Deep Creek Lake State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Deep Creek Lake State Park clear sky chart from 2005-11-06 to 2025-07-06.

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% 9% 4 9% 6% 5% 5% 4 6% 7% 30%	119842
	Night	12% 10% 4 10% 6% 5% 5% 4 5% 6% 32%	118919
Transparency	Day	48% 9% 11% 20% 11% 2	123489
	Night	48% 9% 11% 20% 11% 2	123409
Seeing	Day	26% 19% 27% 17% 8% 3	15662
	Night	24% 19% 24% 22% 10% 1	25382

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	12% 9% 11% 15% 12% 5% 4 4 5% 5% 19%	4056
	11th to 20th	Day	9% 13% 7% 22% 7% 9% 5% 3 4 5% 16%	4060
	21st to end	Day	12% 12% 6% 15% 8% 5% 4 4 5% 6% 23%	4466
February	1st to 10th	Day	12% 14% 6% 11% 8% 5% 4 5% 6% 6% 24%	1800
	11th to 20th	Day	15% 10% 4 14% 7% 5% 6% 4 6% 7% 23%	1753
	21st to end	Day	12% 13% 6% 13% 7% 6% 5% 4 4 4 27%	1677
March	1st to 10th	Day	13% 9% 7% 8% 5% 5% 5% 3 5% 6% 33%	4935
	11th to 20th	Day	10% 8% 4 8% 4 4 5% 4 6% 8% 38%	4980
	21st to end	Day	12% 10% 4 9% 6% 5% 5% 4 6% 6% 33%	5465
April	1st to 10th	Day	13% 12% 5% 9% 5% 5% 5% 4 5% 8% 29%	2334
	11th to 20th	Day	14% 11% 4 7% 5% 5% 4 4 5% 6% 36%	2374
	21st to end	Day	17% 10% 3 7% 6% 4 4 3 6% 7% 32%	2545
May	1st to 10th	Day	17% 10% 3 8% 6% 6% 6% 5% 7% 8% 25%	5862
	11th to 20th	Day	21% 8% 3 7% 5% 4 6% 5% 8% 9% 25%	5861
	21st to end	Day	16% 8% 3 8% 6% 5% 6% 5% 7% 8% 28%	6816
June	1st to 10th	Day	12% 7% 3 7% 5% 6% 5% 5% 8% 8% 34%	2800
	11th to 20th	Day	13% 7% 3 8% 6% 5% 7% 5% 7% 9% 31%	2800
	21st to end	Day	10% 7% 2 6% 5% 6% 6% 5% 7% 10% 35%	2800
July	1st to 10th	Day	8% 6% 3 8% 5% 6% 5% 4 6% 9% 40%	4363
	11th to 20th	Day	9% 7% 2 8% 5% 6% 6% 5% 7% 9% 36%	4120
	21st to end	Day	13% 9% 4 9% 6% 5% 5% 4 6% 7% 31%	4466
August	1st to 10th	Day	13% 7% 3 8% 6% 7% 7% 5% 7% 8% 29%	4104
	11th to 20th	Day	10% 7% 3 8% 6% 6% 6% 5% 7% 9% 33%	4044
	21st to end	Day	8% 5% 2 6% 5% 5% 6% 5% 7% 9% 42%	4221
September	1st to 10th	Day	14% 6% 3 7% 6% 5% 4 3 5% 6% 42%	2280
	11th to 20th	Day	12% 7% 3 7% 5% 4 4 4 6% 7% 41%	2146
	21st to end	Day	18% 11% 3 8% 5% 4 4 4 5% 7% 33%	2057
October	1st to 10th	Day	13% 9% 2 6% 5% 5% 4 3 5% 7% 40%	1900
	11th to 20th	Day	14% 13% 3 7% 4 4 4 3 5% 4 37%	1900
	21st to end	Day	14% 12% 2 8% 5% 5% 4 3 4 6% 37%	2090
November	1st to 10th	Day	10% 9% 4 6% 4 4 5% 3 4 6% 45%	1957
	11th to 20th	Day	11% 12% 4 10% 6% 4 5% 4 7% 6% 31%	1660
	21st to end	Day	13% 14% 6% 10% 6% 5% 4 3 5% 6% 27%	1600
December	1st to 10th	Day	11% 9% 5% 18% 9% 5% 5% 4 6% 6% 22%	2600
	11th to 20th	Day	17% 13% 6% 12% 6% 6% 5% 3 4 5% 24%	2990
	21st to end	Day	14% 12% 8% 13% 6% 6% 5% 4 7% 6% 19%	3960
January	1st to 10th	Night	8% 11% 7% 20% 14% 5% 5% 3 5% 5% 17%	5889
