DeRidder
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the DeRidder clear sky chart from 2005-11-06 to 2026-04-17.

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	13% 7% 2 7% 5% 4 5% 4 6% 7% 40%	131484
	Night	15% 7% 2 5% 4 4 4 3 5% 7% 45%	130908
Transparency	Day	41% 7% 11% 18% 17% 7%	135091
	Night	38% 6% 11% 19% 18% 9%	135379
Seeing	Day	15% 9% 22% 25% 21% 9%	16805
	Night	16% 8% 23% 30% 20% 3	26694

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	18% 9% 3 6% 4 3 3 3 4 5% 41%	5289
	11th to 20th	Day	13% 5% 2 6% 3 4 4 3 5% 6% 51%	5310
	21st to end	Day	25% 9% 3 7% 4 4 4 3 4 4 34%	5812
February	1st to 10th	Day	19% 8% 3 7% 4 3 3 3 5% 5% 39%	1890
	11th to 20th	Day	22% 9% 3 6% 4 3 3 3 4 5% 38%	2091
	21st to end	Day	21% 11% 2 6% 4 4 3 4 5% 4 37%	1903
March	1st to 10th	Day	20% 10% 3 8% 5% 4 4 3 4 5% 34%	5046
	11th to 20th	Day	14% 6% 2 6% 4 4 4 3 4 6% 46%	5090
	21st to end	Day	16% 8% 3 8% 5% 4 4 3 4 5% 40%	5583
April	1st to 10th	Day	14% 8% 3 7% 5% 5% 5% 4 5% 7% 38%	2429
	11th to 20th	Day	16% 8% 3 6% 5% 4 3 4 6% 7% 39%	2446
	21st to end	Day	12% 6% 2 7% 5% 5% 5% 4 6% 8% 40%	2400
May	1st to 10th	Day	18% 8% 3 8% 5% 5% 5% 4 7% 7% 29%	5405
	11th to 20th	Day	12% 6% 3 7% 5% 5% 5% 4 6% 8% 40%	5491
	21st to end	Day	10% 6% 3 7% 5% 5% 5% 5% 7% 10% 37%	6434
June	1st to 10th	Day	9% 5% 3 7% 6% 5% 6% 5% 9% 9% 37%	2600
	11th to 20th	Day	6% 6% 2 6% 6% 7% 7% 6% 8% 10% 36%	2600
	21st to end	Day	8% 6% 2 6% 8% 6% 7% 7% 8% 10% 32%	2600
July	1st to 10th	Day	7% 6% 3 7% 6% 6% 7% 6% 8% 13% 32%	5900
	11th to 20th	Day	8% 7% 3 8% 6% 7% 8% 5% 8% 11% 30%	5900
	21st to end	Day	12% 7% 2 8% 6% 5% 5% 4 7% 10% 32%	6422
August	1st to 10th	Day	3 2 1 3 4 5% 5% 4 6% 9% 58%	4143
	11th to 20th	Day	4 3 2 4 4 4 5% 5% 8% 13% 49%	3849
	21st to end	Day	11% 6% 2 7% 5% 5% 6% 5% 7% 8% 36%	4312
September	1st to 10th	Day	10% 6% 2 6% 6% 5% 4 5% 7% 9% 40%	2400
	11th to 20th	Day	13% 6% 2 6% 5% 5% 5% 4 7% 7% 39%	2282
	21st to end	Day	10% 6% 2 4 4 4 5% 3 6% 7% 49%	2135
October	1st to 10th	Day	7% 4 2 5% 4 3 3 4 5% 6% 58%	2000
	11th to 20th	Day	9% 4 2 4 4 4 4 4 5% 6% 54%	2000
	21st to end	Day	13% 5% 2 5% 3 3 3 3 4 5% 53%	2200
November	1st to 10th	Day	12% 7% 2 5% 4 4 4 3 5% 5% 48%	2058
	11th to 20th	Day	12% 6% 2 5% 4 3 3 3 4 5% 52%	2100
	21st to end	Day	17% 8% 2 6% 4 4 3 2 5% 6% 44%	2100
December	1st to 10th	Day	21% 8% 3 5% 3 3 3 2 4 4 43%	3196
	11th to 20th	Day	16% 9% 3 6% 5% 4 4 3 4 5% 40%	3481
	21st to end	Day	17% 7% 3 6% 3 3 3 2 3 6% 46%	4587
January	1st to 10th	Night	18% 6% 3 5% 3 3 3 2 4 5% 49%	7634
	11th to 20th	Night	14% 8% 2 5% 4 3 3 2 4 5% 50%	7680
	21st to end	Night	28% 9% 3 7% 3 3 3 2 3 5% 34%	8402
February	1st to 10th	Night	18% 8% 3 6% 4 3 3 3 5% 6% 41%	2730
	11th to 20th	Night	23% 8% 2 5% 4 2 3 3 4 5% 41%	2428
	21st to end	Night	23% 8% 3 6% 4 3 3 3 4 5% 38%	1903
