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 2024-12-24.

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% 3 7% 5% 5% 5% 4 6% 8% 39%	101359
	Night	14% 7% 2 5% 4 4 4 3 5% 7% 45%	98800
Transparency	Day	42% 7% 10% 18% 17% 7%	105005
	Night	37% 6% 11% 19% 18% 9%	103295
Seeing	Day	15% 8% 22% 24% 22% 9%	15112
	Night	16% 8% 23% 30% 20% 3	24944

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	20% 8% 3 6% 4 3 4 3 5% 6% 37%	2847
	11th to 20th	Day	20% 6% 2 5% 3 3 3 2 4 5% 48%	2850
	21st to end	Day	22% 9% 3 7% 4 3 4 3 4 6% 35%	3135
February	1st to 10th	Day	20% 8% 3 7% 4 4 3 4 5% 5% 37%	1710
	11th to 20th	Day	22% 8% 2 6% 4 3 3 3 3 5% 40%	1886
	21st to end	Day	21% 11% 2 5% 4 4 3 4 5% 4 37%	1727
March	1st to 10th	Day	22% 11% 3 8% 6% 5% 4 3 4 5% 27%	3436
	11th to 20th	Day	18% 7% 3 7% 5% 5% 5% 3 6% 8% 31%	3480
	21st to end	Day	16% 8% 3 9% 5% 4 4 3 4 5% 39%	3814
April	1st to 10th	Day	14% 8% 3 6% 5% 4 5% 4 5% 6% 39%	2197
	11th to 20th	Day	17% 8% 3 6% 5% 4 3 4 6% 7% 38%	2254
	21st to end	Day	11% 6% 2 6% 5% 5% 5% 4 6% 8% 41%	2280
May	1st to 10th	Day	17% 9% 3 9% 6% 5% 5% 4 7% 7% 30%	3765
	11th to 20th	Day	13% 6% 2 6% 5% 4 5% 3 5% 7% 43%	3823
	21st to end	Day	9% 6% 3 7% 6% 6% 6% 5% 8% 10% 34%	4477
June	1st to 10th	Day	9% 5% 3 7% 6% 5% 5% 5% 9% 9% 37%	2470
	11th to 20th	Day	5% 6% 2 6% 6% 7% 7% 6% 8% 10% 37%	2470
	21st to end	Day	8% 6% 2 6% 8% 6% 7% 7% 8% 10% 31%	2470
July	1st to 10th	Day	8% 6% 3 8% 8% 6% 7% 6% 8% 12% 28%	4120
	11th to 20th	Day	8% 8% 3 10% 7% 8% 8% 6% 8% 10% 24%	4120
	21st to end	Day	17% 10% 3 9% 7% 5% 5% 4 7% 9% 24%	4465
August	1st to 10th	Day	3 2 1 4 4 5% 5% 4 6% 9% 58%	4016
	11th to 20th	Day	4 3 2 4 4 4 5% 5% 7% 13% 49%	3729
	21st to end	Day	11% 6% 2 7% 6% 5% 6% 5% 7% 8% 36%	4180
September	1st to 10th	Day	11% 6% 2 7% 6% 5% 4 5% 7% 9% 38%	2280
	11th to 20th	Day	14% 6% 2 7% 5% 6% 5% 4 7% 7% 38%	2168
	21st to end	Day	11% 6% 2 4 4 4 5% 3 6% 7% 49%	2028
October	1st to 10th	Day	7% 4 2 5% 4 3 3 4 4 6% 57%	1900
	11th to 20th	Day	10% 4 2 4 4 4 4 4 5% 6% 53%	1900
	21st to end	Day	13% 5% 2 5% 3 3 3 3 4 5% 52%	2090
November	1st to 10th	Day	13% 7% 2 6% 4 4 4 4 5% 6% 47%	1958
	11th to 20th	Day	12% 6% 2 6% 5% 3 3 3 4 5% 52%	2000
	21st to end	Day	17% 8% 2 6% 3 4 3 2 4 5% 45%	2000
December	1st to 10th	Day	18% 9% 3 5% 4 3 3 3 5% 5% 42%	1901
	11th to 20th	Day	18% 9% 3 6% 5% 4 4 3 4 6% 39%	2251
	21st to end	Day	17% 8% 3 6% 4 3 4 2 4 6% 42%	3162
January	1st to 10th	Night	16% 7% 4 5% 3 3 3 2 4 6% 46%	4108
	11th to 20th	Night	17% 7% 2 5% 3 3 3 2 3 4 50%	4120
	21st to end	Night	25% 10% 2 5% 3 3 3 2 4 7% 38%	4532
February	1st to 10th	Night	18% 8% 3 6% 4 4 4 3 5% 6% 40%	2470
	11th to 20th	Night	23% 8% 2 5% 4 2 3 3 3 5% 42%	2192
	21st to end	Night	24% 8% 3 6% 4 3 3 3 4 5% 36%	1727
March	1st to 10th	Night	25% 11% 3 7% 4 4 4 3 4 5% 30%	3419