	11th to 20th	Night	9% 10% 6% 19% 11% 6% 5% 3 4 5% 21%	5900
	21st to end	Night	13% 10% 5% 13% 8% 6% 4 3 4 5% 29%	6490
February	1st to 10th	Night	11% 9% 4 11% 7% 6% 5% 4 7% 6% 29%	2600
	11th to 20th	Night	13% 10% 5% 14% 8% 6% 6% 4 5% 6% 24%	2533
	21st to end	Night	12% 12% 5% 11% 7% 5% 5% 4 5% 6% 27%	1946
March	1st to 10th	Night	14% 11% 5% 9% 6% 4 5% 4 5% 6% 33%	4918
	11th to 20th	Night	8% 9% 4 10% 4 4 4 3 5% 8% 41%	4980
	21st to end	Night	10% 10% 4 8% 5% 5% 5% 3 5% 6% 40%	5467
April	1st to 10th	Night	12% 12% 6% 9% 6% 5% 4 3 4 6% 32%	2065
	11th to 20th	Night	12% 10% 3 9% 5% 5% 5% 4 6% 7% 36%	1975
	21st to end	Night	14% 9% 3 8% 5% 5% 4 3 4 6% 38%	1870
May	1st to 10th	Night	22% 11% 4 8% 6% 5% 5% 3 5% 7% 25%	4033
	11th to 20th	Night	22% 11% 3 6% 4 4 5% 4 6% 7% 28%	4032
	21st to end	Night	16% 11% 3 8% 6% 5% 5% 4 6% 7% 29%	4021
June	1st to 10th	Night	9% 8% 3 5% 5% 5% 5% 5% 6% 7% 41%	1600
	11th to 20th	Night	11% 6% 3 8% 6% 5% 4 5% 7% 9% 36%	1600
	21st to end	Night	8% 6% 3 7% 5% 5% 5% 4 8% 12% 38%	1600
July	1st to 10th	Night	7% 7% 3 6% 5% 5% 6% 5% 7% 9% 39%	2702
	11th to 20th	Night	7% 7% 3 8% 6% 5% 5% 4 6% 8% 42%	2840
	21st to end	Night	11% 8% 3 7% 7% 4 5% 5% 6% 7% 37%	3087
August	1st to 10th	Night	15% 6% 2 6% 6% 5% 5% 4 7% 10% 33%	2825
	11th to 20th	Night	10% 9% 3 6% 6% 5% 4 4 5% 7% 40%	2785
	21st to end	Night	7% 6% 2 6% 5% 5% 4 4 6% 8% 48%	3402
September	1st to 10th	Night	12% 7% 2 6% 5% 4 4 4 5% 7% 45%	1900
	11th to 20th	Night	10% 7% 2 7% 4 3 3 3 5% 7% 48%	2030
	21st to end	Night	17% 9% 3 6% 4 4 4 3 5% 6% 37%	2122
October	1st to 10th	Night	14% 8% 2 6% 4 5% 5% 3 4 6% 43%	2280
	11th to 20th	Night	11% 10% 2 7% 4 4 5% 4 6% 7% 41%	2280
	21st to end	Night	15% 11% 3 6% 5% 5% 3 3 4 6% 39%	2508
November	1st to 10th	Night	9% 10% 3 7% 5% 4 4 3 4 6% 44%	2341
	11th to 20th	Night	12% 11% 5% 9% 7% 5% 5% 4 5% 6% 31%	2735
	21st to end	Night	12% 11% 5% 11% 6% 5% 6% 4 5% 6% 29%	2800
December	1st to 10th	Night	10% 10% 5% 18% 6% 5% 6% 4 7% 5% 24%	4580
	11th to 20th	Night	15% 10% 5% 15% 6% 6% 5% 3 5% 6% 24%	5205
	21st to end	Night	12% 13% 8% 16% 8% 6% 6% 5% 4 5% 18%	6978

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	62% 10% 8% 13% 7% 1	4057
	11th to 20th	Day	69% 7% 6% 10% 8% 1	4060
	21st to end	Day	56% 8% 11% 15% 9% 1	4466
February	1st to 10th	Day	56% 10% 10% 15% 9%	1800
	11th to 20th	Day	58% 9% 11% 13% 10%	1762
	21st to end	Day	56% 9% 8% 14% 10% 2	1677
March	1st to 10th	Day	49% 6% 9% 21% 11% 4	4935
	11th to 20th	Day	39% 9% 11% 27% 11% 3	4980
	21st to end	Day	48% 7% 9% 19% 15% 2	5465
April	1st to 10th	Day	51% 9% 11% 16% 11% 3	2334
	11th to 20th	Day	46% 8% 11% 16% 16% 3	2374
	21st to end	Day	50% 8% 11% 21% 10% 1	2545
