Jeanerette
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jeanerette clear sky chart from 2005-11-06 to 2025-03-12.

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 7% 5% 5% 5% 5% 7% 8% 38%	109209
	Night	11% 6% 2 6% 4 4 4 4 6% 8% 45%	109917
Transparency	Day	39% 9% 13% 17% 16% 6%	112859
	Night	35% 8% 14% 18% 17% 8%	114407
Seeing	Day	12% 6% 18% 25% 24% 15%	15183
	Night	12% 5% 19% 31% 26% 7%	25043

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	17% 6% 4 7% 4 4 4 3 5% 7% 38%	4077
	11th to 20th	Day	14% 8% 3 7% 3 3 3 3 4 6% 46%	4080
	21st to end	Day	20% 9% 3 7% 4 4 5% 3 4 6% 33%	4502
February	1st to 10th	Day	16% 10% 3 8% 4 4 4 4 5% 6% 37%	2000
	11th to 20th	Day	16% 8% 2 6% 4 4 4 4 6% 6% 40%	1948
	21st to end	Day	17% 10% 3 5% 4 3 4 4 6% 7% 38%	1725
March	1st to 10th	Day	20% 10% 3 8% 5% 5% 5% 4 6% 8% 28%	3546
	11th to 20th	Day	13% 7% 3 8% 6% 5% 5% 5% 8% 9% 32%	3491
	21st to end	Day	11% 6% 2 6% 4 4 4 4 5% 7% 46%	3838
April	1st to 10th	Day	11% 6% 2 6% 5% 5% 4 4 7% 8% 42%	2280
	11th to 20th	Day	14% 6% 2 6% 5% 5% 4 5% 7% 8% 38%	2254
	21st to end	Day	8% 5% 2 5% 4 5% 5% 5% 6% 8% 46%	2280
May	1st to 10th	Day	10% 6% 2 8% 6% 5% 6% 5% 8% 10% 33%	3765
	11th to 20th	Day	10% 5% 2 7% 5% 5% 5% 4 5% 8% 44%	3764
	21st to end	Day	5% 5% 2 5% 5% 5% 6% 6% 8% 11% 42%	4129
June	1st to 10th	Day	7% 4 2 8% 7% 7% 6% 6% 10% 11% 33%	2438
	11th to 20th	Day	5% 4 3 7% 6% 8% 7% 6% 9% 11% 33%	2470
	21st to end	Day	7% 6% 3 8% 8% 8% 9% 7% 9% 10% 25%	2470
July	1st to 10th	Day	5% 6% 3 11% 8% 9% 9% 8% 10% 11% 20%	4120
	11th to 20th	Day	5% 6% 3 10% 8% 8% 9% 6% 9% 11% 24%	4120
	21st to end	Day	9% 9% 4 12% 8% 9% 8% 7% 7% 10% 19%	4350
August	1st to 10th	Day	3 3 1 5% 4 4 5% 5% 8% 11% 50%	3785
	11th to 20th	Day	5% 3 2 6% 5% 6% 7% 6% 10% 15% 35%	3729
	21st to end	Day	10% 8% 4 10% 7% 7% 6% 5% 6% 7% 31%	4180
September	1st to 10th	Day	12% 5% 3 7% 6% 6% 7% 5% 8% 8% 32%	2280
	11th to 20th	Day	11% 7% 3 8% 6% 6% 6% 4 6% 7% 35%	2280
	21st to end	Day	9% 6% 2 6% 5% 4 4 3 6% 7% 47%	2040
October	1st to 10th	Day	6% 4 2 6% 5% 3 4 5% 5% 6% 55%	1900
	11th to 20th	Day	7% 5% 2 5% 3 3 4 3 5% 8% 53%	1900
	21st to end	Day	10% 5% 2 4 4 4 3 3 5% 6% 52%	2090
November	1st to 10th	Day	8% 6% 2 5% 3 4 4 4 7% 8% 50%	1958
	11th to 20th	Day	10% 6% 2 5% 3 4 4 3 5% 5% 54%	2000
	21st to end	Day	12% 5% 2 6% 5% 4 4 4 5% 6% 47%	2000
December	1st to 10th	Day	17% 8% 3 8% 5% 4 3 3 4 5% 40%	3260
	11th to 20th	Day	9% 6% 2 6% 6% 5% 5% 4 5% 7% 46%	3672
	21st to end	Day	13% 7% 3 6% 4 4 4 3 4 6% 46%	4488
January	1st to 10th	Night	17% 6% 3 6% 3 3 3 3 4 5% 46%	5888
	11th to 20th	Night	17% 7% 3 5% 3 3 3 3 4 5% 47%	5900
	21st to end	Night	21% 9% 3 7% 4 5% 4 3 5% 7% 33%	6471
February	1st to 10th	Night	14% 8% 3 6% 5% 4 5% 3 4 6% 41%	2400
	11th to 20th	Night	17% 8% 3 7% 4 3 3 3 5% 5% 41%	2338
	21st to end	Night	17% 9% 2 6% 4 3 4 4 4 6% 41%	1920
