Dogwood Ridge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dogwood Ridge Observatory clear sky chart from 2005-11-06 to 2024-11-25.

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	14% 6% 2 6% 4 4 4 4 6% 8% 42%	101149
	Night	15% 6% 2 6% 4 4 4 4 5% 7% 43%	98243
Transparency	Day	39% 4 12% 24% 18% 4	104799
	Night	40% 4 10% 23% 19% 5%	102732
Seeing	Day	19% 10% 25% 26% 15% 6%	15131
	Night	17% 8% 26% 33% 14% 2	24900

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% 5% 2 4 3 3 3 3 4 5% 49%	2836
	11th to 20th	Day	15% 8% 2 6% 4 4 4 3 4 5% 44%	2840
	21st to end	Day	19% 9% 3 6% 4 4 4 4 4 6% 39%	3124
February	1st to 10th	Day	13% 8% 3 6% 4 4 5% 5% 6% 6% 42%	1710
	11th to 20th	Day	19% 6% 2 6% 4 3 2 3 6% 5% 43%	1667
	21st to end	Day	18% 8% 2 7% 5% 4 5% 3 4 6% 37%	1636
March	1st to 10th	Day	20% 7% 2 6% 4 4 4 3 5% 7% 38%	3435
	11th to 20th	Day	11% 5% 2 5% 3 3 4 3 5% 7% 51%	3480
	21st to end	Day	20% 6% 3 6% 5% 4 4 4 5% 6% 37%	3815
April	1st to 10th	Day	11% 5% 2 5% 4 4 4 4 5% 6% 50%	2249
	11th to 20th	Day	12% 6% 2 5% 4 3 4 4 5% 6% 49%	2254
	21st to end	Day	17% 5% 2 5% 5% 5% 4 4 5% 6% 42%	2287
May	1st to 10th	Day	16% 7% 3 8% 5% 5% 6% 4 6% 7% 33%	4082
	11th to 20th	Day	21% 6% 2 6% 4 4 5% 4 6% 9% 32%	4081
	21st to end	Day	9% 4 2 5% 4 4 5% 4 7% 10% 46%	4693
June	1st to 10th	Day	10% 4 2 5% 5% 4 5% 4 7% 10% 44%	2660
	11th to 20th	Day	10% 4 1 6% 4 5% 5% 5% 9% 10% 40%	2660
	21st to end	Day	7% 4 2 5% 4 5% 6% 5% 8% 11% 43%	2660
July	1st to 10th	Day	6% 4 2 5% 4 5% 6% 5% 9% 11% 43%	4219
	11th to 20th	Day	10% 5% 2 6% 5% 5% 5% 5% 8% 13% 37%	4120
	21st to end	Day	11% 7% 3 7% 7% 6% 6% 5% 7% 9% 32%	4466
August	1st to 10th	Day	15% 6% 2 7% 5% 5% 6% 5% 8% 10% 32%	4104
	11th to 20th	Day	9% 5% 2 6% 5% 5% 5% 5% 8% 10% 40%	3933
	21st to end	Day	8% 4 1 5% 4 4 4 4 5% 11% 50%	4180
September	1st to 10th	Day	12% 5% 3 6% 4 4 4 4 5% 7% 47%	2280
	11th to 20th	Day	13% 6% 2 6% 4 4 4 3 6% 8% 45%	2213
	21st to end	Day	22% 6% 3 5% 4 4 4 4 6% 6% 37%	2019
October	1st to 10th	Day	15% 5% 2 5% 4 3 4 3 4 5% 50%	1900
	11th to 20th	Day	15% 4 1 4 4 3 4 3 5% 5% 52%	1900
	21st to end	Day	13% 5% 2 5% 2 3 2 2 5% 4 55%	2090
November	1st to 10th	Day	13% 4 2 4 4 3 3 3 4 6% 55%	1957
	11th to 20th	Day	15% 6% 2 5% 3 3 3 4 5% 6% 50%	1799
	21st to end	Day	15% 5% 1 5% 3 3 4 3 5% 6% 51%	1552
December	1st to 10th	Day	17% 7% 2 4 4 4 4 4 6% 7% 41%	1520
	11th to 20th	Day	17% 5% 2 4 3 3 3 3 4 5% 51%	1910
	21st to end	Day	19% 7% 3 6% 5% 3 3 3 5% 7% 39%	2818
January	1st to 10th	Night	14% 7% 2 5% 3 4 4 3 5% 5% 48%	4109
	11th to 20th	Night	18% 8% 3 4 3 3 3 3 3 4 48%	4120
	21st to end	Night	20% 8% 2 6% 4 4 3 2 3 5% 43%	4532
February	1st to 10th	Night	14% 7% 2 5% 4 4 4 4 6% 7% 43%	2470
	11th to 20th	Night	20% 8% 2 4 4 4 4 2 4 5% 44%	2398
	21st to end	Night	16% 7% 2 5% 3 3 4 3 5% 6% 45%	1813
