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 2024-11-05.

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% 6% 6% 6% 5% 7% 9% 36%	100905
	Night	10% 6% 2 6% 4 4 5% 4 6% 8% 45%	98129
Transparency	Day	39% 9% 14% 17% 15% 6%	104588
	Night	33% 8% 16% 19% 17% 7%	102585
Seeing	Day	12% 7% 19% 25% 23% 14%	14648
	Night	11% 5% 18% 31% 26% 9%	24276

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% 6% 2 7% 5% 5% 5% 5% 6% 9% 36%	2847
	11th to 20th	Day	11% 6% 2 5% 3 3 4 3 5% 6% 53%	2850
	21st to end	Day	21% 10% 4 7% 4 4 4 3 5% 6% 32%	3425
February	1st to 10th	Day	14% 8% 2 7% 5% 4 5% 4 5% 6% 38%	1900
	11th to 20th	Day	15% 7% 2 6% 4 4 4 4 6% 7% 43%	1848
	21st to end	Day	15% 9% 3 6% 5% 4 4 3 5% 8% 37%	1570
March	1st to 10th	Day	18% 9% 4 9% 5% 5% 5% 4 6% 8% 28%	3401
	11th to 20th	Day	12% 7% 3 8% 6% 5% 6% 5% 8% 9% 31%	3480
	21st to end	Day	11% 5% 2 6% 4 4 4 5% 6% 7% 46%	3936
April	1st to 10th	Day	9% 6% 2 6% 5% 5% 5% 5% 7% 8% 42%	2280
	11th to 20th	Day	13% 7% 3 6% 4 5% 5% 5% 6% 10% 39%	2254
	21st to end	Day	7% 5% 2 6% 4 5% 5% 5% 5% 8% 47%	2280
May	1st to 10th	Day	8% 5% 3 7% 5% 6% 6% 6% 9% 11% 35%	3765
	11th to 20th	Day	8% 6% 3 7% 5% 5% 5% 4 7% 9% 41%	3764
	21st to end	Day	5% 4 2 6% 5% 6% 6% 5% 7% 11% 44%	4129
June	1st to 10th	Day	9% 7% 3 9% 8% 7% 7% 6% 8% 9% 28%	2280
	11th to 20th	Day	6% 6% 2 7% 7% 8% 9% 8% 9% 12% 27%	2439
	21st to end	Day	7% 7% 3 9% 9% 8% 9% 7% 9% 9% 23%	2470
July	1st to 10th	Day	7% 8% 4 10% 8% 8% 8% 8% 10% 12% 18%	4120
	11th to 20th	Day	6% 7% 4 10% 9% 9% 9% 7% 8% 9% 20%	4093
	21st to end	Day	7% 7% 3 10% 10% 8% 9% 7% 9% 10% 18%	4118
August	1st to 10th	Day	4 3 2 6% 5% 6% 7% 6% 9% 12% 40%	3785
	11th to 20th	Day	6% 4 2 7% 7% 7% 8% 7% 10% 12% 29%	3729
	21st to end	Day	7% 8% 4 12% 9% 7% 7% 5% 7% 6% 28%	4180
September	1st to 10th	Day	13% 8% 3 9% 7% 6% 7% 5% 7% 9% 27%	2280
	11th to 20th	Day	11% 6% 2 8% 7% 6% 7% 6% 7% 8% 31%	2255
	21st to end	Day	8% 6% 2 7% 6% 6% 5% 5% 6% 8% 42%	2090
October	1st to 10th	Day	8% 4 2 5% 4 5% 4 4 6% 8% 51%	1948
	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	7% 5% 2 5% 4 3 4 4 5% 8% 51%	1898
	11th to 20th	Day	10% 6% 3 6% 4 3 3 4 5% 6% 52%	1900
	21st to end	Day	12% 6% 2 6% 5% 5% 5% 4 5% 8% 42%	1900
December	1st to 10th	Day	13% 7% 2 6% 3 4 4 3 7% 8% 43%	1900
	11th to 20th	Day	14% 8% 3 6% 5% 4 5% 4 6% 8% 37%	2396
	21st to end	Day	17% 8% 3 8% 4 5% 4 4 4 5% 38%	3405
January	1st to 10th	Night	15% 8% 3 7% 4 4 4 3 5% 6% 42%	4108
	11th to 20th	Night	14% 6% 2 4 3 3 3 3 5% 6% 50%	4120