March	1st to 10th	Night	22% 11% 3 7% 4 4 3 3 4 6% 32%	3529
	11th to 20th	Night	15% 8% 3 7% 5% 4 5% 4 6% 7% 35%	3497
	21st to end	Night	12% 6% 3 5% 4 4 4 4 6% 7% 45%	3791
April	1st to 10th	Night	13% 6% 2 4 4 5% 4 4 6% 8% 44%	1900
	11th to 20th	Night	12% 6% 2 7% 4 4 4 3 4 5% 49%	1875
	21st to end	Night	7% 4 2 5% 4 4 5% 4 7% 8% 52%	1900
May	1st to 10th	Night	13% 7% 3 6% 5% 5% 4 4 7% 8% 37%	3130
	11th to 20th	Night	15% 5% 2 6% 3 5% 4 4 6% 7% 43%	3129
	21st to end	Night	7% 5% 2 6% 4 4 5% 4 7% 11% 47%	3426
June	1st to 10th	Night	5% 4 2 7% 3 5% 5% 5% 8% 10% 47%	1736
	11th to 20th	Night	4 4 2 4 5% 5% 6% 5% 8% 11% 47%	1710
	21st to end	Night	7% 5% 2 6% 6% 5% 6% 5% 9% 11% 38%	1710
July	1st to 10th	Night	4 5% 2 8% 5% 5% 5% 6% 11% 13% 36%	2850
	11th to 20th	Night	3 3 2 6% 4 5% 6% 6% 9% 13% 43%	2850
	21st to end	Night	3 6% 2 8% 6% 6% 6% 5% 9% 15% 34%	3206
August	1st to 10th	Night	1 2 1 3 3 4 4 4 6% 12% 60%	3144
	11th to 20th	Night	2 2 1 4 3 4 5% 4 8% 16% 50%	3100
	21st to end	Night	6% 5% 3 8% 5% 6% 6% 5% 7% 8% 41%	3476
September	1st to 10th	Night	7% 6% 2 6% 4 5% 5% 4 8% 11% 41%	1900
	11th to 20th	Night	9% 7% 3 7% 4 5% 5% 4 6% 9% 41%	1900
	21st to end	Night	6% 5% 2 6% 4 3 3 4 6% 7% 53%	2115
October	1st to 10th	Night	6% 4 2 5% 4 3 3 3 5% 6% 59%	2280
	11th to 20th	Night	7% 4 1 4 3 3 4 2 5% 7% 60%	2280
	21st to end	Night	9% 4 2 4 3 3 3 3 4 6% 58%	2508
November	1st to 10th	Night	8% 6% 2 5% 4 3 3 4 5% 6% 54%	2340
	11th to 20th	Night	10% 5% 2 5% 3 3 3 3 4 7% 55%	2400
	21st to end	Night	12% 6% 2 6% 3 4 3 4 6% 6% 48%	2400
December	1st to 10th	Night	15% 8% 3 8% 5% 4 4 3 4 6% 40%	3920
	11th to 20th	Night	8% 7% 2 6% 5% 4 4 3 6% 6% 49%	4508
	21st to end	Night	14% 10% 3 7% 3 4 3 2 4 5% 45%	6490

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% 7% 18% 19% 7%	4078
	11th to 20th	Day	40% 4 5% 16% 27% 9%	4080
	21st to end	Day	51% 5% 8% 12% 14% 10%	4502
February	1st to 10th	Day	47% 6% 9% 13% 18% 8%	2000
	11th to 20th	Day	43% 7% 8% 16% 17% 10%	1958
	21st to end	Day	43% 8% 11% 15% 16% 7%	1725
March	1st to 10th	Day	51% 9% 12% 14% 11% 4	3546
	11th to 20th	Day	43% 11% 14% 15% 12% 4	3491
	21st to end	Day	33% 9% 12% 17% 22% 7%	3838
April	1st to 10th	Day	37% 8% 12% 18% 17% 9%	2280
	11th to 20th	Day	39% 8% 13% 19% 14% 8%	2254
	21st to end	Day	31% 9% 13% 21% 21% 5%	2280
May	1st to 10th	Day	38% 14% 16% 19% 10% 3	3800
	11th to 20th	Day	34% 9% 11% 20% 23% 3	3768
	21st to end	Day	28% 13% 18% 31% 10%	4141
June	1st to 10th	Day	38% 13% 15% 23% 11%	2438
	11th to 20th	Day	37% 13% 17% 20% 12% 1	2470
	21st to end	Day	44% 15% 19% 14% 6%	2470
July	1st to 10th	Day	47% 15% 23% 13% 1	4056
	11th to 20th	Day	46% 17% 26% 8% 2	4051
	21st to end	Day	55% 13% 17% 12% 2	4212
August	1st to 10th	Day	23% 12% 15% 31% 19%	3773
	11th to 20th	Day	32% 14% 26% 23% 4	3765
	21st to end	Day	50% 10% 12% 14% 12% 2	4179
