% 43%	1980
March	1st to 10th	Night	17% 10% 3 6% 4 4 4 3 5% 6% 39%	5007
	11th to 20th	Night	10% 7% 2 6% 4 4 4 3 6% 7% 48%	4980
	21st to end	Night	13% 7% 2 6% 4 4 4 3 5% 7% 45%	5289
April	1st to 10th	Night	11% 5% 3 6% 4 4 4 3 6% 8% 46%	2000
	11th to 20th	Night	10% 6% 3 6% 5% 3 4 3 6% 5% 48%	1975
	21st to end	Night	5% 4 2 5% 3 4 5% 4 7% 9% 52%	2000
May	1st to 10th	Night	12% 8% 4 8% 6% 5% 5% 4 6% 8% 35%	4490
	11th to 20th	Night	12% 6% 2 6% 4 4 4 3 6% 8% 44%	4489
	21st to end	Night	5% 4 2 6% 4 4 4 4 6% 11% 49%	4922
June	1st to 10th	Night	6% 5% 2 5% 4 4 5% 4 7% 10% 47%	2000
	11th to 20th	Night	4 4 1 4 4 6% 6% 5% 10% 10% 47%	1824
	21st to end	Night	6% 6% 2 5% 5% 5% 5% 5% 8% 11% 43%	1800
July	1st to 10th	Night	3 4 2 5% 4 5% 6% 5% 9% 13% 44%	4078
	11th to 20th	Night	3 2 2 4 4 5% 6% 5% 8% 12% 49%	4111
	21st to end	Night	3 4 1 6% 5% 6% 7% 6% 10% 14% 38%	4929
August	1st to 10th	Night	1 2 1 3 3 4 4 4 7% 12% 58%	3244
	11th to 20th	Night	3 2 1 3 3 5% 5% 5% 9% 15% 49%	3200
	21st to end	Night	5% 4 2 7% 5% 6% 6% 6% 8% 10% 42%	3586
September	1st to 10th	Night	7% 5% 2 6% 5% 5% 7% 5% 7% 10% 41%	2000
	11th to 20th	Night	8% 5% 3 5% 4 4 5% 4 8% 10% 45%	2005
	21st to end	Night	6% 4 2 4 4 4 6% 4 6% 9% 53%	2200
October	1st to 10th	Night	6% 3 2 4 3 4 3 3 6% 7% 59%	2262
	11th to 20th	Night	5% 4 1 4 3 2 4 2 5% 7% 63%	2280
	21st to end	Night	9% 4 2 5% 3 3 4 3 4 6% 57%	2508
November	1st to 10th	Night	9% 5% 2 5% 4 3 4 3 4 7% 54%	2340
	11th to 20th	Night	10% 6% 2 4 4 3 4 3 5% 6% 53%	2400
	21st to end	Night	9% 7% 2 6% 4 4 4 4 5% 7% 49%	2400
December	1st to 10th	Night	11% 7% 3 8% 5% 4 5% 3 5% 6% 42%	3920
	11th to 20th	Night	9% 6% 2 5% 4 3 4 3 5% 6% 53%	4439
	21st to end	Night	14% 8% 3 7% 5% 3 4 3 4 5% 44%	6076

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	43% 6% 8% 18% 18% 7%	4078
	11th to 20th	Day	39% 5% 6% 16% 27% 6%	4080
	21st to end	Day	50% 6% 7% 13% 16% 8%	4908
February	1st to 10th	Day	44% 6% 9% 14% 18% 9%	2000
	11th to 20th	Day	39% 6% 11% 17% 18% 8%	1958
	21st to end	Day	45% 5% 11% 17% 17% 6%	1650
March	1st to 10th	Day	45% 7% 10% 17% 14% 8%	4887
	11th to 20th	Day	33% 8% 12% 16% 16% 15%	4980
	21st to end	Day	37% 7% 12% 19% 17% 7%	5642
April	1st to 10th	Day	36% 8% 12% 18% 16% 9%	2400
	11th to 20th	Day	38% 6% 12% 21% 14% 9%	2374
	21st to end	Day	31% 8% 12% 22% 21% 6%	2400
May	1st to 10th	Day	40% 10% 15% 23% 8% 3	5440
	11th to 20th	Day	29% 9% 14% 28% 17% 3	5408
	21st to end	Day	30% 11% 18% 31% 9% 1	5945
June	1st to 10th	Day	45% 11% 14% 20% 9% 1	2400
	11th to 20th	Day	41% 13% 17% 19% 9% 1	2568
	21st to end	Day	47% 14% 19% 15% 5%	2600
July	1st to 10th	Day	44% 14% 27% 15% 1	5836
	11th to 20th	Day	47% 16% 30% 5% 1	5790
	21st to end	Day	47% 17% 20% 15% 1	5752
August	1st to 10th	Day	30% 13% 17% 25% 16%	3893
	11th to 20th	Day	39% 13% 27% 16% 4	3885
	21st to end	Day	51% 11% 13% 14% 9% 1	4311