	21st to end	Night	22% 8% 3 5% 4 3 4 3 5% 7% 38%	4212
February	1st to 10th	Night	14% 7% 2 7% 4 4 4 3 5% 7% 42%	2280
	11th to 20th	Night	16% 7% 2 5% 3 3 3 3 6% 7% 44%	2218
	21st to end	Night	15% 8% 2 5% 4 4 4 3 6% 6% 44%	1884
March	1st to 10th	Night	22% 11% 3 7% 4 4 4 3 5% 6% 31%	3479
	11th to 20th	Night	11% 8% 2 8% 4 5% 5% 4 7% 9% 36%	3480
	21st to end	Night	12% 6% 2 5% 3 4 4 4 6% 8% 46%	3695
April	1st to 10th	Night	11% 5% 2 6% 4 4 4 3 6% 8% 46%	1900
	11th to 20th	Night	11% 6% 3 7% 5% 4 4 3 6% 5% 47%	1875
	21st to end	Night	5% 4 2 5% 3 4 5% 4 7% 9% 52%	1900
May	1st to 10th	Night	10% 7% 3 7% 5% 5% 5% 4 6% 8% 40%	3130
	11th to 20th	Night	13% 6% 2 6% 4 4 5% 4 6% 8% 43%	3129
	21st to end	Night	4 3 1 4 3 4 5% 4 7% 12% 51%	3426
June	1st to 10th	Night	7% 5% 2 5% 5% 5% 5% 4 7% 11% 46%	1900
	11th to 20th	Night	4 4 1 4 5% 6% 6% 5% 10% 10% 47%	1733
	21st to end	Night	6% 6% 2 5% 5% 5% 5% 5% 7% 11% 43%	1710
July	1st to 10th	Night	4 5% 2 5% 5% 5% 6% 5% 10% 13% 40%	2850
	11th to 20th	Night	3 2 2 4 4 5% 6% 5% 8% 13% 47%	2871
	21st to end	Night	3 4 2 6% 5% 6% 7% 7% 11% 15% 34%	3435
August	1st to 10th	Night	1 2 1 3 3 4 4 4 7% 12% 58%	3144
	11th to 20th	Night	3 2 1 3 4 5% 5% 5% 9% 15% 48%	3100
	21st to end	Night	5% 4 3 7% 5% 6% 5% 6% 8% 10% 42%	3476
September	1st to 10th	Night	7% 5% 2 6% 5% 5% 7% 5% 7% 10% 41%	1900
	11th to 20th	Night	9% 5% 3 5% 4 4 5% 4 8% 10% 43%	1905
	21st to end	Night	6% 4 2 4 3 4 6% 4 5% 9% 53%	2090
October	1st to 10th	Night	6% 3 2 4 3 4 3 3 6% 7% 59%	2228
	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% 4 2 5% 4 3 4 3 4 7% 55%	2280
	11th to 20th	Night	10% 5% 2 4 4 3 4 3 5% 6% 54%	2280
	21st to end	Night	9% 7% 2 6% 4 4 4 4 5% 7% 48%	2280
December	1st to 10th	Night	13% 8% 3 6% 3 3 4 3 5% 7% 45%	2280
	11th to 20th	Night	11% 8% 2 6% 4 4 4 4 5% 7% 45%	2799
	21st to end	Night	15% 9% 3 8% 5% 3 4 3 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% 8% 15% 19% 9%	2848
	11th to 20th	Day	32% 5% 7% 20% 30% 6%	2850
	21st to end	Day	53% 5% 6% 13% 17% 6%	3425
February	1st to 10th	Day	45% 6% 9% 13% 18% 9%	1900
	11th to 20th	Day	39% 6% 10% 18% 18% 9%	1858
	21st to end	Day	44% 5% 11% 17% 17% 6%	1570
March	1st to 10th	Day	50% 9% 12% 15% 11% 3	3401
	11th to 20th	Day	44% 9% 14% 17% 12% 4	3480
	21st to end	Day	32% 8% 14% 17% 21% 8%	3936
April	1st to 10th	Day	36% 9% 13% 18% 16% 9%	2280
	11th to 20th	Day	39% 6% 12% 20% 14% 8%	2254
	21st to end	Day	32% 8% 11% 21% 22% 6%	2280
May	1st to 10th	Day	36% 12% 16% 22% 10% 4	3800