September	1st to 10th	Day	42% 14% 16% 16% 9% 3	2280
	11th to 20th	Day	44% 10% 14% 15% 13% 4	2280
	21st to end	Day	36% 7% 11% 22% 16% 9%	2040
October	1st to 10th	Day	26% 4 7% 13% 23% 28%	3160
	11th to 20th	Day	18% 5% 5% 22% 29% 21%	3140
	21st to end	Day	25% 5% 5% 11% 41% 13%	3428
November	1st to 10th	Day	29% 7% 10% 20% 25% 9%	1958
	11th to 20th	Day	32% 4 7% 17% 26% 13%	2000
	21st to end	Day	36% 6% 10% 18% 21% 9%	2000
December	1st to 10th	Day	47% 5% 7% 15% 20% 5%	3260
	11th to 20th	Day	36% 7% 10% 18% 19% 11%	3670
	21st to end	Day	38% 7% 9% 16% 23% 7%	4488
January	1st to 10th	Night	39% 6% 7% 18% 23% 7%	5888
	11th to 20th	Night	39% 4 5% 16% 26% 10%	5900
	21st to end	Night	51% 5% 7% 13% 13% 11%	6471
February	1st to 10th	Night	44% 5% 7% 15% 18% 10%	2400
	11th to 20th	Night	45% 4 8% 15% 17% 11%	2339
	21st to end	Night	43% 7% 11% 14% 15% 11%	1920
March	1st to 10th	Night	51% 7% 11% 14% 11% 6%	3529
	11th to 20th	Night	44% 9% 13% 15% 14% 5%	3497
	21st to end	Night	35% 8% 12% 19% 19% 6%	3791
April	1st to 10th	Night	37% 8% 13% 17% 15% 11%	1900
	11th to 20th	Night	37% 6% 12% 19% 15% 11%	1875
	21st to end	Night	28% 8% 12% 23% 23% 7%	1900
May	1st to 10th	Night	37% 15% 15% 17% 11% 4	3160
	11th to 20th	Night	36% 9% 11% 20% 22% 2	3130
	21st to end	Night	25% 12% 21% 28% 12% 1	3435
June	1st to 10th	Night	28% 11% 23% 25% 13% 1	1736
	11th to 20th	Night	27% 11% 21% 28% 12% 1	1710
	21st to end	Night	35% 12% 24% 23% 7%	1710
July	1st to 10th	Night	33% 16% 36% 13% 2	2805
	11th to 20th	Night	28% 17% 42% 10% 3	2796
	21st to end	Night	36% 17% 27% 17% 3	3104
August	1st to 10th	Night	16% 10% 22% 32% 20%	3132
	11th to 20th	Night	20% 12% 36% 28% 2	3130
	21st to end	Night	38% 11% 17% 20% 13% 2	3476
September	1st to 10th	Night	33% 13% 23% 18% 9% 4	1900
	11th to 20th	Night	37% 11% 18% 17% 14% 4	1900
	21st to end	Night	28% 8% 15% 24% 15% 10%	2115
October	1st to 10th	Night	27% 4 9% 14% 19% 28%	3800
	11th to 20th	Night	15% 5% 6% 20% 32% 22%	3779
	21st to end	Night	19% 4 7% 11% 39% 20%	4120
November	1st to 10th	Night	30% 6% 10% 19% 24% 10%	2340
	11th to 20th	Night	30% 4 8% 17% 27% 14%	2400
	21st to end	Night	36% 6% 8% 19% 22% 11%	2400
December	1st to 10th	Night	45% 4 7% 18% 20% 6%	3920
	11th to 20th	Night	34% 6% 12% 19% 18% 11%	4509
	21st to end	Night	41% 5% 9% 12% 24% 9%	6490

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	21% 14% 36% 20% 6% 2	300
	11th to 20th	Day	16% 14% 37% 26% 6% 1	300
	21st to end	Day	22% 14% 36% 23% 5%	330
February	1st to 10th	Day	21% 10% 30% 28% 11%	300
	11th to 20th	Day	25% 14% 31% 21% 9%	300
	21st to end	Day	14% 16% 49% 16% 4 1	249
March	1st to 10th	Day	17% 15% 37% 24% 8%	300
	11th to 20th	Day	15% 14% 40% 25% 6%	273
	21st to end	Day	13% 16% 38% 24% 9% 1	309
April	1st to 10th	Day	14% 11% 31% 32% 11% 2	460
	11th to 20th	Day	19% 10% 29% 23% 16% 2	452
