New Orleans
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the New Orleans clear sky chart from 2005-11-06 to 2025-09-04.

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% 2 7% 5% 5% 6% 5% 7% 9% 39%	125394
	Night	11% 6% 2 5% 4 4 4 4 6% 8% 46%	123117
Transparency	Day	37% 9% 14% 18% 15% 6%	129094
	Night	33% 8% 15% 19% 17% 7%	127491
Seeing	Day	12% 7% 20% 25% 23% 13%	15682
	Night	12% 6% 18% 29% 26% 8%	25040

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	16% 6% 3 5% 5% 4 4 4 5% 7% 41%	4320
	11th to 20th	Day	13% 8% 2 7% 4 3 4 2 4 5% 48%	4405
	21st to end	Day	21% 8% 3 6% 5% 4 4 4 5% 5% 35%	4972
February	1st to 10th	Day	16% 8% 2 7% 5% 4 4 3 5% 6% 39%	2000
	11th to 20th	Day	15% 7% 2 6% 4 3 4 4 5% 8% 41%	1948
	21st to end	Day	16% 8% 3 7% 5% 5% 5% 3 4 7% 38%	1650
March	1st to 10th	Day	18% 9% 3 7% 4 4 4 3 5% 7% 36%	4701
	11th to 20th	Day	11% 5% 2 5% 4 4 4 4 7% 9% 46%	4980
	21st to end	Day	13% 7% 3 7% 4 5% 4 3 5% 7% 42%	5737
April	1st to 10th	Day	11% 6% 2 6% 5% 4 5% 5% 6% 9% 42%	2400
	11th to 20th	Day	13% 6% 3 7% 4 4 4 4 7% 8% 41%	2374
	21st to end	Day	8% 5% 2 5% 5% 4 5% 5% 7% 9% 45%	2400
May	1st to 10th	Day	14% 5% 2 7% 5% 5% 5% 4 7% 10% 35%	5405
	11th to 20th	Day	8% 3 2 5% 5% 5% 5% 5% 6% 9% 47%	5404
	21st to end	Day	6% 4 2 6% 6% 5% 7% 6% 9% 10% 39%	5932
June	1st to 10th	Day	9% 6% 3 9% 6% 6% 7% 6% 9% 10% 30%	2400
	11th to 20th	Day	5% 5% 2 7% 7% 8% 8% 8% 10% 11% 29%	2467
	21st to end	Day	6% 6% 3 9% 7% 8% 8% 8% 10% 11% 25%	2600
July	1st to 10th	Day	6% 5% 2 8% 7% 7% 9% 7% 10% 12% 27%	5900
	11th to 20th	Day	5% 5% 3 9% 8% 8% 9% 7% 10% 12% 23%	5634
	21st to end	Day	6% 5% 3 9% 7% 8% 8% 6% 10% 13% 25%	5922
August	1st to 10th	Day	4 3 1 4 4 5% 6% 5% 8% 12% 47%	3905
	11th to 20th	Day	5% 4 2 6% 5% 6% 8% 7% 9% 12% 35%	3849
	21st to end	Day	8% 6% 4 10% 8% 7% 6% 5% 7% 8% 32%	4312
September	1st to 10th	Day	10% 6% 2 8% 7% 7% 7% 5% 8% 9% 31%	2316
	11th to 20th	Day	10% 6% 2 8% 7% 6% 6% 5% 6% 9% 36%	2216
	21st to end	Day	8% 4 2 5% 5% 6% 4 4 7% 7% 48%	2090
October	1st to 10th	Day	7% 4 1 4 4 4 5% 4 6% 7% 53%	2025
	11th to 20th	Day	7% 4 2 5% 4 4 3 4 6% 7% 55%	1900
	21st to end	Day	10% 4 2 5% 4 3 3 3 5% 8% 53%	2090
November	1st to 10th	Day	9% 4 2 5% 3 4 4 3 5% 8% 52%	1958
	11th to 20th	Day	12% 5% 2 5% 4 3 3 3 5% 6% 53%	1942
	21st to end	Day	12% 5% 2 6% 4 4 6% 5% 6% 7% 43%	1800
December	1st to 10th	Day	17% 6% 3 6% 4 4 5% 3 5% 6% 41%	2930
	11th to 20th	Day	9% 7% 2 6% 4 4 4 3 5% 7% 49%	3538
	21st to end	Day	16% 8% 3 6% 4 4 4 3 4 6% 43%	4972
January	1st to 10th	Night	16% 8% 4 6% 4 3 3 3 4 5% 45%	5497
	11th to 20th	Night	19% 8% 2 4 2 3 2 2 4 6% 47%	5454
	21st to end	Night	20% 7% 2 5% 4 4 4 3 5% 7% 39%	5984
February	1st to 10th	Night	15% 7% 3 7% 4 4 4 3 5% 6% 42%	2400
	11th to 20th	Night	18% 7% 3 6% 4 3 3 3 4 6% 42%	2338
	21st to end	Night	18% 8% 2 6% 4 3 4 4 5% 5% 41%	1980