	11th to 20th	Day	35% 10% 12% 19% 20% 4	3768
	21st to end	Day	28% 11% 17% 33% 11% 1	4141
June	1st to 10th	Day	46% 11% 14% 20% 8% 1	2280
	11th to 20th	Day	41% 13% 16% 19% 10% 1	2439
	21st to end	Day	48% 14% 19% 14% 6%	2470
July	1st to 10th	Day	49% 14% 24% 13% 1	4056
	11th to 20th	Day	51% 17% 25% 6% 1	4024
	21st to end	Day	52% 16% 19% 11% 2	3987
August	1st to 10th	Day	29% 13% 16% 25% 16%	3773
	11th to 20th	Day	40% 13% 26% 16% 4 1	3765
	21st to end	Day	51% 11% 13% 14% 9% 1	4179
September	1st to 10th	Day	48% 12% 16% 11% 10% 2	2280
	11th to 20th	Day	44% 11% 14% 14% 12% 4	2255
	21st to end	Day	37% 8% 12% 20% 14% 9%	2090
October	1st to 10th	Day	28% 5% 7% 14% 20% 25%	3234
	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	29% 5% 11% 22% 24% 9%	1898
	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	42% 5% 8% 14% 22% 9%	4108
	11th to 20th	Night	34% 4 7% 18% 26% 11%	4120
	21st to end	Night	47% 4 7% 15% 19% 9%	4212
February	1st to 10th	Night	42% 5% 8% 16% 18% 10%	2280
	11th to 20th	Night	39% 5% 9% 17% 18% 12%	2219
	21st to end	Night	39% 7% 13% 14% 16% 10%	1884
March	1st to 10th	Night	51% 8% 12% 13% 12% 5%	3479
	11th to 20th	Night	41% 9% 15% 16% 14% 5%	3480
	21st to end	Night	34% 7% 12% 21% 19% 7%	3695
April	1st to 10th	Night	35% 8% 13% 17% 16% 11%	1900
	11th to 20th	Night	36% 6% 12% 20% 16% 9%	1875
	21st to end	Night	27% 6% 13% 24% 24% 7%	1900
May	1st to 10th	Night	34% 14% 16% 21% 12% 4	3160
	11th to 20th	Night	36% 9% 12% 20% 21% 2	3130
	21st to end	Night	22% 8% 21% 34% 14% 1	3435
June	1st to 10th	Night	31% 10% 18% 28% 13%	1900
	11th to 20th	Night	28% 10% 22% 27% 12%	1733
	21st to end	Night	34% 10% 26% 23% 7%	1710
July	1st to 10th	Night	30% 13% 39% 16% 1	2805
	11th to 20th	Night	24% 17% 45% 11% 3	2817
	21st to end	Night	32% 19% 30% 16% 2	3325
August	1st to 10th	Night	17% 10% 25% 31% 18%	3132
	11th to 20th	Night	22% 12% 39% 24% 2	3130
	21st to end	Night	35% 12% 19% 20% 12% 2	3476
September	1st to 10th	Night	36% 11% 22% 15% 12% 3	1900
	11th to 20th	Night	32% 12% 19% 18% 14% 5%	1905
	21st to end	Night	27% 8% 16% 26% 15% 8%	2090
October	1st to 10th	Night	27% 5% 9% 15% 21% 24%	3722
	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	29% 5% 9% 23% 24% 10%	2280
	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% 20% 6% 1	270
	11th to 20th	Day	13% 15% 36% 29% 6%	270
	21st to end	Day	22% 13% 43% 15% 5%	297
February	1st to 10th	Day	18% 17% 36% 23% 6%	270
	11th to 20th	Day	22% 15% 32% 21% 9% 1	270
	21st to end	Day	12% 20% 45% 19% 4	225