	11th to 20th	Night	21% 9% 3 7% 5% 4 4 3 5% 6% 34%	3480
	21st to end	Night	14% 7% 2 5% 4 5% 5% 4 6% 7% 42%	3817
April	1st to 10th	Night	16% 6% 2 5% 4 4 5% 4 4 8% 42%	1981
	11th to 20th	Night	16% 6% 2 5% 3 3 4 3 5% 7% 45%	1875
	21st to end	Night	12% 5% 2 6% 4 3 4 4 6% 7% 48%	1900
May	1st to 10th	Night	20% 10% 3 7% 5% 4 5% 4 5% 7% 30%	3130
	11th to 20th	Night	15% 7% 2 6% 5% 3 4 3 5% 7% 44%	3055
	21st to end	Night	12% 7% 2 7% 4 4 4 5% 7% 9% 37%	3090
June	1st to 10th	Night	6% 5% 2 5% 4 4 4 4 8% 8% 50%	1710
	11th to 20th	Night	4 4 1 4 4 4 4 4 6% 12% 53%	1710
	21st to end	Night	6% 4 2 5% 5% 5% 5% 4 9% 10% 45%	1710
July	1st to 10th	Night	5% 6% 2 6% 5% 5% 5% 5% 8% 12% 41%	2850
	11th to 20th	Night	6% 5% 2 6% 5% 5% 6% 6% 9% 11% 39%	2850
	21st to end	Night	12% 9% 3 7% 5% 5% 5% 4 7% 10% 33%	3098
August	1st to 10th	Night	2 2 1 3 2 3 3 3 6% 10% 67%	2918
	11th to 20th	Night	3 2 1 3 2 3 4 4 9% 13% 56%	3100
	21st to end	Night	8% 5% 2 6% 5% 4 6% 6% 8% 8% 41%	3476
September	1st to 10th	Night	9% 5% 2 6% 4 4 4 4 7% 10% 46%	1900
	11th to 20th	Night	11% 6% 2 6% 5% 4 4 4 7% 7% 44%	2005
	21st to end	Night	9% 5% 2 5% 3 3 4 2 5% 6% 55%	2131
October	1st to 10th	Night	5% 4 1 4 4 3 5% 3 5% 7% 58%	2280
	11th to 20th	Night	10% 5% 1 4 3 3 4 3 4 6% 57%	2280
	21st to end	Night	12% 5% 2 4 3 3 3 2 4 5% 59%	2508
November	1st to 10th	Night	11% 5% 2 4 3 4 4 3 4 7% 53%	2340
	11th to 20th	Night	11% 5% 2 4 3 3 3 2 5% 7% 54%	2400
	21st to end	Night	15% 8% 3 5% 4 4 4 3 5% 5% 45%	2400
December	1st to 10th	Night	20% 8% 2 5% 4 3 4 3 4 5% 42%	2494
	11th to 20th	Night	16% 10% 2 6% 4 3 3 3 4 5% 44%	3166
	21st to end	Night	18% 10% 2 5% 3 3 3 3 5% 6% 42%	4578

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	45% 5% 5% 19% 19% 8%	2848
	11th to 20th	Day	39% 3 5% 17% 27% 10%	2850
	21st to end	Day	51% 3 4 14% 18% 9%	3135
February	1st to 10th	Day	49% 4 6% 14% 18% 9%	1710
	11th to 20th	Day	49% 5% 5% 14% 17% 10%	1896
	21st to end	Day	50% 5% 6% 12% 16% 10%	1727
March	1st to 10th	Day	59% 5% 6% 13% 12% 5%	3436
	11th to 20th	Day	50% 6% 8% 18% 14% 5%	3480
	21st to end	Day	48% 4 7% 15% 22% 4	3814
April	1st to 10th	Day	44% 6% 8% 16% 18% 8%	2197
	11th to 20th	Day	45% 5% 9% 16% 15% 10%	2254
	21st to end	Day	39% 6% 9% 18% 22% 5%	2280
May	1st to 10th	Day	51% 8% 10% 18% 10% 4	3800
	11th to 20th	Day	39% 7% 9% 19% 24% 3	3827
	21st to end	Day	40% 10% 13% 25% 10% 1	4489
June	1st to 10th	Day	41% 9% 15% 20% 14% 1	2470
	11th to 20th	Day	39% 10% 13% 23% 14% 2	2470
	21st to end	Day	42% 13% 16% 18% 10%	2470
July	1st to 10th	Day	45% 12% 21% 18% 4	4056
	11th to 20th	Day	50% 11% 18% 16% 5%	4051
	21st to end	Day	55% 9% 14% 18% 4 1	4325
August	1st to 10th	Day	21% 9% 13% 34% 23%	4002
	11th to 20th	Day	25% 9% 25% 35% 6% 1	3765
	21st to end	Day	44% 9% 13% 16% 17% 1	4179