September	1st to 10th	Day	47% 13% 16% 12% 10% 2	2400
	11th to 20th	Day	43% 11% 14% 15% 13% 3	2373
	21st to end	Day	36% 8% 12% 20% 15% 9%	2200
October	1st to 10th	Day	28% 5% 7% 14% 20% 25%	3266
	11th to 20th	Day	19% 4 7% 22% 30% 19%	3140
	21st to end	Day	20% 5% 8% 13% 41% 13%	3428
November	1st to 10th	Day	30% 5% 11% 22% 24% 8%	1958
	11th to 20th	Day	33% 5% 7% 18% 24% 13%	2000
	21st to end	Day	38% 6% 9% 20% 19% 10%	2000
December	1st to 10th	Day	43% 6% 10% 16% 21% 5%	3260
	11th to 20th	Day	31% 8% 10% 22% 20% 10%	3754
	21st to end	Day	40% 6% 9% 15% 24% 5%	4862
January	1st to 10th	Night	41% 5% 7% 18% 22% 8%	5888
	11th to 20th	Night	41% 4 6% 16% 26% 8%	5900
	21st to end	Night	45% 4 11% 14% 16% 10%	6016
February	1st to 10th	Night	42% 5% 8% 16% 19% 10%	2400
	11th to 20th	Night	41% 5% 9% 17% 17% 11%	2339
	21st to end	Night	40% 7% 12% 15% 16% 10%	1980
March	1st to 10th	Night	44% 7% 10% 13% 15% 11%	5007
	11th to 20th	Night	33% 7% 12% 15% 19% 14%	4980
	21st to end	Night	37% 6% 11% 20% 18% 7%	5289
April	1st to 10th	Night	35% 8% 13% 17% 16% 11%	2000
	11th to 20th	Night	35% 6% 12% 20% 17% 10%	1975
	21st to end	Night	26% 6% 14% 24% 23% 6%	2000
May	1st to 10th	Night	41% 12% 15% 21% 9% 3	4520
	11th to 20th	Night	34% 8% 13% 26% 17% 1	4490
	21st to end	Night	27% 8% 19% 34% 11% 1	4931
June	1st to 10th	Night	31% 9% 18% 28% 14%	2000
	11th to 20th	Night	28% 11% 23% 27% 11%	1824
	21st to end	Night	33% 10% 27% 23% 7%	1800
July	1st to 10th	Night	28% 11% 39% 20% 1	4035
	11th to 20th	Night	25% 15% 47% 12% 2	4060
	21st to end	Night	30% 17% 28% 22% 2	4785
August	1st to 10th	Night	16% 10% 26% 31% 17%	3232
	11th to 20th	Night	21% 12% 40% 24% 2	3230
	21st to end	Night	35% 12% 20% 20% 12% 2	3586
September	1st to 10th	Night	35% 11% 23% 16% 12% 3	2000
	11th to 20th	Night	31% 12% 19% 19% 15% 4	2005
	21st to end	Night	27% 8% 17% 26% 15% 8%	2200
October	1st to 10th	Night	27% 5% 9% 15% 21% 23%	3756
	11th to 20th	Night	14% 4 7% 22% 29% 23%	3779
	21st to end	Night	19% 4 7% 11% 40% 18%	4120
November	1st to 10th	Night	30% 5% 9% 23% 23% 10%	2340
	11th to 20th	Night	32% 5% 8% 17% 26% 13%	2400
	21st to end	Night	34% 7% 8% 20% 21% 10%	2400
December	1st to 10th	Night	42% 5% 7% 20% 20% 6%	3920
	11th to 20th	Night	31% 6% 12% 22% 17% 12%	4440
	21st to end	Night	42% 6% 9% 12% 22% 8%	6076

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	20% 14% 40% 19% 6% 1	300
	11th to 20th	Day	14% 17% 36% 27% 6%	300
	21st to end	Day	22% 13% 43% 17% 5%	330
February	1st to 10th	Day	17% 17% 36% 24% 6%	300
	11th to 20th	Day	21% 18% 32% 20% 8% 1	300
	21st to end	Day	14% 19% 45% 18% 5%	249
March	1st to 10th	Day	16% 19% 38% 21% 6%	300
	11th to 20th	Day	18% 17% 38% 21% 5% 1	300
	21st to end	Day	17% 15% 34% 23% 11% 1	405
April	1st to 10th	Day	15% 12% 34% 27% 10% 2	500
	11th to 20th	Day	17% 12% 32% 23% 13% 2	492
