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 2024-01-16.

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% 6% 3 5% 6% 3 5% 5% 6% 8% 39%	75055
	Night	13% 6% 2 4 4 3 4 4 5% 8% 47%	74772
Transparency	Day	42% 7% 10% 18% 17% 6%	74780
	Night	36% 6% 12% 19% 18% 8%	74568
Seeing	Day	15% 8% 21% 25% 22% 9%	13841
	Night	16% 7% 23% 30% 21% 3	23751

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% 7% 2 5% 3 3 4 4 5% 6% 42%	1707
	11th to 20th	Day	20% 6% 3 5% 4 3 3 3 4 5% 43%	1670
	21st to end	Day	20% 7% 4 6% 5% 2 3 3 4 4 41%	1782
February	1st to 10th	Day	20% 8% 4 6% 5% 2 3 5% 4 5% 38%	1620
	11th to 20th	Day	23% 8% 3 5% 5% 2 3 4 4 5% 39%	1784
	21st to end	Day	22% 10% 3 5% 4 3 3 5% 5% 4 35%	1628
March	1st to 10th	Day	22% 8% 3 6% 6% 2 4 4 3 6% 36%	1980
	11th to 20th	Day	17% 7% 3 6% 6% 3 5% 4 5% 7% 37%	1980
	21st to end	Day	14% 7% 3 6% 5% 4 5% 4 4 6% 42%	2178
April	1st to 10th	Day	13% 7% 3 5% 6% 3 5% 5% 5% 7% 39%	2081
	11th to 20th	Day	17% 7% 3 5% 5% 3 4 5% 6% 7% 38%	2134
	21st to end	Day	12% 6% 2 6% 6% 4 5% 6% 6% 8% 42%	2160
May	1st to 10th	Day	12% 6% 3 6% 6% 3 5% 5% 7% 8% 39%	2160
	11th to 20th	Day	11% 6% 3 5% 6% 3 5% 5% 6% 8% 41%	2155
	21st to end	Day	8% 6% 3 6% 8% 5% 7% 7% 8% 10% 32%	2531
June	1st to 10th	Day	9% 5% 3 6% 7% 4 6% 6% 8% 9% 37%	2340
	11th to 20th	Day	5% 5% 3 6% 6% 5% 8% 8% 8% 11% 36%	2340
	21st to end	Day	9% 6% 3 6% 9% 4 7% 9% 8% 10% 29%	2340
July	1st to 10th	Day	10% 5% 3 7% 8% 5% 8% 8% 8% 11% 28%	2340
	11th to 20th	Day	8% 5% 3 6% 7% 5% 8% 8% 7% 12% 31%	2340
	21st to end	Day	8% 6% 3 7% 8% 4 8% 7% 8% 10% 32%	2546
August	1st to 10th	Day	5% 3 2 5% 7% 5% 7% 7% 8% 12% 38%	2282
	11th to 20th	Day	7% 4 3 5% 6% 4 7% 8% 8% 12% 36%	2125
	21st to end	Day	11% 5% 3 7% 8% 5% 7% 7% 7% 9% 32%	2376
September	1st to 10th	Day	9% 6% 2 6% 7% 4 5% 6% 7% 9% 39%	2160
	11th to 20th	Day	14% 6% 2 6% 6% 4 5% 5% 6% 7% 38%	2054
	21st to end	Day	11% 6% 2 4 4 3 5% 5% 5% 7% 48%	1922
October	1st to 10th	Day	7% 4 2 4 5% 2 4 4 5% 7% 56%	1800
	11th to 20th	Day	10% 4 2 4 5% 3 5% 5% 5% 6% 51%	1800
	21st to end	Day	14% 5% 2 4 3 2 3 4 4 5% 52%	1980
November	1st to 10th	Day	11% 6% 2 5% 5% 3 4 4 5% 6% 49%	1858
	11th to 20th	Day	13% 6% 2 5% 5% 3 3 3 4 5% 51%	1900
	21st to end	Day	18% 7% 2 5% 4 3 4 3 4 5% 44%	1900
December	1st to 10th	Day	17% 8% 3 4 4 2 3 4 6% 6% 42%	1806
	11th to 20th	Day	18% 9% 3 5% 6% 3 5% 4 4 6% 39%	2161
	21st to end	Day	18% 8% 3 5% 5% 2 4 4 4 6% 42%	3135
January	1st to 10th	Night	19% 7% 3 4 3 3 3 3 4 7% 45%	2458
	11th to 20th	Night	19% 7% 2 5% 4 2 4 3 4 5% 45%	2418
	21st to end	Night	19% 8% 3 5% 4 2 3 4 4 5% 44%	2574
February	1st to 10th	Night	18% 8% 3 5% 5% 2 4 3 4 6% 41%	2340
	11th to 20th	Night	23% 7% 2 4 4 2 3 4 3 5% 42%	2073
	21st to end	Night	25% 8% 4 6% 4 2 4 4 4 6% 35%	1628
March	1st to 10th	Night	20% 8% 3 4 4 3 4 3 4 7% 42%	1980