March	1st to 10th	Night	19% 10% 2 6% 4 3 4 3 4 6% 38%	5193
	11th to 20th	Night	11% 6% 2 5% 4 4 4 4 5% 6% 50%	4980
	21st to end	Night	15% 6% 2 5% 3 4 4 4 5% 6% 47%	5192
April	1st to 10th	Night	14% 7% 2 6% 4 3 4 4 6% 6% 45%	2000
	11th to 20th	Night	12% 7% 3 5% 4 4 4 3 5% 6% 47%	1975
	21st to end	Night	6% 4 1 4 3 4 4 4 6% 8% 55%	2000
May	1st to 10th	Night	14% 7% 3 8% 5% 4 5% 4 5% 9% 36%	4490
	11th to 20th	Night	13% 5% 2 6% 4 4 4 4 6% 8% 45%	4489
	21st to end	Night	5% 4 1 6% 4 5% 4 4 7% 11% 48%	4922
June	1st to 10th	Night	7% 5% 2 5% 4 4 5% 4 7% 12% 45%	2000
	11th to 20th	Night	3 3 1 5% 5% 4 6% 6% 8% 12% 47%	1923
	21st to end	Night	6% 4 2 6% 4 5% 5% 4 9% 12% 44%	1800
July	1st to 10th	Night	3 3 2 6% 4 5% 7% 5% 9% 14% 41%	4078
	11th to 20th	Night	3 3 1 4 3 4 5% 5% 9% 13% 50%	4312
	21st to end	Night	2 4 2 6% 5% 6% 6% 6% 10% 13% 40%	4929
August	1st to 10th	Night	1 2 1 4 3 3 5% 5% 7% 12% 56%	3244
	11th to 20th	Night	3 2 1 4 4 4 6% 5% 10% 14% 48%	3200
	21st to end	Night	5% 4 2 7% 6% 5% 6% 6% 8% 10% 41%	3586
September	1st to 10th	Night	7% 5% 3 7% 4 5% 6% 4 9% 11% 40%	1930
	11th to 20th	Night	8% 5% 2 6% 5% 5% 5% 4 8% 10% 43%	1943
	21st to end	Night	9% 4 1 5% 3 3 4 4 6% 8% 52%	2090
October	1st to 10th	Night	7% 3 1 4 3 3 3 2 5% 8% 59%	2149
	11th to 20th	Night	6% 4 2 4 3 3 3 2 4 8% 60%	2280
	21st to end	Night	10% 4 2 5% 3 4 4 3 4 5% 56%	2508
November	1st to 10th	Night	10% 5% 2 5% 4 3 3 2 4 6% 56%	2340
	11th to 20th	Night	11% 5% 2 4 4 4 4 3 4 6% 54%	2451
	21st to end	Night	10% 5% 2 6% 4 5% 4 3 5% 6% 49%	2600
December	1st to 10th	Night	11% 7% 3 7% 5% 5% 4 3 5% 7% 43%	4250
	11th to 20th	Night	11% 6% 2 6% 5% 4 4 3 5% 6% 50%	4626
	21st to end	Night	17% 9% 3 6% 4 3 3 3 3 4 44%	5984

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	40% 6% 8% 17% 21% 7%	4321
	11th to 20th	Day	38% 5% 7% 15% 29% 6%	4405
	21st to end	Day	50% 5% 8% 13% 16% 8%	4972
February	1st to 10th	Day	45% 6% 9% 13% 17% 10%	2000
	11th to 20th	Day	40% 7% 9% 17% 19% 8%	1958
	21st to end	Day	45% 7% 11% 14% 18% 6%	1650
March	1st to 10th	Day	45% 7% 10% 16% 13% 9%	4701
	11th to 20th	Day	32% 8% 11% 17% 16% 15%	4980
	21st to end	Day	39% 8% 11% 19% 16% 7%	5739
April	1st to 10th	Day	36% 10% 13% 17% 17% 9%	2400
	11th to 20th	Day	38% 7% 10% 20% 18% 8%	2374
	21st to end	Day	30% 9% 13% 22% 21% 6%	2400
May	1st to 10th	Day	40% 11% 16% 21% 9% 3	5440
	11th to 20th	Day	31% 8% 14% 27% 18% 2	5408
	21st to end	Day	32% 11% 18% 29% 10% 1	5945
June	1st to 10th	Day	41% 10% 17% 21% 10% 1	2400
	11th to 20th	Day	39% 13% 19% 19% 9% 1	2467
	21st to end	Day	44% 15% 19% 15% 7%	2600
July	1st to 10th	Day	41% 14% 27% 16% 2	5836
	11th to 20th	Day	44% 17% 31% 7% 1	5566
	21st to end	Day	43% 15% 20% 20% 2	5752
August	1st to 10th	Day	26% 10% 16% 27% 21%	3893
	11th to 20th	Day	35% 12% 24% 23% 6% 1	3885
	21st to end	Day	47% 11% 14% 15% 12% 1	4311
