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 2024-01-12.

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	11% 6% 3 6% 6% 4 6% 6% 6% 8% 37%	75314
	Night	9% 5% 2 5% 5% 3 4 5% 6% 8% 47%	74392
Transparency	Day	41% 9% 13% 17% 15% 5%	75051
	Night	33% 8% 15% 20% 17% 8%	74175
Seeing	Day	12% 7% 19% 25% 23% 15%	13527
	Night	11% 5% 18% 31% 26% 9%	23274

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	14% 6% 3 6% 5% 3 5% 5% 5% 7% 40%	1707
	11th to 20th	Day	13% 7% 3 5% 4 3 4 4 5% 7% 45%	1629
	21st to end	Day	17% 7% 4 4 5% 3 4 4 5% 6% 41%	1955
February	1st to 10th	Day	14% 8% 3 6% 6% 3 5% 5% 5% 6% 39%	1800
	11th to 20th	Day	14% 6% 3 5% 5% 3 4 4 6% 8% 43%	1748
	21st to end	Day	16% 9% 3 5% 6% 3 4 4 5% 8% 37%	1480
March	1st to 10th	Day	12% 7% 3 6% 5% 3 4 5% 5% 8% 42%	1957
	11th to 20th	Day	12% 7% 3 6% 6% 3 5% 6% 8% 8% 37%	1980
	21st to end	Day	10% 4 2 5% 4 3 4 6% 7% 8% 47%	2245
April	1st to 10th	Day	9% 5% 2 5% 5% 3 6% 6% 6% 9% 43%	2160
	11th to 20th	Day	13% 7% 3 5% 5% 3 5% 5% 6% 10% 39%	2134
	21st to end	Day	7% 4 3 6% 5% 4 6% 6% 5% 8% 46%	2160
May	1st to 10th	Day	7% 4 2 5% 5% 4 5% 6% 6% 10% 46%	2160
	11th to 20th	Day	8% 5% 2 5% 6% 4 6% 5% 7% 9% 43%	2124
	21st to end	Day	7% 4 4 7% 6% 5% 7% 7% 7% 10% 37%	2337
June	1st to 10th	Day	9% 7% 3 7% 8% 5% 8% 7% 8% 10% 27%	2160
	11th to 20th	Day	6% 5% 3 6% 7% 5% 10% 9% 9% 12% 28%	2310
	21st to end	Day	7% 7% 4 8% 10% 6% 10% 9% 9% 10% 22%	2340
July	1st to 10th	Day	10% 8% 5% 9% 9% 6% 8% 9% 8% 9% 20%	2340
	11th to 20th	Day	10% 7% 4 9% 10% 6% 10% 9% 8% 8% 19%	2327
	21st to end	Day	9% 7% 4 9% 9% 5% 9% 8% 7% 10% 24%	2350
August	1st to 10th	Day	6% 5% 4 8% 8% 6% 9% 9% 10% 13% 22%	2148
	11th to 20th	Day	11% 6% 3 8% 9% 6% 9% 9% 9% 11% 20%	2125
	21st to end	Day	9% 8% 4 8% 9% 5% 8% 8% 7% 8% 27%	2376
September	1st to 10th	Day	10% 7% 3 8% 8% 5% 7% 8% 7% 10% 28%	2160
	11th to 20th	Day	11% 6% 3 6% 8% 5% 7% 7% 7% 8% 31%	2137
	21st to end	Day	9% 6% 3 5% 7% 4 6% 6% 6% 8% 40%	1980
October	1st to 10th	Day	7% 4 2 4 5% 3 5% 5% 6% 8% 51%	1846
	11th to 20th	Day	6% 5% 2 5% 5% 3 5% 5% 5% 8% 50%	1800
	21st to end	Day	10% 5% 2 4 4 3 3 4 5% 7% 51%	1980
November	1st to 10th	Day	7% 5% 3 4 4 3 4 4 5% 8% 52%	1858
	11th to 20th	Day	10% 5% 3 5% 4 2 3 4 5% 6% 52%	1900
	21st to end	Day	12% 5% 2 5% 6% 3 5% 5% 5% 7% 43%	1900
December	1st to 10th	Day	13% 7% 3 5% 4 3 4 4 6% 8% 43%	1900
	11th to 20th	Day	14% 7% 3 6% 5% 3 5% 5% 6% 8% 38%	2396
	21st to end	Day	17% 8% 3 7% 5% 3 4 5% 4 5% 38%	3405
January	1st to 10th	Night	16% 5% 2 5% 4 3 4 4 5% 7% 44%	2458
	11th to 20th	Night	13% 6% 3 4 4 3 3 3 5% 7% 49%	2360
	21st to end	Night	16% 6% 3 5% 5% 2 4 4 5% 6% 43%	2394
February	1st to 10th	Night	15% 7% 3 6% 5% 3 4 4 4 7% 42%	2160
	11th to 20th	Night	16% 7% 2 4 4 2 4 4 5% 7% 45%	2098
	21st to end	Night	15% 7% 3 5% 4 3 5% 4 5% 7% 42%	1776