	11th to 20th	Night	16% 8% 3 6% 5% 3 4 4 5% 7% 39%	1980
	21st to end	Night	14% 6% 3 4 4 3 3 4 6% 7% 47%	2178
April	1st to 10th	Night	15% 5% 3 4 5% 3 5% 5% 4 8% 43%	1877
	11th to 20th	Night	16% 6% 2 4 4 2 4 4 5% 7% 46%	1775
	21st to end	Night	11% 4 2 5% 5% 3 4 5% 5% 7% 49%	1800
May	1st to 10th	Night	12% 6% 3 5% 6% 3 4 5% 6% 9% 42%	1800
	11th to 20th	Night	10% 5% 2 5% 5% 2 3 4 5% 9% 51%	1734
	21st to end	Night	8% 4 3 5% 4 3 4 5% 7% 10% 47%	1745
June	1st to 10th	Night	6% 4 2 4 5% 3 5% 5% 7% 8% 51%	1620
	11th to 20th	Night	4 3 2 4 3 3 4 5% 6% 12% 54%	1620
	21st to end	Night	6% 3 2 5% 6% 4 5% 6% 9% 11% 44%	1620
July	1st to 10th	Night	5% 5% 3 5% 5% 3 6% 6% 7% 11% 43%	1620
	11th to 20th	Night	5% 3 2 4 3 3 5% 7% 8% 12% 50%	1620
	21st to end	Night	5% 3 2 4 5% 3 6% 6% 8% 12% 45%	1772
August	1st to 10th	Night	3 2 1 4 3 3 4 6% 7% 13% 55%	1654
	11th to 20th	Night	4 3 2 3 4 3 6% 7% 10% 12% 45%	1776
	21st to end	Night	10% 4 2 5% 6% 4 6% 7% 8% 11% 39%	1980
September	1st to 10th	Night	8% 4 2 5% 5% 3 5% 6% 6% 10% 47%	1800
	11th to 20th	Night	11% 5% 2 4 6% 3 4 5% 7% 7% 44%	1899
	21st to end	Night	9% 5% 2 5% 4 3 4 3 5% 6% 55%	2018
October	1st to 10th	Night	6% 4 1 4 4 3 4 4 5% 7% 57%	2160
	11th to 20th	Night	10% 4 2 4 4 2 4 4 4 6% 55%	2160
	21st to end	Night	12% 5% 2 3 3 2 3 3 4 5% 58%	2376
November	1st to 10th	Night	10% 4 2 4 4 3 3 4 4 7% 56%	2220
	11th to 20th	Night	12% 5% 2 4 4 2 3 3 5% 8% 53%	2280
	21st to end	Night	16% 8% 3 5% 4 3 4 4 4 5% 44%	2280
December	1st to 10th	Night	20% 7% 2 5% 4 2 4 4 4 6% 43%	2369
	11th to 20th	Night	16% 9% 3 5% 5% 2 3 4 4 5% 44%	3036
	21st to end	Night	18% 10% 2 4 4 2 3 4 5% 6% 42%	4532

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% 4 6% 19% 19% 10%	1708
	11th to 20th	Day	43% 3 5% 17% 22% 10%	1670
	21st to end	Day	47% 3 6% 14% 19% 12%	1782
February	1st to 10th	Day	49% 4 6% 14% 18% 9%	1620
	11th to 20th	Day	50% 5% 5% 14% 17% 10%	1794
	21st to end	Day	52% 5% 6% 11% 16% 10%	1628
March	1st to 10th	Day	52% 3 7% 14% 16% 9%	1980
	11th to 20th	Day	48% 5% 8% 12% 21% 7%	1980
	21st to end	Day	43% 5% 7% 16% 23% 6%	2178
April	1st to 10th	Day	44% 6% 8% 16% 18% 7%	2081
	11th to 20th	Day	45% 5% 9% 16% 15% 9%	2134
	21st to end	Day	40% 6% 9% 18% 22% 5%	2160
May	1st to 10th	Day	42% 6% 10% 18% 17% 6%	2160
	11th to 20th	Day	39% 7% 11% 24% 15% 3	2159
	21st to end	Day	44% 9% 14% 19% 12% 1	2531
June	1st to 10th	Day	41% 9% 15% 20% 14% 1	2340
	11th to 20th	Day	39% 10% 14% 24% 13% 1	2340
	21st to end	Day	44% 13% 16% 17% 10%	2340
July	1st to 10th	Day	47% 12% 17% 18% 5% 1	2276
	11th to 20th	Day	42% 11% 19% 20% 7%	2271
	21st to end	Day	42% 12% 19% 21% 6% 1	2405
August	1st to 10th	Day	34% 13% 19% 24% 9%	2268
	11th to 20th	Day	36% 12% 20% 23% 8% 1	2125
	21st to end	Day	45% 12% 15% 17% 9% 2	2376