September	1st to 10th	Day	40% 10% 13% 17% 14% 6%	2280
	11th to 20th	Day	44% 7% 13% 15% 17% 6%	2168
	21st to end	Day	33% 7% 11% 21% 17% 10%	2028
October	1st to 10th	Day	20% 4 6% 13% 22% 35%	3160
	11th to 20th	Day	20% 3 3 18% 30% 25%	3140
	21st to end	Day	27% 4 3 11% 39% 17%	3428
November	1st to 10th	Day	39% 5% 6% 17% 22% 11%	1958
	11th to 20th	Day	36% 4 6% 15% 28% 13%	2000
	21st to end	Day	42% 4 7% 17% 22% 8%	2000
December	1st to 10th	Day	44% 4 8% 19% 17% 8%	1901
	11th to 20th	Day	47% 4 5% 13% 21% 9%	2249
	21st to end	Day	44% 4 5% 15% 25% 7%	3162
January	1st to 10th	Night	40% 4 4 19% 26% 8%	4108
	11th to 20th	Night	39% 3 4 18% 26% 10%	4120
	21st to end	Night	49% 4 5% 16% 17% 9%	4532
February	1st to 10th	Night	47% 3 5% 15% 18% 12%	2470
	11th to 20th	Night	46% 4 5% 15% 20% 10%	2193
	21st to end	Night	51% 4 6% 11% 15% 12%	1727
March	1st to 10th	Night	56% 5% 7% 12% 13% 6%	3419
	11th to 20th	Night	51% 6% 8% 14% 15% 5%	3480
	21st to end	Night	40% 6% 9% 17% 22% 6%	3817
April	1st to 10th	Night	40% 6% 10% 17% 17% 10%	1981
	11th to 20th	Night	39% 5% 11% 18% 15% 12%	1875
	21st to end	Night	35% 6% 10% 19% 23% 7%	1900
May	1st to 10th	Night	52% 8% 10% 14% 11% 4	3160
	11th to 20th	Night	40% 6% 10% 17% 24% 3	3056
	21st to end	Night	40% 10% 17% 21% 10% 1	3099
June	1st to 10th	Night	28% 9% 20% 26% 16% 1	1710
	11th to 20th	Night	24% 8% 18% 33% 15% 3	1710
	21st to end	Night	30% 11% 22% 26% 11% 1	1710
July	1st to 10th	Night	33% 13% 32% 18% 4	2805
	11th to 20th	Night	34% 13% 27% 22% 4	2796
	21st to end	Night	45% 11% 21% 18% 6%	2999
August	1st to 10th	Night	13% 6% 20% 36% 25%	2908
	11th to 20th	Night	17% 11% 31% 34% 7% 1	3130
	21st to end	Night	37% 12% 15% 19% 16% 2	3476
September	1st to 10th	Night	32% 10% 17% 23% 13% 6%	1900
	11th to 20th	Night	37% 9% 14% 19% 15% 7%	2005
	21st to end	Night	29% 5% 12% 22% 19% 13%	2131
October	1st to 10th	Night	18% 5% 7% 15% 18% 37%	3800
	11th to 20th	Night	18% 3 3 21% 30% 25%	3779
	21st to end	Night	22% 3 4 12% 37% 21%	4120
November	1st to 10th	Night	32% 5% 9% 18% 23% 12%	2340
	11th to 20th	Night	31% 4 9% 16% 25% 15%	2400
	21st to end	Night	41% 4 7% 16% 22% 11%	2400
December	1st to 10th	Night	45% 4 7% 18% 18% 8%	2494
	11th to 20th	Night	44% 3 5% 13% 22% 13%	3167
	21st to end	Night	43% 5% 6% 16% 23% 7%	4578

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	24% 17% 40% 14% 5%	270
	11th to 20th	Day	27% 16% 34% 16% 6% 1	270
	21st to end	Day	28% 24% 30% 14% 3	297
February	1st to 10th	Day	27% 19% 33% 17% 3 1	270
	11th to 20th	Day	37% 17% 30% 14% 2	270
	21st to end	Day	32% 24% 35% 9%	225
March	1st to 10th	Day	28% 18% 34% 15% 5%	270
	11th to 20th	Day	20% 25% 36% 15% 4	270
	21st to end	Day	22% 21% 40% 13% 5%	297
April	1st to 10th	Day	21% 18% 34% 22% 5%	377
	11th to 20th	Day	29% 14% 25% 20% 11% 1	452
	21st to end	Day	15% 13% 35% 23% 13% 1	460