May	1st to 10th	Day	54% 9% 10% 19% 7% 2	5897
	11th to 20th	Day	51% 10% 10% 23% 5% 1	5865
	21st to end	Day	47% 11% 12% 19% 9% 2	6831
June	1st to 10th	Day	43% 11% 11% 22% 12% 1	2800
	11th to 20th	Day	46% 11% 11% 22% 9% 1	2800
	21st to end	Day	41% 12% 13% 23% 11% 1	2800
July	1st to 10th	Day	39% 9% 12% 26% 11% 3	4297
	11th to 20th	Day	41% 9% 13% 26% 10% 1	4051
	21st to end	Day	48% 8% 8% 21% 13% 1	4324
August	1st to 10th	Day	48% 11% 14% 21% 7%	4091
	11th to 20th	Day	43% 8% 11% 28% 10%	4083
	21st to end	Day	34% 10% 14% 27% 14% 1	4221
September	1st to 10th	Day	42% 8% 10% 18% 18% 3	2280
	11th to 20th	Day	40% 7% 11% 25% 15% 2	2146
	21st to end	Day	49% 7% 11% 19% 14% 1	2057
October	1st to 10th	Day	33% 6% 8% 26% 22% 6%	3160
	11th to 20th	Day	38% 5% 12% 21% 14% 10%	3140
	21st to end	Day	31% 5% 10% 29% 22% 2	3428
November	1st to 10th	Day	39% 8% 9% 22% 17% 5%	1957
	11th to 20th	Day	49% 9% 9% 15% 15% 3	1660
	21st to end	Day	56% 8% 11% 15% 10% 1	1600
December	1st to 10th	Day	59% 7% 14% 16% 4 1	2600
	11th to 20th	Day	61% 7% 10% 15% 7% 1	2986
	21st to end	Day	60% 9% 12% 12% 7%	3960
January	1st to 10th	Night	64% 9% 7% 11% 8% 1	5889
	11th to 20th	Night	60% 8% 11% 10% 7% 3	5900
	21st to end	Night	52% 10% 11% 17% 9% 1	6490
February	1st to 10th	Night	51% 11% 10% 17% 10% 1	2600
	11th to 20th	Night	59% 8% 10% 13% 9%	2535
	21st to end	Night	54% 10% 8% 16% 9% 3	1946
March	1st to 10th	Night	48% 8% 10% 21% 10% 3	4918
	11th to 20th	Night	39% 9% 11% 29% 9% 4	4980
	21st to end	Night	42% 7% 13% 21% 15% 2	5467
April	1st to 10th	Night	52% 8% 9% 17% 12% 2	2065
	11th to 20th	Night	45% 9% 12% 18% 13% 3	1975
	21st to end	Night	45% 7% 10% 25% 10% 2	1870
May	1st to 10th	Night	56% 9% 11% 14% 8% 2	4060
	11th to 20th	Night	51% 10% 9% 23% 6%	4033
	21st to end	Night	47% 13% 12% 19% 6% 3	4028
June	1st to 10th	Night	39% 10% 11% 25% 14% 1	1600
	11th to 20th	Night	41% 10% 13% 24% 10% 1	1600
	21st to end	Night	36% 11% 15% 23% 14% 1	1600
July	1st to 10th	Night	38% 10% 14% 24% 11% 3	2658
	11th to 20th	Night	38% 9% 15% 27% 11% 1	2786
	21st to end	Night	43% 10% 11% 21% 15% 1	2988
August	1st to 10th	Night	43% 10% 18% 22% 7% 1	2814
	11th to 20th	Night	42% 7% 11% 25% 14%	2812
	21st to end	Night	33% 8% 14% 33% 11% 1	3402
September	1st to 10th	Night	37% 9% 12% 21% 17% 3	1900
	11th to 20th	Night	33% 8% 11% 27% 18% 2	2030
	21st to end	Night	45% 7% 12% 20% 16%	2122
October	1st to 10th	Night	36% 6% 9% 27% 20% 2	3800
	11th to 20th	Night	34% 7% 9% 22% 18% 9%	3779
	21st to end	Night	33% 6% 8% 28% 20% 5%	4120
November	1st to 10th	Night	40% 7% 10% 20% 17% 6%	2341
	11th to 20th	Night	51% 7% 8% 17% 13% 3	2735
	21st to end	Night	54% 8% 10% 16% 10% 2	2800