March	1st to 10th	Night	22% 9% 3 6% 3 3 4 3 4 5% 38%	5029
	11th to 20th	Night	20% 8% 2 5% 4 3 3 2 4 5% 44%	5090
	21st to end	Night	18% 7% 3 5% 4 4 4 3 5% 5% 42%	5588
April	1st to 10th	Night	17% 6% 3 5% 4 4 5% 4 4 7% 41%	2189
	11th to 20th	Night	16% 6% 2 5% 3 3 4 3 5% 7% 46%	2035
	21st to end	Night	12% 5% 2 6% 5% 4 4 4 6% 6% 48%	2000
May	1st to 10th	Night	19% 10% 3 7% 5% 4 4 3 6% 8% 30%	4490
	11th to 20th	Night	17% 7% 2 6% 4 4 4 3 5% 7% 41%	4389
	21st to end	Night	15% 8% 2 7% 4 5% 4 4 7% 9% 35%	4443
June	1st to 10th	Night	6% 5% 2 5% 4 4 4 4 7% 8% 50%	1800
	11th to 20th	Night	4 3 1 5% 4 4 4 4 6% 12% 53%	1800
	21st to end	Night	6% 3 2 5% 6% 5% 5% 4 9% 10% 46%	1800
July	1st to 10th	Night	4 6% 2 6% 5% 5% 5% 5% 9% 14% 40%	4078
	11th to 20th	Night	5% 4 2 6% 4 4 5% 5% 8% 12% 44%	4077
	21st to end	Night	10% 7% 3 7% 5% 5% 5% 4 6% 9% 39%	4449
August	1st to 10th	Night	2 2 1 3 2 3 3 3 5% 10% 67%	3011
	11th to 20th	Night	2 2 1 3 2 3 5% 4 9% 13% 56%	3200
	21st to end	Night	9% 5% 2 6% 5% 4 6% 6% 8% 8% 41%	3586
September	1st to 10th	Night	8% 5% 2 6% 4 4 5% 4 6% 10% 47%	2000
	11th to 20th	Night	11% 5% 2 5% 5% 4 5% 4 7% 7% 45%	2111
	21st to end	Night	8% 5% 2 5% 3 3 4 2 5% 7% 56%	2243
October	1st to 10th	Night	5% 4 1 4 4 3 4 3 5% 7% 59%	2400
	11th to 20th	Night	9% 4 1 4 3 3 3 3 4 6% 59%	2400
	21st to end	Night	12% 5% 2 4 3 3 3 2 4 5% 59%	2640
November	1st to 10th	Night	11% 5% 2 4 3 3 4 3 3 6% 54%	2460
	11th to 20th	Night	11% 5% 1 4 3 3 3 2 5% 7% 55%	2520
	21st to end	Night	16% 8% 3 5% 4 4 4 3 5% 5% 45%	2520
December	1st to 10th	Night	22% 8% 2 7% 4 3 3 2 3 5% 39%	4204
	11th to 20th	Night	16% 10% 2 6% 4 3 3 3 4 5% 44%	4946
	21st to end	Night	16% 10% 2 5% 3 3 3 3 4 5% 47%	6633

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	44% 4 5% 23% 19% 5%	5290
	11th to 20th	Day	35% 3 5% 17% 29% 11%	5310
	21st to end	Day	54% 3 4 11% 16% 11%	5812
February	1st to 10th	Day	47% 4 6% 15% 18% 10%	1890
	11th to 20th	Day	49% 5% 6% 15% 16% 9%	2101
	21st to end	Day	50% 5% 6% 12% 17% 10%	1903
March	1st to 10th	Day	53% 4 5% 10% 16% 11%	5046
	11th to 20th	Day	40% 5% 6% 14% 20% 16%	5090
	21st to end	Day	46% 5% 8% 19% 17% 5%	5585
April	1st to 10th	Day	44% 6% 8% 16% 17% 8%	2429
	11th to 20th	Day	44% 5% 10% 16% 17% 9%	2446
	21st to end	Day	40% 6% 10% 18% 21% 5%	2400
May	1st to 10th	Day	50% 8% 10% 20% 10% 3	5440
	11th to 20th	Day	40% 7% 14% 19% 18% 2	5495
	21st to end	Day	39% 8% 13% 25% 13% 2	6447
June	1st to 10th	Day	40% 9% 15% 20% 14% 1	2600
	11th to 20th	Day	39% 10% 13% 23% 14% 2	2600
	21st to end	Day	41% 13% 17% 19% 10%	2600
July	1st to 10th	Day	41% 12% 25% 19% 3	5836
	11th to 20th	Day	44% 11% 23% 19% 4	5831
	21st to end	Day	44% 10% 15% 25% 5%	6240
August	1st to 10th	Day	21% 9% 13% 35% 23%	4129
	11th to 20th	Day	25% 9% 26% 35% 6% 1	3885
	21st to end	Day	44% 9% 13% 16% 17% 1	4311