	21st to end	Day	10% 7% 30% 33% 18% 3	460
May	1st to 10th	Day	10% 7% 25% 36% 19% 3	463
	11th to 20th	Day	10% 3 20% 34% 26% 7%	487
	21st to end	Day	6% 3 12% 33% 32% 13%	529
June	1st to 10th	Day	9% 2 12% 28% 30% 19%	648
	11th to 20th	Day	7% 2 11% 32% 33% 16%	680
	21st to end	Day	10% 3 9% 24% 31% 24%	680
July	1st to 10th	Day	8% 2 5% 22% 35% 29%	671
	11th to 20th	Day	8% 1 4 18% 36% 33%	668
	21st to end	Day	9% 1 5% 16% 39% 29%	673
August	1st to 10th	Day	5% 1 2 12% 37% 44%	486
	11th to 20th	Day	8% 2 11% 34% 45%	479
	21st to end	Day	12% 1 5% 16% 35% 30%	539
September	1st to 10th	Day	12% 3 5% 18% 33% 29%	490
	11th to 20th	Day	13% 2 7% 18% 39% 21%	490
	21st to end	Day	12% 1 8% 22% 36% 21%	407
October	1st to 10th	Day	8% 1 14% 35% 33% 9%	300
	11th to 20th	Day	7% 3 13% 39% 23% 14%	300
	21st to end	Day	17% 8% 18% 30% 21% 7%	330
November	1st to 10th	Day	12% 5% 20% 34% 25% 4	300
	11th to 20th	Day	15% 7% 28% 28% 19% 2	300
	21st to end	Day	12% 12% 31% 27% 13% 4	300
December	1st to 10th	Day	20% 6% 30% 23% 15% 6%	300
	11th to 20th	Day	17% 10% 35% 29% 9%	300
	21st to end	Day	22% 9% 33% 24% 11% 2	330
January	1st to 10th	Night	17% 9% 33% 32% 8% 1	1000
	11th to 20th	Night	17% 10% 31% 32% 9%	1000
	21st to end	Night	20% 9% 33% 30% 8%	1094
February	1st to 10th	Night	17% 9% 32% 36% 7%	800
	11th to 20th	Night	22% 12% 26% 32% 8%	783
	21st to end	Night	20% 11% 36% 29% 5%	600
March	1st to 10th	Night	15% 10% 31% 36% 9%	600
	11th to 20th	Night	12% 6% 31% 38% 13%	575
	21st to end	Night	12% 9% 28% 36% 15%	627
April	1st to 10th	Night	14% 8% 33% 31% 13% 1	570
	11th to 20th	Night	12% 9% 33% 30% 16% 1	563
	21st to end	Night	7% 5% 29% 41% 18% 1	570
May	1st to 10th	Night	11% 4 20% 46% 18% 2	570
	11th to 20th	Night	7% 3 18% 44% 25% 3	561
	21st to end	Night	6% 2 9% 39% 37% 7%	617
June	1st to 10th	Night	6% 2 6% 32% 44% 10%	570
	11th to 20th	Night	4 1 4 27% 51% 13%	570
	21st to end	Night	9% 1 4 22% 46% 17%	570
July	1st to 10th	Night	5% 2 4 12% 54% 23%	555
	11th to 20th	Night	5% 1 3 8% 53% 30%	552
	21st to end	Night	5% 1 4 14% 50% 26%	624
August	1st to 10th	Night	2 2 11% 50% 34%	567
	11th to 20th	Night	4 2 10% 51% 33%	564
	21st to end	Night	8% 1 3 17% 49% 22%	627
September	1st to 10th	Night	7% 3 4 16% 49% 21%	570
	11th to 20th	Night	12% 2 5% 22% 48% 11%	570
	21st to end	Night	7% 1 8% 27% 49% 7%	708
October	1st to 10th	Night	6% 2 11% 35% 39% 6%	760
	11th to 20th	Night	8% 3 17% 37% 31% 4	760
	21st to end	Night	11% 5% 17% 39% 25% 4	836
November	1st to 10th	Night	10% 4 16% 42% 26% 3	780
	11th to 20th	Night	12% 5% 22% 41% 19% 1	800
	21st to end	Night	15% 6% 26% 38% 15% 1	800
December	1st to 10th	Night	17% 7% 24% 33% 18% 1	800
	11th to 20th	Night	16% 8% 25% 39% 11%	830
	21st to end	Night	21% 9% 28% 30% 11%	1100

Page generated at 2025-03-09 07:08:49. Version ac07

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