September	1st to 10th	Day	39% 10% 13% 18% 14% 5%	2160
	11th to 20th	Day	45% 7% 12% 14% 16% 6%	2054
	21st to end	Day	35% 7% 11% 21% 18% 9%	1922
October	1st to 10th	Day	30% 5% 8% 19% 25% 13%	1800
	11th to 20th	Day	33% 5% 5% 17% 26% 14%	1800
	21st to end	Day	33% 5% 4 15% 27% 16%	1980
November	1st to 10th	Day	37% 5% 6% 18% 23% 11%	1858
	11th to 20th	Day	37% 4 6% 15% 28% 12%	1900
	21st to end	Day	44% 4 6% 17% 21% 8%	1900
December	1st to 10th	Day	43% 4 9% 20% 16% 8%	1806
	11th to 20th	Day	48% 4 5% 13% 21% 9%	2159
	21st to end	Day	45% 4 5% 15% 25% 7%	3135
January	1st to 10th	Night	42% 3 5% 17% 24% 9%	2458
	11th to 20th	Night	42% 3 5% 17% 22% 10%	2418
	21st to end	Night	45% 4 5% 14% 20% 13%	2574
February	1st to 10th	Night	46% 3 5% 15% 18% 12%	2340
	11th to 20th	Night	46% 4 5% 15% 20% 10%	2074
	21st to end	Night	53% 4 6% 10% 14% 13%	1628
March	1st to 10th	Night	45% 4 8% 14% 18% 11%	1980
	11th to 20th	Night	45% 5% 9% 12% 20% 8%	1980
	21st to end	Night	37% 5% 10% 18% 22% 7%	2178
April	1st to 10th	Night	40% 6% 10% 18% 17% 9%	1877
	11th to 20th	Night	38% 5% 12% 18% 15% 12%	1775
	21st to end	Night	35% 6% 10% 19% 23% 7%	1800
May	1st to 10th	Night	39% 6% 13% 18% 17% 8%	1800
	11th to 20th	Night	33% 5% 12% 25% 23% 3	1735
	21st to end	Night	31% 9% 17% 26% 15% 1	1746
June	1st to 10th	Night	28% 9% 20% 26% 16% 1	1620
	11th to 20th	Night	23% 8% 19% 34% 14% 2	1620
	21st to end	Night	31% 11% 22% 25% 10% 1	1620
July	1st to 10th	Night	32% 12% 26% 22% 7% 1	1575
	11th to 20th	Night	25% 13% 32% 24% 6%	1566
	21st to end	Night	26% 13% 28% 22% 10% 1	1673
August	1st to 10th	Night	20% 9% 31% 31% 10%	1644
	11th to 20th	Night	26% 14% 26% 24% 9% 1	1776
	21st to end	Night	36% 13% 20% 19% 9% 2	1980
September	1st to 10th	Night	30% 10% 18% 24% 13% 6%	1800
	11th to 20th	Night	37% 9% 14% 18% 15% 7%	1899
	21st to end	Night	29% 5% 13% 21% 19% 12%	2018
October	1st to 10th	Night	26% 7% 11% 22% 20% 14%	2160
	11th to 20th	Night	31% 5% 5% 19% 25% 16%	2160
	21st to end	Night	30% 4 6% 16% 25% 19%	2376
November	1st to 10th	Night	30% 5% 10% 19% 25% 12%	2220
	11th to 20th	Night	32% 4 9% 17% 25% 13%	2280
	21st to end	Night	42% 4 7% 17% 21% 10%	2280
December	1st to 10th	Night	44% 4 8% 19% 18% 8%	2369
	11th to 20th	Night	44% 3 5% 13% 22% 13%	3037
	21st to end	Night	44% 5% 6% 16% 23% 7%	4532

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% 17% 33% 17% 6% 1	257
	21st to end	Day	28% 25% 31% 13% 3	264
February	1st to 10th	Day	28% 17% 33% 17% 4 1	240
	11th to 20th	Day	37% 18% 30% 13% 2	240
	21st to end	Day	32% 23% 35% 11%	198
March	1st to 10th	Day	29% 18% 34% 14% 5%	240
	11th to 20th	Day	21% 25% 35% 14% 5%	240
	21st to end	Day	21% 21% 39% 13% 5%	264
April	1st to 10th	Day	19% 17% 36% 23% 5%	341
	11th to 20th	Day	28% 13% 25% 20% 12% 1	412
	21st to end	Day	15% 13% 35% 24% 13% 1	420