September	1st to 10th	Day	44% 14% 16% 13% 10% 4	2316
	11th to 20th	Day	40% 12% 15% 16% 13% 5%	2216
	21st to end	Day	32% 10% 12% 22% 15% 9%	2090
October	1st to 10th	Day	27% 5% 8% 13% 21% 25%	3363
	11th to 20th	Day	17% 4 7% 23% 27% 23%	3140
	21st to end	Day	20% 5% 8% 13% 39% 16%	3428
November	1st to 10th	Day	28% 7% 9% 23% 24% 8%	1958
	11th to 20th	Day	32% 5% 7% 20% 25% 12%	1942
	21st to end	Day	36% 7% 9% 19% 18% 10%	1800
December	1st to 10th	Day	43% 6% 9% 15% 22% 4	2930
	11th to 20th	Day	33% 7% 9% 21% 22% 8%	3536
	21st to end	Day	41% 7% 8% 15% 25% 4	4972
January	1st to 10th	Night	41% 5% 7% 15% 23% 8%	5497
	11th to 20th	Night	40% 4 6% 16% 28% 7%	5454
	21st to end	Night	44% 4 10% 14% 17% 10%	5984
February	1st to 10th	Night	42% 5% 9% 17% 19% 9%	2400
	11th to 20th	Night	42% 5% 8% 16% 19% 11%	2339
	21st to end	Night	41% 8% 11% 15% 14% 11%	1980
March	1st to 10th	Night	45% 7% 10% 12% 17% 10%	5193
	11th to 20th	Night	32% 9% 12% 14% 19% 15%	4980
	21st to end	Night	35% 6% 12% 20% 19% 8%	5192
April	1st to 10th	Night	36% 9% 11% 17% 15% 11%	2000
	11th to 20th	Night	37% 6% 10% 21% 17% 9%	1975
	21st to end	Night	24% 7% 13% 25% 24% 6%	2000
May	1st to 10th	Night	41% 11% 14% 20% 11% 3	4520
	11th to 20th	Night	36% 8% 14% 25% 16% 1	4490
	21st to end	Night	28% 8% 20% 33% 11% 1	4931
June	1st to 10th	Night	29% 11% 19% 27% 13%	2000
	11th to 20th	Night	26% 12% 23% 27% 12%	1923
	21st to end	Night	29% 13% 27% 21% 9%	1800
July	1st to 10th	Night	29% 13% 35% 20% 2	4035
	11th to 20th	Night	23% 16% 49% 11% 1	4260
	21st to end	Night	30% 17% 25% 25% 2	4785
August	1st to 10th	Night	18% 9% 25% 30% 18%	3232
	11th to 20th	Night	23% 13% 32% 29% 3	3230
	21st to end	Night	35% 14% 19% 20% 9% 3	3586
September	1st to 10th	Night	34% 12% 22% 16% 12% 3	1930
	11th to 20th	Night	33% 13% 16% 18% 15% 6%	1943
	21st to end	Night	28% 9% 13% 27% 14% 9%	2090
October	1st to 10th	Night	28% 3 10% 14% 21% 23%	3591
	11th to 20th	Night	16% 3 6% 21% 31% 23%	3779
	21st to end	Night	19% 4 7% 10% 40% 20%	4120
November	1st to 10th	Night	30% 5% 8% 22% 24% 11%	2340
	11th to 20th	Night	31% 5% 8% 18% 26% 13%	2451
	21st to end	Night	34% 6% 8% 21% 21% 10%	2600
December	1st to 10th	Night	41% 5% 8% 19% 22% 6%	4250
	11th to 20th	Night	34% 6% 11% 21% 18% 11%	4627
	21st to end	Night	43% 6% 8% 14% 22% 7%	5984

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% 39% 20% 5% 1	300
	11th to 20th	Day	15% 17% 36% 26% 6%	300
	21st to end	Day	21% 18% 37% 21% 3	330
February	1st to 10th	Day	21% 18% 33% 21% 6% 1	300
	11th to 20th	Day	21% 17% 35% 21% 6%	300
	21st to end	Day	14% 19% 44% 18% 6%	249
March	1st to 10th	Day	19% 16% 33% 29% 3	300
	11th to 20th	Day	17% 18% 38% 22% 4 1	300
	21st to end	Day	14% 13% 34% 27% 11% 1	450
April	1st to 10th	Day	15% 13% 32% 28% 11% 1	500
	11th to 20th	Day	15% 14% 31% 25% 12% 3	492
	21st to end	Day	7% 8% 28% 31% 21% 4	500