March	1st to 10th	Night	20% 7% 2 7% 4 4 4 3 5% 6% 38%	3418
	11th to 20th	Night	12% 4 1 5% 3 3 4 3 6% 8% 51%	3480
	21st to end	Night	15% 6% 2 5% 3 3 4 3 4 6% 48%	3817
April	1st to 10th	Night	14% 6% 2 5% 5% 3 4 3 5% 7% 46%	1930
	11th to 20th	Night	11% 5% 2 5% 4 3 3 3 5% 9% 49%	1875
	21st to end	Night	15% 6% 2 4 4 4 4 4 5% 7% 45%	1900
May	1st to 10th	Night	18% 9% 3 7% 4 4 4 3 5% 8% 35%	2822
	11th to 20th	Night	23% 7% 2 6% 4 4 4 4 5% 8% 33%	2812
	21st to end	Night	10% 4 2 6% 5% 4 5% 5% 6% 9% 44%	2858
June	1st to 10th	Night	11% 5% 1 5% 4 4 5% 5% 8% 9% 43%	1520
	11th to 20th	Night	9% 6% 2 6% 5% 5% 5% 4 7% 9% 42%	1520
	21st to end	Night	8% 4 2 5% 5% 5% 4 5% 7% 10% 45%	1520
July	1st to 10th	Night	7% 5% 2 7% 5% 6% 7% 6% 7% 10% 38%	2734
	11th to 20th	Night	8% 6% 3 7% 6% 7% 6% 6% 8% 10% 34%	2840
	21st to end	Night	10% 8% 4 10% 7% 6% 6% 5% 7% 9% 29%	3087
August	1st to 10th	Night	16% 6% 3 7% 6% 4 5% 4 8% 9% 32%	2825
	11th to 20th	Night	10% 5% 3 8% 5% 5% 6% 6% 7% 9% 35%	2849
	21st to end	Night	10% 6% 2 6% 4 5% 5% 4 6% 8% 43%	3476
September	1st to 10th	Night	13% 5% 2 5% 4 5% 4 3 6% 7% 45%	1900
	11th to 20th	Night	13% 5% 2 5% 4 4 5% 4 5% 8% 44%	1964
	21st to end	Night	23% 8% 3 5% 3 3 3 4 5% 5% 38%	2161
October	1st to 10th	Night	17% 5% 2 6% 2 4 3 3 4 6% 46%	2280
	11th to 20th	Night	15% 4 2 5% 3 3 3 3 5% 6% 49%	2280
	21st to end	Night	13% 4 1 4 3 3 4 3 5% 6% 54%	2508
November	1st to 10th	Night	13% 6% 2 6% 4 3 3 2 3 5% 53%	2341
	11th to 20th	Night	14% 5% 2 5% 4 4 3 3 4 6% 49%	2596
	21st to end	Night	13% 4 2 5% 3 4 4 4 5% 6% 51%	2723
December	1st to 10th	Night	16% 8% 3 6% 4 4 4 3 5% 5% 43%	2660
	11th to 20th	Night	17% 6% 2 5% 3 3 3 3 5% 6% 47%	3285
	21st to end	Night	17% 6% 2 5% 4 5% 5% 3 6% 6% 41%	4820

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	39% 2 6% 31% 17% 6%	2837
	11th to 20th	Day	44% 2 7% 19% 22% 7%	2840
	21st to end	Day	48% 2 7% 24% 16% 3	3124
February	1st to 10th	Day	42% 3 10% 26% 15% 3	1710
	11th to 20th	Day	42% 3 6% 22% 21% 5%	1676
	21st to end	Day	48% 4 11% 15% 17% 6%	1636
March	1st to 10th	Day	48% 2 9% 21% 13% 7%	3435
	11th to 20th	Day	33% 3 7% 24% 24% 9%	3480
	21st to end	Day	49% 3 9% 19% 17% 3	3815
April	1st to 10th	Day	35% 3 11% 23% 20% 9%	2249
	11th to 20th	Day	36% 3 10% 22% 22% 6%	2254
	21st to end	Day	43% 3 10% 24% 16% 5%	2287
May	1st to 10th	Day	49% 4 13% 19% 13% 1	4120
	11th to 20th	Day	49% 5% 11% 22% 12% 1	4085
	21st to end	Day	33% 5% 16% 23% 21% 2	4707
June	1st to 10th	Day	34% 6% 16% 26% 16% 1	2660
	11th to 20th	Day	36% 7% 16% 24% 16% 2	2660
	21st to end	Day	32% 7% 16% 27% 15% 2	2660
July	1st to 10th	Day	32% 9% 23% 19% 11% 6%	4154
	11th to 20th	Day	37% 6% 19% 27% 9% 1	4051
	21st to end	Day	46% 7% 12% 21% 13% 1	4324
August	1st to 10th	Day	45% 6% 17% 25% 7% 1	4091
	11th to 20th	Day	36% 6% 16% 26% 14% 1	3972
	21st to end	Day	30% 5% 18% 29% 17% 1	4180