March	1st to 10th	Night	11% 6% 2 5% 5% 3 4 4 6% 9% 46%	2016
	11th to 20th	Night	11% 6% 3 5% 5% 3 5% 5% 6% 9% 42%	1980
	21st to end	Night	9% 4 2 4 4 3 4 5% 4 8% 54%	2111
April	1st to 10th	Night	11% 4 3 5% 5% 3 4 5% 6% 8% 47%	1800
	11th to 20th	Night	11% 6% 3 6% 6% 3 4 5% 6% 6% 47%	1775
	21st to end	Night	5% 4 3 5% 3 3 5% 5% 7% 9% 53%	1800
May	1st to 10th	Night	7% 3 2 4 3 2 4 4 6% 10% 54%	1800
	11th to 20th	Night	6% 4 2 4 4 2 5% 6% 7% 10% 50%	1769
	21st to end	Night	5% 3 2 3 4 3 5% 5% 7% 10% 53%	1938
June	1st to 10th	Night	7% 4 3 5% 5% 3 5% 5% 7% 10% 46%	1800
	11th to 20th	Night	3 3 2 4 5% 4 7% 6% 9% 10% 48%	1642
	21st to end	Night	7% 6% 2 4 6% 3 7% 5% 7% 11% 43%	1620
July	1st to 10th	Night	5% 5% 3 5% 5% 3 5% 6% 9% 12% 41%	1620
	11th to 20th	Night	4 3 2 5% 5% 4 6% 7% 9% 13% 42%	1628
	21st to end	Night	4 4 3 6% 4 3 6% 8% 8% 12% 42%	1968
August	1st to 10th	Night	2 3 1 4 4 4 4 5% 8% 14% 53%	1790
	11th to 20th	Night	5% 3 2 5% 6% 5% 6% 8% 10% 14% 38%	1776
	21st to end	Night	6% 4 3 5% 5% 3 5% 7% 8% 11% 43%	1980
September	1st to 10th	Night	5% 4 3 5% 6% 3 7% 6% 7% 10% 43%	1800
	11th to 20th	Night	8% 5% 3 5% 5% 4 4 6% 8% 11% 44%	1804
	21st to end	Night	7% 4 2 4 4 3 6% 5% 5% 9% 52%	1980
October	1st to 10th	Night	6% 3 1 3 4 3 4 4 5% 8% 60%	2110
	11th to 20th	Night	6% 3 1 4 4 1 3 3 5% 7% 61%	2160
	21st to end	Night	10% 4 2 4 4 2 3 4 4 6% 57%	2376
November	1st to 10th	Night	9% 4 2 4 4 2 4 4 4 7% 56%	2220
	11th to 20th	Night	10% 5% 2 4 4 2 4 4 5% 6% 54%	2280
	21st to end	Night	9% 7% 3 5% 5% 3 4 5% 5% 7% 48%	2280
December	1st to 10th	Night	13% 7% 3 5% 4 2 3 4 5% 7% 46%	2280
	11th to 20th	Night	11% 8% 2 6% 5% 3 5% 5% 5% 7% 45%	2799
	21st to end	Night	15% 9% 4 7% 6% 2 4 4 5% 5% 39%	4244

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	42% 6% 9% 17% 19% 8%	1708
	11th to 20th	Day	39% 5% 8% 18% 23% 7%	1629
	21st to end	Day	45% 5% 6% 17% 18% 9%	1955
February	1st to 10th	Day	45% 6% 9% 14% 18% 9%	1800
	11th to 20th	Day	39% 6% 10% 18% 18% 9%	1758
	21st to end	Day	45% 6% 11% 17% 16% 5%	1480
March	1st to 10th	Day	39% 6% 11% 21% 18% 5%	1957
	11th to 20th	Day	42% 7% 13% 14% 18% 6%	1980
	21st to end	Day	32% 7% 15% 23% 17% 6%	2245
April	1st to 10th	Day	35% 9% 13% 18% 16% 8%	2160
	11th to 20th	Day	39% 6% 12% 21% 14% 8%	2134
	21st to end	Day	32% 8% 11% 21% 21% 6%	2160
May	1st to 10th	Day	31% 8% 12% 26% 17% 6%	2160
	11th to 20th	Day	35% 9% 14% 22% 18% 2	2128
	21st to end	Day	37% 10% 15% 23% 14% 1	2337
June	1st to 10th	Day	47% 11% 13% 20% 8% 1	2160
	11th to 20th	Day	41% 13% 16% 20% 10% 1	2310
	21st to end	Day	49% 14% 18% 13% 6%	2340
July	1st to 10th	Day	53% 14% 17% 15% 1	2276
	11th to 20th	Day	54% 15% 19% 10% 2	2258
	21st to end	Day	47% 14% 20% 16% 3	2219
August	1st to 10th	Day	45% 16% 22% 15% 3	2136
	11th to 20th	Day	52% 15% 18% 12% 2 1	2125
	21st to end	Day	50% 13% 17% 13% 6% 1	2376