	21st to end	Day	8% 7% 32% 31% 18% 3	500
May	1st to 10th	Day	11% 8% 28% 31% 17% 5%	503
	11th to 20th	Day	9% 5% 22% 34% 22% 7%	527
	21st to end	Day	4 3 14% 35% 28% 16%	573
June	1st to 10th	Day	10% 3 10% 29% 30% 18%	530
	11th to 20th	Day	9% 3 11% 32% 28% 17%	698
	21st to end	Day	8% 2 9% 29% 30% 22%	730
July	1st to 10th	Day	9% 3 6% 25% 29% 27%	721
	11th to 20th	Day	8% 2 3 17% 35% 34%	703
	21st to end	Day	8% 2 5% 18% 35% 33%	576
August	1st to 10th	Day	4 3 2 15% 35% 39%	526
	11th to 20th	Day	8% 2 3 11% 33% 43%	519
	21st to end	Day	10% 3 8% 19% 34% 26%	583
September	1st to 10th	Day	12% 2 5% 22% 35% 23%	530
	11th to 20th	Day	11% 3 7% 24% 38% 18%	530
	21st to end	Day	8% 4 10% 28% 35% 15%	530
October	1st to 10th	Day	7% 2 17% 42% 24% 9%	359
	11th to 20th	Day	7% 4 19% 39% 23% 7%	300
	21st to end	Day	17% 8% 20% 35% 16% 4	330
November	1st to 10th	Day	12% 6% 22% 35% 21% 4	300
	11th to 20th	Day	16% 10% 27% 32% 11% 3	300
	21st to end	Day	15% 12% 34% 25% 11% 3	300
December	1st to 10th	Day	16% 8% 37% 23% 9% 6%	300
	11th to 20th	Day	14% 13% 41% 24% 7% 1	300
	21st to end	Day	21% 14% 32% 22% 11% 1	330
January	1st to 10th	Night	17% 10% 30% 35% 8% 1	1000
	11th to 20th	Night	17% 9% 28% 38% 10%	1000
	21st to end	Night	19% 11% 32% 32% 7%	899
February	1st to 10th	Night	16% 9% 31% 35% 8% 1	800
	11th to 20th	Night	21% 11% 26% 32% 10% 1	783
	21st to end	Night	19% 11% 37% 28% 5%	660
March	1st to 10th	Night	15% 10% 32% 34% 9%	640
	11th to 20th	Night	13% 6% 29% 36% 16% 1	600
	21st to end	Night	10% 10% 26% 35% 18% 1	660
April	1st to 10th	Night	15% 9% 26% 35% 14% 1	600
	11th to 20th	Night	13% 7% 28% 34% 16% 1	593
	21st to end	Night	6% 6% 27% 38% 22% 1	600
May	1st to 10th	Night	9% 4 20% 40% 25% 2	600
	11th to 20th	Night	8% 3 15% 45% 27% 3	591
	21st to end	Night	6% 3 9% 36% 37% 10%	650
June	1st to 10th	Night	7% 2 5% 31% 46% 9%	600
	11th to 20th	Night	4 1 6% 21% 53% 16%	600
	21st to end	Night	9% 1 5% 20% 44% 21%	600
July	1st to 10th	Night	4 2 2 14% 46% 31%	585
	11th to 20th	Night	5% 2 1 5% 49% 38%	582
	21st to end	Night	4 2 2 12% 51% 30%	657
August	1st to 10th	Night	2 1 1 8% 44% 43%	597
	11th to 20th	Night	5% 1 2 9% 44% 40%	594
	21st to end	Night	8% 2 4 14% 46% 26%	660
September	1st to 10th	Night	9% 1 2 16% 47% 25%	600
	11th to 20th	Night	9% 1 6% 19% 50% 14%	605
	21st to end	Night	7% 2 7% 30% 44% 10%	800
October	1st to 10th	Night	7% 2 11% 39% 34% 7%	773
	11th to 20th	Night	7% 4 15% 36% 32% 7%	760
	21st to end	Night	11% 4 19% 37% 25% 4	836
November	1st to 10th	Night	12% 4 14% 42% 25% 4	780
	11th to 20th	Night	13% 5% 21% 40% 20% 2	800
	21st to end	Night	11% 5% 27% 38% 17% 1	800
December	1st to 10th	Night	15% 9% 24% 34% 17% 1	800
	11th to 20th	Night	15% 7% 26% 40% 12% 1	800
	21st to end	Night	19% 8% 31% 30% 11% 1	920

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