May	1st to 10th	Day	11% 7% 24% 31% 23% 3	503
	11th to 20th	Day	10% 4 21% 30% 28% 7%	527
	21st to end	Day	6% 1 14% 34% 29% 15%	573
June	1st to 10th	Day	10% 2 9% 28% 33% 17%	530
	11th to 20th	Day	9% 2 11% 27% 33% 19%	597
	21st to end	Day	7% 2 8% 28% 32% 22%	730
July	1st to 10th	Day	9% 2 9% 21% 34% 26%	721
	11th to 20th	Day	7% 1 4 14% 39% 36%	609
	21st to end	Day	9% 6% 17% 36% 32%	576
August	1st to 10th	Day	5% 2 4 17% 35% 38%	526
	11th to 20th	Day	7% 4 13% 34% 41%	519
	21st to end	Day	9% 3 8% 18% 35% 27%	583
September	1st to 10th	Day	12% 1 8% 20% 35% 23%	502
	11th to 20th	Day	10% 2 12% 21% 38% 17%	490
	21st to end	Day	7% 3 9% 28% 38% 14%	490
October	1st to 10th	Day	7% 5% 18% 38% 27% 4	425
	11th to 20th	Day	5% 4 22% 39% 24% 6%	300
	21st to end	Day	15% 8% 21% 34% 20% 2	330
November	1st to 10th	Day	13% 9% 18% 37% 19% 3	300
	11th to 20th	Day	16% 10% 30% 31% 11% 2	300
	21st to end	Day	13% 13% 34% 31% 8% 1	300
December	1st to 10th	Day	16% 9% 36% 25% 10% 3	300
	11th to 20th	Day	16% 16% 34% 28% 6%	300
	21st to end	Day	23% 12% 30% 25% 9% 1	330
January	1st to 10th	Night	17% 11% 31% 33% 7% 1	842
	11th to 20th	Night	17% 12% 25% 36% 9% 1	814
	21st to end	Night	19% 11% 33% 30% 7%	880
February	1st to 10th	Night	17% 10% 30% 34% 8% 1	800
	11th to 20th	Night	20% 13% 28% 29% 10%	783
	21st to end	Night	19% 12% 33% 30% 6%	660
March	1st to 10th	Night	16% 11% 31% 30% 11%	724
	11th to 20th	Night	14% 7% 28% 34% 15% 1	600
	21st to end	Night	11% 11% 28% 34% 16% 1	660
April	1st to 10th	Night	15% 12% 25% 33% 14% 1	600
	11th to 20th	Night	15% 8% 28% 31% 17% 1	593
	21st to end	Night	8% 6% 22% 39% 23% 2	600
May	1st to 10th	Night	7% 5% 19% 43% 26% 1	600
	11th to 20th	Night	7% 3 17% 41% 28% 3	591
	21st to end	Night	5% 1 13% 33% 38% 10%	650
June	1st to 10th	Night	8% 1 6% 33% 42% 10%	600
	11th to 20th	Night	3 2 5% 26% 49% 15%	600
	21st to end	Night	7% 1 6% 21% 44% 22%	600
July	1st to 10th	Night	6% 1 4 14% 50% 26%	585
	11th to 20th	Night	4 1 2 7% 48% 38%	582
	21st to end	Night	3 3 14% 52% 28%	657
August	1st to 10th	Night	2 2 12% 49% 35%	597
	11th to 20th	Night	6% 2 9% 46% 37%	594
	21st to end	Night	8% 1 4 17% 46% 25%	660
September	1st to 10th	Night	9% 1 4 17% 44% 24%	579
	11th to 20th	Night	8% 3 6% 23% 46% 14%	613
	21st to end	Night	11% 1 9% 29% 39% 10%	760
October	1st to 10th	Night	8% 2 12% 36% 36% 6%	760
	11th to 20th	Night	7% 4 17% 34% 32% 6%	760
	21st to end	Night	10% 7% 18% 35% 27% 3	836
November	1st to 10th	Night	11% 6% 18% 37% 26% 3	780
	11th to 20th	Night	13% 8% 20% 37% 20% 3	800
	21st to end	Night	12% 8% 25% 36% 17% 2	800
December	1st to 10th	Night	15% 10% 25% 31% 18% 2	800
	11th to 20th	Night	17% 7% 27% 36% 14% 1	800
	21st to end	Night	23% 10% 27% 30% 10% 1	880

Page generated at 2025-09-01 00:51:09. Version ac07

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