March	1st to 10th	Day	16% 17% 40% 22% 6%	270
	11th to 20th	Day	17% 16% 40% 22% 4 1	270
	21st to end	Day	16% 15% 33% 24% 11% 1	368
April	1st to 10th	Day	14% 12% 33% 28% 10% 2	460
	11th to 20th	Day	18% 12% 31% 23% 14% 2	452
	21st to end	Day	8% 8% 32% 30% 19% 3	460
May	1st to 10th	Day	10% 7% 28% 31% 19% 5%	463
	11th to 20th	Day	10% 4 20% 36% 23% 7%	487
	21st to end	Day	4 3 13% 34% 29% 16%	529
June	1st to 10th	Day	11% 3 9% 28% 31% 19%	490
	11th to 20th	Day	9% 3 11% 31% 28% 17%	649
	21st to end	Day	8% 3 9% 28% 30% 21%	680
July	1st to 10th	Day	10% 3 6% 23% 30% 28%	671
	11th to 20th	Day	8% 2 3 17% 35% 35%	654
	21st to end	Day	8% 2 5% 16% 35% 34%	532
August	1st to 10th	Day	5% 3 2 15% 34% 40%	486
	11th to 20th	Day	9% 2 3 12% 32% 43%	479
	21st to end	Day	10% 3 8% 19% 34% 27%	539
September	1st to 10th	Day	13% 2 4 20% 35% 25%	490
	11th to 20th	Day	12% 3 8% 23% 36% 18%	490
	21st to end	Day	9% 4 9% 26% 36% 16%	490
October	1st to 10th	Day	7% 2 17% 41% 24% 9%	348
	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% 5% 20% 37% 21% 4	282
	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% 8% 28% 39% 10%	950
	21st to end	Night	20% 11% 31% 32% 7%	855
February	1st to 10th	Night	16% 9% 32% 35% 7% 1	760
	11th to 20th	Night	20% 11% 25% 33% 10% 1	743
	21st to end	Night	18% 11% 37% 28% 5%	628
March	1st to 10th	Night	15% 9% 32% 34% 10%	608
	11th to 20th	Night	13% 5% 28% 36% 16% 1	570
	21st to end	Night	11% 10% 25% 35% 18% 1	627
April	1st to 10th	Night	14% 8% 27% 36% 15% 1	570
	11th to 20th	Night	13% 7% 28% 34% 16% 1	563
	21st to end	Night	6% 6% 27% 38% 22% 1	570
May	1st to 10th	Night	8% 4 20% 40% 26% 2	570
	11th to 20th	Night	7% 3 13% 45% 29% 3	561
	21st to end	Night	6% 3 9% 35% 37% 10%	617
June	1st to 10th	Night	7% 2 5% 31% 46% 10%	570
	11th to 20th	Night	4 1 6% 21% 52% 16%	570
	21st to end	Night	9% 1 5% 21% 43% 21%	570
July	1st to 10th	Night	5% 3 2 13% 46% 32%	555
	11th to 20th	Night	5% 1 1 5% 50% 37%	552
	21st to end	Night	4 2 2 12% 50% 30%	624
August	1st to 10th	Night	2 1 1 8% 44% 43%	567
	11th to 20th	Night	5% 1 2 9% 43% 40%	564
	21st to end	Night	8% 2 4 14% 45% 26%	627
September	1st to 10th	Night	9% 1 2 15% 47% 26%	570
	11th to 20th	Night	10% 1 6% 19% 49% 15%	575
	21st to end	Night	8% 2 7% 29% 45% 10%	760
October	1st to 10th	Night	7% 2 11% 39% 34% 7%	760
	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	11% 4 14% 43% 25% 4	760
	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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