September	1st to 10th	Day	46% 13% 16% 12% 10% 2	2160
	11th to 20th	Day	45% 11% 15% 14% 12% 4	2137
	21st to end	Day	39% 8% 12% 19% 15% 8%	1980
October	1st to 10th	Day	29% 7% 11% 22% 20% 11%	1846
	11th to 20th	Day	31% 5% 11% 18% 22% 13%	1800
	21st to end	Day	31% 5% 8% 17% 26% 13%	1980
November	1st to 10th	Day	29% 5% 11% 22% 25% 9%	1858
	11th to 20th	Day	32% 5% 7% 19% 24% 12%	1900
	21st to end	Day	39% 5% 9% 19% 18% 10%	1900
December	1st to 10th	Day	37% 8% 11% 22% 16% 7%	1900
	11th to 20th	Day	42% 6% 9% 15% 19% 9%	2394
	21st to end	Day	46% 6% 11% 12% 21% 4	3405
January	1st to 10th	Night	40% 5% 9% 16% 21% 10%	2458
	11th to 20th	Night	36% 4 9% 17% 21% 13%	2360
	21st to end	Night	42% 4 8% 15% 20% 11%	2394
February	1st to 10th	Night	43% 5% 8% 16% 18% 10%	2160
	11th to 20th	Night	38% 5% 9% 18% 18% 12%	2099
	21st to end	Night	40% 7% 13% 14% 15% 11%	1776
March	1st to 10th	Night	35% 6% 12% 19% 20% 8%	2016
	11th to 20th	Night	37% 7% 17% 16% 16% 8%	1980
	21st to end	Night	29% 6% 14% 22% 23% 7%	2111
April	1st to 10th	Night	34% 7% 14% 18% 16% 10%	1800
	11th to 20th	Night	37% 6% 12% 20% 16% 9%	1775
	21st to end	Night	26% 6% 13% 24% 24% 7%	1800
May	1st to 10th	Night	25% 7% 14% 29% 18% 7%	1800
	11th to 20th	Night	28% 10% 15% 23% 21% 2	1770
	21st to end	Night	24% 9% 17% 30% 18% 1	1939
June	1st to 10th	Night	32% 10% 18% 28% 13%	1800
	11th to 20th	Night	27% 11% 23% 27% 12%	1642
	21st to end	Night	34% 10% 25% 23% 7%	1620
July	1st to 10th	Night	33% 12% 32% 21% 2	1575
	11th to 20th	Night	28% 18% 31% 18% 5%	1574
	21st to end	Night	29% 14% 32% 21% 4	1858
August	1st to 10th	Night	20% 13% 36% 27% 4	1778
	11th to 20th	Night	31% 16% 31% 18% 3	1776
	21st to end	Night	33% 13% 24% 22% 7% 2	1980
September	1st to 10th	Night	33% 12% 23% 16% 12% 3	1800
	11th to 20th	Night	32% 12% 19% 18% 13% 5%	1804
	21st to end	Night	28% 8% 16% 25% 15% 7%	1980
October	1st to 10th	Night	24% 6% 14% 24% 19% 14%	2110
	11th to 20th	Night	22% 6% 11% 22% 24% 15%	2160
	21st to end	Night	29% 4 8% 16% 27% 16%	2376
November	1st to 10th	Night	29% 5% 9% 23% 24% 10%	2220
	11th to 20th	Night	31% 4 8% 18% 26% 12%	2280
	21st to end	Night	35% 7% 8% 20% 21% 10%	2280
December	1st to 10th	Night	39% 6% 9% 21% 19% 7%	2280
	11th to 20th	Night	38% 6% 10% 15% 16% 15%	2800
	21st to end	Night	46% 6% 10% 13% 18% 7%	4244

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% 13% 39% 21% 6% 1	270
	11th to 20th	Day	13% 14% 35% 31% 7%	243
	21st to end	Day	22% 12% 44% 16% 6%	264
February	1st to 10th	Day	18% 16% 35% 24% 6%	240
	11th to 20th	Day	20% 15% 32% 22% 10% 1	240
	21st to end	Day	13% 19% 43% 21% 4	198
March	1st to 10th	Day	13% 17% 41% 23% 6%	240
	11th to 20th	Day	18% 15% 40% 22% 5% 1	240
	21st to end	Day	16% 13% 33% 26% 11% 1	331
April	1st to 10th	Day	14% 11% 32% 30% 11% 2	420
	11th to 20th	Day	19% 11% 29% 23% 15% 2	412