May	1st to 10th	Day	18% 10% 32% 25% 14% 1	423
	11th to 20th	Day	12% 6% 25% 33% 19% 5%	478
	21st to end	Day	9% 5% 26% 33% 20% 8%	679
June	1st to 10th	Day	8% 3 17% 33% 28% 12%	630
	11th to 20th	Day	6% 3 17% 34% 30% 10%	630
	21st to end	Day	10% 3 13% 27% 31% 16%	630
July	1st to 10th	Day	7% 2 10% 27% 36% 18%	621
	11th to 20th	Day	5% 1 7% 26% 41% 20%	618
	21st to end	Day	8% 1 7% 26% 41% 17%	684
August	1st to 10th	Day	5% 1 7% 20% 45% 23%	580
	11th to 20th	Day	6% 3 18% 45% 27%	439
	21st to end	Day	12% 2 8% 20% 31% 27%	495
September	1st to 10th	Day	8% 1 6% 27% 37% 21%	450
	11th to 20th	Day	14% 1 10% 30% 30% 15%	344
	21st to end	Day	16% 2 11% 31% 30% 10%	270
October	1st to 10th	Day	8% 5% 20% 38% 21% 7%	270
	11th to 20th	Day	10% 5% 28% 32% 18% 7%	270
	21st to end	Day	22% 11% 21% 30% 11% 4	297
November	1st to 10th	Day	15% 9% 23% 35% 14% 4	270
	11th to 20th	Day	17% 13% 34% 27% 9%	270
	21st to end	Day	23% 16% 34% 19% 7% 1	270
December	1st to 10th	Day	21% 15% 33% 19% 10% 2	270
	11th to 20th	Day	23% 13% 40% 20% 4 1	270
	21st to end	Day	28% 17% 35% 13% 5% 1	297
January	1st to 10th	Night	24% 13% 32% 25% 6%	950
	11th to 20th	Night	24% 12% 30% 25% 8%	930
	21st to end	Night	25% 12% 31% 28% 5%	990
February	1st to 10th	Night	24% 14% 34% 24% 5%	900
	11th to 20th	Night	30% 13% 30% 22% 5%	678
	21st to end	Night	29% 13% 32% 23% 2	444
March	1st to 10th	Night	24% 13% 29% 29% 5%	540
	11th to 20th	Night	20% 12% 35% 26% 6% 1	540
	21st to end	Night	17% 11% 35% 28% 8%	594
April	1st to 10th	Night	15% 12% 39% 27% 7%	540
	11th to 20th	Night	18% 12% 31% 28% 11% 1	533
	21st to end	Night	13% 10% 34% 30% 12% 1	540
May	1st to 10th	Night	13% 8% 33% 33% 12%	540
	11th to 20th	Night	12% 4 31% 34% 18% 2	531
	21st to end	Night	8% 4 19% 39% 27% 4	584
June	1st to 10th	Night	7% 2 9% 39% 38% 6%	540
	11th to 20th	Night	5% 3 12% 46% 30% 4	540
	21st to end	Night	7% 1 9% 31% 43% 9%	540
July	1st to 10th	Night	5% 2 6% 35% 41% 12%	525
	11th to 20th	Night	5% 1 6% 32% 43% 13%	522
	21st to end	Night	5% 1 5% 31% 47% 10%	591
August	1st to 10th	Night	4 6% 32% 47% 11%	537
	11th to 20th	Night	5% 1 4 28% 51% 12%	534
	21st to end	Night	10% 1 7% 22% 46% 14%	594
September	1st to 10th	Night	11% 1 5% 29% 45% 9%	540
	11th to 20th	Night	13% 1 9% 24% 45% 8%	540
	21st to end	Night	12% 2 11% 29% 41% 6%	578
October	1st to 10th	Night	8% 2 15% 33% 39% 4	720
	11th to 20th	Night	13% 4 23% 36% 22% 2	720
	21st to end	Night	14% 9% 21% 34% 20% 2	792
November	1st to 10th	Night	11% 6% 23% 36% 22% 3	740
	11th to 20th	Night	14% 9% 25% 36% 16% 1	760
	21st to end	Night	19% 9% 30% 28% 13% 1	760
December	1st to 10th	Night	23% 11% 25% 30% 11%	849
	11th to 20th	Night	25% 11% 30% 27% 7%	950
	21st to end	Night	27% 11% 27% 29% 6%	1045

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