September	1st to 10th	Day	38% 4 13% 18% 22% 4	2280
	11th to 20th	Day	37% 5% 7% 27% 20% 4	2213
	21st to end	Day	47% 4 8% 20% 18% 3	2019
October	1st to 10th	Day	35% 3 6% 19% 31% 5%	3160
	11th to 20th	Day	26% 3 6% 23% 32% 12%	3140
	21st to end	Day	21% 2 9% 30% 25% 12%	3428
November	1st to 10th	Day	33% 3 7% 24% 28% 5%	1957
	11th to 20th	Day	36% 3 9% 22% 22% 8%	1799
	21st to end	Day	34% 3 8% 25% 24% 5%	1552
December	1st to 10th	Day	42% 3 11% 24% 15% 5%	1520
	11th to 20th	Day	37% 2 7% 29% 17% 8%	1906
	21st to end	Day	46% 2 9% 27% 14% 1	2818
January	1st to 10th	Night	39% 3 6% 24% 23% 5%	4109
	11th to 20th	Night	42% 3 5% 21% 24% 6%	4120
	21st to end	Night	46% 2 6% 24% 17% 5%	4532
February	1st to 10th	Night	40% 4 10% 26% 18% 3	2470
	11th to 20th	Night	44% 2 6% 20% 20% 7%	2400
	21st to end	Night	42% 2 9% 23% 18% 7%	1813
March	1st to 10th	Night	48% 3 7% 23% 16% 3	3418
	11th to 20th	Night	32% 3 6% 22% 28% 9%	3480
	21st to end	Night	39% 3 9% 23% 21% 5%	3817
April	1st to 10th	Night	39% 5% 9% 18% 23% 7%	1930
	11th to 20th	Night	34% 3 13% 21% 23% 6%	1875
	21st to end	Night	37% 4 11% 24% 17% 6%	1900
May	1st to 10th	Night	49% 3 14% 20% 12% 2	2849
	11th to 20th	Night	49% 5% 10% 24% 10% 1	2813
	21st to end	Night	37% 5% 16% 25% 15% 2	2865
June	1st to 10th	Night	35% 6% 13% 28% 17% 1	1520
	11th to 20th	Night	37% 7% 17% 22% 15% 2	1520
	21st to end	Night	34% 6% 15% 24% 18% 3	1520
July	1st to 10th	Night	39% 9% 23% 15% 12% 3	2689
	11th to 20th	Night	42% 9% 19% 22% 8% 1	2786
	21st to end	Night	49% 7% 13% 19% 10%	2988
August	1st to 10th	Night	47% 6% 17% 23% 6% 1	2814
	11th to 20th	Night	42% 7% 14% 24% 12% 1	2876
	21st to end	Night	38% 4 14% 30% 11% 2	3476
September	1st to 10th	Night	38% 5% 12% 21% 16% 7%	1900
	11th to 20th	Night	38% 5% 10% 24% 20% 3	1964
	21st to end	Night	47% 5% 8% 21% 16% 4	2161
October	1st to 10th	Night	42% 4 8% 19% 21% 6%	3800
	11th to 20th	Night	26% 3 7% 21% 31% 11%	3779
	21st to end	Night	21% 2 6% 32% 28% 11%	4120
November	1st to 10th	Night	35% 3 7% 22% 26% 6%	2341
	11th to 20th	Night	38% 2 7% 21% 24% 8%	2596
	21st to end	Night	35% 3 9% 25% 23% 6%	2723
December	1st to 10th	Night	44% 3 8% 24% 17% 4	2660
	11th to 20th	Night	40% 3 9% 21% 21% 7%	3288
	21st to end	Night	44% 2 10% 25% 17% 2	4820

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	25% 20% 30% 20% 4	270
	11th to 20th	Day	30% 24% 31% 12% 2	270
	21st to end	Day	27% 20% 37% 12% 4	297
February	1st to 10th	Day	25% 20% 39% 13% 4	270
	11th to 20th	Day	38% 22% 28% 11% 1	274
	21st to end	Day	30% 15% 30% 22% 3	382
March	1st to 10th	Day	24% 17% 31% 22% 6%	460
	11th to 20th	Day	22% 19% 35% 17% 6% 1	460
	21st to end	Day	23% 15% 36% 20% 6% 1	506
April	1st to 10th	Day	22% 17% 32% 19% 8% 1	460
	11th to 20th	Day	19% 15% 31% 19% 10% 5%	452
	21st to end	Day	25% 11% 31% 22% 9% 2	460