September	1st to 10th	Day	38% 11% 14% 17% 15% 6%	2400
	11th to 20th	Day	42% 7% 12% 17% 17% 5%	2282
	21st to end	Day	33% 7% 11% 21% 18% 10%	2135
October	1st to 10th	Day	20% 4 6% 13% 23% 34%	3260
	11th to 20th	Day	20% 3 3 18% 30% 25%	3240
	21st to end	Day	27% 4 3 11% 38% 16%	3538
November	1st to 10th	Day	38% 5% 6% 17% 23% 11%	2058
	11th to 20th	Day	35% 4 6% 16% 27% 12%	2100
	21st to end	Day	42% 4 7% 18% 22% 8%	2100
December	1st to 10th	Day	47% 3 5% 16% 24% 5%	3196
	11th to 20th	Day	46% 4 5% 11% 23% 10%	3479
	21st to end	Day	42% 3 5% 17% 26% 8%	4587
January	1st to 10th	Night	38% 4 7% 22% 23% 6%	7635
	11th to 20th	Night	38% 3 4 16% 27% 12%	7680
	21st to end	Night	55% 3 4 13% 15% 10%	8402
February	1st to 10th	Night	46% 3 5% 15% 19% 12%	2730
	11th to 20th	Night	46% 4 6% 15% 19% 9%	2429
	21st to end	Night	50% 4 6% 11% 15% 12%	1903
March	1st to 10th	Night	49% 4 6% 11% 18% 11%	5029
	11th to 20th	Night	44% 5% 6% 13% 14% 17%	5090
	21st to end	Night	44% 5% 7% 17% 20% 7%	5588
April	1st to 10th	Night	42% 6% 10% 16% 16% 10%	2189
	11th to 20th	Night	38% 5% 12% 18% 15% 12%	2035
	21st to end	Night	35% 6% 11% 19% 22% 7%	2000
May	1st to 10th	Night	51% 7% 10% 18% 11% 3	4520
	11th to 20th	Night	42% 7% 12% 18% 20% 2	4390
	21st to end	Night	43% 10% 16% 21% 10% 1	4452
June	1st to 10th	Night	28% 9% 20% 26% 16% 1	1800
	11th to 20th	Night	24% 9% 18% 32% 14% 3	1800
	21st to end	Night	29% 11% 22% 27% 10% 1	1800
July	1st to 10th	Night	31% 12% 34% 19% 3	4035
	11th to 20th	Night	30% 13% 30% 25% 3	4026
	21st to end	Night	40% 10% 17% 25% 7%	4320
August	1st to 10th	Night	13% 6% 20% 36% 25%	3001
	11th to 20th	Night	17% 11% 31% 34% 7% 1	3230
	21st to end	Night	37% 12% 15% 19% 16% 2	3586
September	1st to 10th	Night	31% 10% 17% 22% 14% 6%	2000
	11th to 20th	Night	36% 9% 14% 20% 15% 6%	2111
	21st to end	Night	28% 5% 13% 22% 19% 13%	2243
October	1st to 10th	Night	18% 5% 7% 15% 19% 37%	3920
	11th to 20th	Night	17% 3 3 22% 30% 25%	3899
	21st to end	Night	22% 3 4 13% 37% 21%	4252
November	1st to 10th	Night	32% 5% 9% 18% 24% 12%	2460
	11th to 20th	Night	30% 4 9% 18% 24% 15%	2520
	21st to end	Night	41% 4 7% 16% 22% 10%	2520
December	1st to 10th	Night	50% 3 5% 14% 23% 5%	4204
	11th to 20th	Night	43% 3 6% 13% 22% 11%	4947
	21st to end	Night	41% 4 5% 16% 26% 7%	6633

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	23% 18% 38% 17% 5%	330
	11th to 20th	Day	26% 15% 36% 16% 6% 1	330
	21st to end	Day	29% 25% 29% 15% 3	363
February	1st to 10th	Day	24% 18% 37% 18% 3 1	330
	11th to 20th	Day	35% 18% 29% 14% 3	330
	21st to end	Day	29% 25% 35% 10% 1	273
March	1st to 10th	Day	27% 18% 35% 17% 5%	330
	11th to 20th	Day	20% 25% 36% 15% 5%	330
	21st to end	Day	20% 18% 37% 17% 7% 1	363
April	1st to 10th	Day	21% 18% 33% 23% 5%	449
	11th to 20th	Day	27% 14% 27% 21% 10% 1	516
	21st to end	Day	15% 13% 34% 23% 13% 2	500