May	1st to 10th	Day	18% 11% 33% 24% 13% 1	463
	11th to 20th	Day	12% 8% 25% 32% 19% 5%	520
	21st to end	Day	9% 6% 28% 32% 19% 7%	734
June	1st to 10th	Day	8% 3 17% 33% 28% 11%	680
	11th to 20th	Day	6% 4 17% 34% 30% 10%	680
	21st to end	Day	10% 3 13% 27% 31% 16%	680
July	1st to 10th	Day	8% 2 10% 27% 36% 18%	671
	11th to 20th	Day	6% 1 8% 25% 40% 20%	668
	21st to end	Day	9% 1 8% 26% 40% 16%	739
August	1st to 10th	Day	5% 1 6% 19% 46% 23%	627
	11th to 20th	Day	6% 4 18% 44% 29%	479
	21st to end	Day	12% 3 8% 21% 32% 25%	539
September	1st to 10th	Day	10% 2 7% 28% 34% 19%	490
	11th to 20th	Day	13% 2 11% 29% 29% 15%	378
	21st to end	Day	14% 2 13% 30% 30% 11%	300
October	1st to 10th	Day	7% 6% 22% 39% 20% 6%	300
	11th to 20th	Day	9% 5% 28% 34% 17% 6%	300
	21st to end	Day	21% 11% 20% 30% 13% 6%	330
November	1st to 10th	Day	17% 10% 24% 33% 13% 3	300
	11th to 20th	Day	15% 13% 34% 29% 9%	300
	21st to end	Day	21% 17% 35% 19% 8% 1	300
December	1st to 10th	Day	22% 15% 34% 18% 9% 2	300
	11th to 20th	Day	22% 14% 38% 21% 4 1	300
	21st to end	Day	27% 16% 35% 14% 6% 1	306
January	1st to 10th	Night	24% 13% 32% 25% 6%	950
	11th to 20th	Night	24% 12% 31% 25% 8%	950
	21st to end	Night	25% 12% 31% 28% 4	1045
February	1st to 10th	Night	24% 14% 34% 24% 4	950
	11th to 20th	Night	30% 13% 30% 22% 5%	717
	21st to end	Night	29% 14% 32% 23% 2	471
March	1st to 10th	Night	24% 12% 29% 29% 5%	570
	11th to 20th	Night	20% 12% 35% 27% 6% 1	570
	21st to end	Night	17% 11% 36% 28% 8%	627
April	1st to 10th	Night	17% 12% 38% 27% 7%	570
	11th to 20th	Night	19% 12% 31% 27% 10% 1	563
	21st to end	Night	13% 10% 34% 29% 12% 1	570
May	1st to 10th	Night	14% 9% 32% 33% 12%	570
	11th to 20th	Night	13% 4 31% 34% 17% 1	561
	21st to end	Night	8% 4 21% 38% 26% 4	617
June	1st to 10th	Night	7% 2 10% 38% 37% 5%	570
	11th to 20th	Night	6% 3 12% 45% 30% 4	570
	21st to end	Night	7% 1 9% 30% 43% 9%	570
July	1st to 10th	Night	5% 2 6% 34% 41% 12%	555
	11th to 20th	Night	5% 1 6% 32% 43% 13%	552
	21st to end	Night	6% 2 5% 31% 46% 10%	624
August	1st to 10th	Night	3 5% 31% 49% 11%	567
	11th to 20th	Night	5% 1 4 28% 52% 11%	564
	21st to end	Night	10% 1 6% 23% 46% 14%	627
September	1st to 10th	Night	11% 1 7% 29% 44% 9%	570
	11th to 20th	Night	13% 1 9% 25% 44% 8%	570
	21st to end	Night	11% 2 11% 30% 41% 5%	611
October	1st to 10th	Night	7% 1 14% 34% 38% 4	760
	11th to 20th	Night	12% 4 23% 38% 21% 2	760
	21st to end	Night	13% 9% 20% 35% 21% 2	836
November	1st to 10th	Night	12% 7% 23% 34% 21% 2	780
	11th to 20th	Night	14% 8% 26% 36% 15% 1	800
	21st to end	Night	19% 10% 30% 28% 13% 1	800
December	1st to 10th	Night	23% 11% 26% 30% 10%	894
	11th to 20th	Night	25% 11% 29% 28% 7%	1000
	21st to end	Night	26% 11% 27% 29% 7%	1063

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