May	1st to 10th	Day	21% 14% 29% 23% 10% 3	463
	11th to 20th	Day	21% 8% 28% 27% 12% 4	487
	21st to end	Day	17% 5% 23% 30% 20% 5%	529
June	1st to 10th	Day	12% 7% 25% 28% 23% 5%	490
	11th to 20th	Day	12% 6% 23% 31% 18% 10%	490
	21st to end	Day	10% 4 23% 35% 21% 7%	490
July	1st to 10th	Day	11% 2 17% 31% 28% 11%	485
	11th to 20th	Day	7% 2 13% 36% 31% 11%	484
	21st to end	Day	11% 4 18% 31% 22% 13%	532
August	1st to 10th	Day	14% 3 16% 27% 27% 12%	486
	11th to 20th	Day	12% 4 17% 28% 26% 14%	479
	21st to end	Day	10% 2 16% 30% 26% 15%	539
September	1st to 10th	Day	14% 4 15% 29% 21% 17%	490
	11th to 20th	Day	16% 3 13% 34% 22% 11%	490
	21st to end	Day	30% 5% 20% 27% 14% 4	490
October	1st to 10th	Day	20% 4 22% 29% 18% 7%	490
	11th to 20th	Day	15% 10% 24% 27% 20% 3	490
	21st to end	Day	16% 10% 32% 27% 12% 3	539
November	1st to 10th	Day	16% 10% 26% 32% 13% 4	495
	11th to 20th	Day	18% 13% 32% 24% 11% 2	371
	21st to end	Day	19% 18% 29% 26% 7% 2	188
December	1st to 10th	Day	23% 13% 39% 17% 7% 2	180
	11th to 20th	Day	26% 13% 31% 21% 7% 2	180
	21st to end	Day	28% 15% 30% 17% 9% 1	213
January	1st to 10th	Night	19% 13% 38% 26% 3	760
	11th to 20th	Night	21% 14% 35% 27% 3	760
	21st to end	Night	18% 13% 40% 26% 3	836
February	1st to 10th	Night	18% 12% 36% 31% 3	760
	11th to 20th	Night	25% 13% 39% 21% 1	743
	21st to end	Night	23% 14% 36% 24% 3	628
March	1st to 10th	Night	18% 15% 36% 26% 5%	760
	11th to 20th	Night	21% 16% 34% 24% 5% 1	760
	21st to end	Night	19% 12% 35% 27% 6%	836
April	1st to 10th	Night	17% 14% 38% 25% 6%	760
	11th to 20th	Night	14% 12% 34% 30% 9%	751
	21st to end	Night	17% 8% 31% 35% 9%	760
May	1st to 10th	Night	19% 9% 30% 30% 13%	579
	11th to 20th	Night	20% 4 21% 37% 17% 1	561
	21st to end	Night	16% 1 17% 39% 23% 3	486
June	1st to 10th	Night	10% 2 18% 45% 24% 1	380
	11th to 20th	Night	11% 4 16% 40% 27% 1	380
	21st to end	Night	9% 2 17% 51% 19% 2	380
July	1st to 10th	Night	11% 2 12% 38% 32% 5%	488
	11th to 20th	Night	7% 1 11% 41% 35% 6%	552
	21st to end	Night	9% 2 14% 43% 28% 5%	624
August	1st to 10th	Night	15% 2 8% 40% 32% 4	567
	11th to 20th	Night	14% 2 9% 38% 33% 3	602
	21st to end	Night	11% 2 12% 37% 33% 5%	836
September	1st to 10th	Night	16% 2 10% 34% 32% 6%	760
	11th to 20th	Night	14% 3 14% 34% 31% 4	760
	21st to end	Night	27% 3 16% 31% 21% 2	760
October	1st to 10th	Night	20% 4 18% 32% 23% 4	760
	11th to 20th	Night	17% 7% 24% 34% 16% 1	760
	21st to end	Night	15% 6% 29% 35% 14% 1	836
November	1st to 10th	Night	16% 7% 26% 37% 13% 1	780
	11th to 20th	Night	18% 9% 31% 32% 10%	800
	21st to end	Night	14% 9% 33% 33% 10%	779
December	1st to 10th	Night	21% 10% 33% 28% 8%	760
	11th to 20th	Night	18% 9% 31% 36% 6%	760
	21st to end	Night	20% 10% 30% 36% 3	836

Page generated at 2024-11-22 08:02:30. Version ac07

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