May	1st to 10th	Day	18% 12% 33% 24% 12% 1	503
	11th to 20th	Day	13% 8% 27% 30% 17% 4	562
	21st to end	Day	9% 6% 29% 32% 18% 6%	789
June	1st to 10th	Day	8% 3 17% 34% 28% 10%	730
	11th to 20th	Day	6% 4 17% 34% 30% 9%	730
	21st to end	Day	10% 3 12% 27% 31% 17%	730
July	1st to 10th	Day	8% 2 10% 26% 37% 17%	721
	11th to 20th	Day	6% 1 8% 26% 39% 20%	718
	21st to end	Day	9% 2 7% 25% 40% 17%	794
August	1st to 10th	Day	5% 1 6% 19% 47% 23%	674
	11th to 20th	Day	6% 3 17% 44% 30%	519
	21st to end	Day	13% 3 7% 20% 33% 24%	583
September	1st to 10th	Day	10% 2 7% 30% 34% 18%	530
	11th to 20th	Day	12% 2 10% 27% 32% 16%	412
	21st to end	Day	14% 2 13% 32% 29% 10%	330
October	1st to 10th	Day	6% 5% 21% 41% 20% 6%	330
	11th to 20th	Day	8% 5% 27% 35% 18% 7%	330
	21st to end	Day	21% 10% 20% 30% 13% 6%	363
November	1st to 10th	Day	16% 10% 23% 32% 15% 4	330
	11th to 20th	Day	14% 12% 34% 30% 9% 1	330
	21st to end	Day	20% 16% 36% 19% 8% 1	330
December	1st to 10th	Day	24% 15% 34% 18% 8% 2	330
	11th to 20th	Day	21% 13% 38% 22% 6% 1	330
	21st to end	Day	26% 16% 35% 15% 8% 1	363
January	1st to 10th	Night	24% 13% 32% 25% 6%	1050
	11th to 20th	Night	23% 13% 31% 24% 7%	1050
	21st to end	Night	26% 12% 30% 27% 4	1155
February	1st to 10th	Night	24% 13% 34% 24% 4	1050
	11th to 20th	Night	30% 14% 29% 22% 5%	793
	21st to end	Night	28% 13% 33% 24% 3	519
March	1st to 10th	Night	25% 13% 30% 28% 5%	630
	11th to 20th	Night	21% 12% 34% 26% 6% 1	630
	21st to end	Night	18% 11% 35% 29% 8%	693
April	1st to 10th	Night	19% 11% 36% 27% 6%	630
	11th to 20th	Night	18% 12% 30% 28% 10%	611
	21st to end	Night	13% 11% 33% 30% 13% 1	600
May	1st to 10th	Night	15% 9% 31% 33% 12%	600
	11th to 20th	Night	13% 5% 31% 33% 17% 1	591
	21st to end	Night	9% 4 21% 38% 25% 4	650
June	1st to 10th	Night	7% 2 10% 40% 36% 5%	600
	11th to 20th	Night	6% 3 13% 45% 31% 3	600
	21st to end	Night	7% 1 9% 29% 45% 9%	600
July	1st to 10th	Night	4 2 6% 34% 42% 11%	585
	11th to 20th	Night	5% 1 6% 31% 44% 12%	582
	21st to end	Night	6% 2 5% 31% 46% 10%	657
August	1st to 10th	Night	3 5% 30% 50% 11%	597
	11th to 20th	Night	5% 1 4 27% 51% 13%	594
	21st to end	Night	11% 1 7% 22% 46% 14%	660
September	1st to 10th	Night	11% 1 7% 31% 43% 8%	600
	11th to 20th	Night	12% 1 9% 24% 46% 8%	600
	21st to end	Night	11% 2 10% 31% 41% 5%	643
October	1st to 10th	Night	7% 2 15% 34% 39% 5%	800
	11th to 20th	Night	11% 4 23% 38% 22% 3	800
	21st to end	Night	13% 9% 20% 36% 20% 2	880
November	1st to 10th	Night	12% 7% 23% 35% 21% 3	820
	11th to 20th	Night	13% 8% 25% 38% 15%	840
	21st to end	Night	19% 10% 30% 29% 12% 1	840
December	1st to 10th	Night	24% 11% 26% 30% 10%	939
	11th to 20th	Night	24% 11% 29% 29% 7%	1050
	21st to end	Night	26% 11% 27% 29% 6%	1155

Page generated at 2026-04-14 01:44:28. Version ac07

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