	21st to end	Day	8% 7% 31% 31% 19% 4	420
May	1st to 10th	Day	9% 6% 26% 32% 21% 5%	423
	11th to 20th	Day	9% 3 19% 36% 25% 8%	447
	21st to end	Day	5% 2 11% 34% 31% 18%	485
June	1st to 10th	Day	11% 2 8% 26% 32% 20%	450
	11th to 20th	Day	8% 3 10% 32% 29% 18%	600
	21st to end	Day	8% 3 9% 28% 31% 22%	630
July	1st to 10th	Day	10% 3 6% 22% 30% 29%	621
	11th to 20th	Day	8% 2 3 17% 35% 34%	605
	21st to end	Day	9% 2 5% 15% 34% 35%	488
August	1st to 10th	Day	5% 3 2 13% 34% 42%	446
	11th to 20th	Day	9% 2 3 11% 32% 43%	439
	21st to end	Day	11% 2 7% 18% 33% 28%	495
September	1st to 10th	Day	10% 2 4 20% 37% 27%	450
	11th to 20th	Day	11% 3 6% 24% 37% 19%	450
	21st to end	Day	9% 3 8% 27% 36% 17%	450
October	1st to 10th	Day	6% 2 17% 40% 26% 10%	316
	11th to 20th	Day	8% 4 17% 39% 24% 8%	270
	21st to end	Day	19% 8% 19% 34% 15% 5%	297
November	1st to 10th	Day	12% 5% 20% 36% 22% 4	270
	11th to 20th	Day	17% 11% 26% 32% 11% 3	270
	21st to end	Day	17% 11% 33% 25% 11% 3	270
December	1st to 10th	Day	15% 8% 35% 25% 10% 7%	270
	11th to 20th	Day	16% 13% 41% 24% 6%	270
	21st to end	Day	22% 15% 29% 22% 11% 1	297
January	1st to 10th	Night	17% 9% 29% 35% 8% 1	950
	11th to 20th	Night	15% 7% 28% 39% 11%	908
	21st to end	Night	19% 10% 30% 33% 7%	810
February	1st to 10th	Night	17% 9% 31% 35% 8% 1	720
	11th to 20th	Night	19% 11% 26% 33% 11% 1	703
	21st to end	Night	19% 10% 37% 29% 5%	592
March	1st to 10th	Night	14% 8% 32% 35% 10%	576
	11th to 20th	Night	14% 5% 28% 36% 17% 1	540
	21st to end	Night	10% 10% 25% 36% 19% 1	594
April	1st to 10th	Night	14% 7% 26% 36% 15% 1	540
	11th to 20th	Night	14% 7% 27% 34% 17% 2	533
	21st to end	Night	6% 6% 27% 38% 22% 1	540
May	1st to 10th	Night	7% 3 20% 41% 27% 2	540
	11th to 20th	Night	7% 2 13% 46% 30% 3	531
	21st to end	Night	6% 3 8% 33% 39% 11%	584
June	1st to 10th	Night	7% 1 5% 29% 47% 10%	540
	11th to 20th	Night	3 1 6% 21% 53% 16%	540
	21st to end	Night	10% 1 4 20% 44% 21%	540
July	1st to 10th	Night	5% 2 2 12% 46% 32%	525
	11th to 20th	Night	5% 1 1 6% 50% 37%	522
	21st to end	Night	4 2 2 12% 49% 31%	591
August	1st to 10th	Night	2 1 1 8% 43% 45%	537
	11th to 20th	Night	5% 1 2 8% 43% 40%	534
	21st to end	Night	9% 2 4 13% 45% 27%	594
September	1st to 10th	Night	7% 1 2 15% 48% 28%	540
	11th to 20th	Night	10% 1 6% 19% 49% 15%	544
	21st to end	Night	8% 1 6% 29% 46% 10%	720
October	1st to 10th	Night	7% 2 10% 38% 36% 7%	720
	11th to 20th	Night	7% 4 14% 36% 33% 7%	720
	21st to end	Night	12% 5% 19% 35% 25% 4	792
November	1st to 10th	Night	11% 4 13% 43% 26% 4	740
	11th to 20th	Night	12% 5% 20% 40% 21% 2	760
	21st to end	Night	11% 5% 27% 38% 17% 1	760
December	1st to 10th	Night	16% 8% 23% 34% 18% 1	760
	11th to 20th	Night	15% 7% 26% 40% 12% 1	760
	21st to end	Night	20% 8% 30% 30% 12% 1	874

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