December	1st to 10th	Night	55% 8% 13% 18% 4 1	4580
	11th to 20th	Night	58% 8% 12% 15% 7%	5208
	21st to end	Night	64% 9% 9% 11% 7%	6978

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	44% 27% 20% 6% 3	300
	11th to 20th	Day	45% 28% 22% 4 1	300
	21st to end	Day	36% 35% 24% 4 2	330
February	1st to 10th	Day	39% 29% 25% 6% 1	300
	11th to 20th	Day	53% 24% 21% 3	300
	21st to end	Day	40% 31% 24% 4 1	336
March	1st to 10th	Day	35% 26% 26% 10% 2	500
	11th to 20th	Day	37% 27% 22% 11% 3 1	500
	21st to end	Day	35% 25% 26% 12% 2	550
April	1st to 10th	Day	32% 24% 28% 12% 4	500
	11th to 20th	Day	28% 22% 28% 13% 6% 2	492
	21st to end	Day	32% 24% 25% 13% 5% 1	500
May	1st to 10th	Day	31% 20% 29% 13% 4 2	503
	11th to 20th	Day	28% 21% 25% 17% 7% 3	527
	21st to end	Day	21% 17% 28% 19% 10% 5%	573
June	1st to 10th	Day	17% 18% 30% 20% 11% 4	530
	11th to 20th	Day	20% 16% 29% 20% 12% 4	530
	21st to end	Day	12% 17% 31% 25% 13% 2	530
July	1st to 10th	Day	12% 9% 31% 24% 16% 8%	505
	11th to 20th	Day	8% 11% 34% 27% 13% 6%	484
	21st to end	Day	16% 12% 27% 26% 13% 6%	532
August	1st to 10th	Day	12% 13% 28% 25% 16% 7%	486
	11th to 20th	Day	15% 10% 27% 25% 14% 10%	479
	21st to end	Day	12% 9% 27% 27% 15% 10%	539
September	1st to 10th	Day	16% 11% 24% 24% 16% 8%	490
	11th to 20th	Day	14% 8% 28% 24% 19% 7%	490
	21st to end	Day	28% 14% 25% 18% 11% 3	490
October	1st to 10th	Day	20% 13% 29% 23% 13% 3	490
	11th to 20th	Day	25% 21% 26% 20% 7% 1	490
	21st to end	Day	28% 23% 27% 15% 8%	539
November	1st to 10th	Day	23% 19% 29% 18% 8% 2	495
	11th to 20th	Day	28% 28% 30% 9% 5%	232
	21st to end	Day	36% 29% 26% 8% 2 1	200
December	1st to 10th	Day	39% 30% 23% 6% 2 2	200
	11th to 20th	Day	42% 25% 24% 8% 2	200
	21st to end	Day	36% 27% 22% 12% 3	220
January	1st to 10th	Night	34% 31% 23% 9% 3	800
	11th to 20th	Night	34% 29% 25% 12% 1	800
	21st to end	Night	35% 30% 24% 10% 1	880
February	1st to 10th	Night	32% 25% 27% 15% 1	800
	11th to 20th	Night	36% 33% 24% 7%	783
	21st to end	Night	33% 29% 27% 10% 1	660
March	1st to 10th	Night	29% 25% 27% 17% 2	800
	11th to 20th	Night	33% 23% 24% 15% 5% 1	800
	21st to end	Night	24% 26% 31% 15% 4 1	880
April	1st to 10th	Night	25% 26% 30% 17% 3	800
	11th to 20th	Night	23% 20% 29% 21% 7% 1	791
	21st to end	Night	24% 17% 26% 26% 6%	670
May	1st to 10th	Night	24% 15% 26% 27% 8%	600
	11th to 20th	Night	25% 12% 25% 26% 10% 1	591
	21st to end	Night	11% 12% 25% 28% 22% 2	483
June	1st to 10th	Night	12% 12% 24% 35% 15% 1	400
	11th to 20th	Night	14% 10% 24% 32% 19% 1	400
	21st to end	Night	11% 8% 31% 34% 15% 1	400
July	1st to 10th	Night	9% 8% 23% 35% 21% 4	453
	11th to 20th	Night	7% 8% 21% 36% 24% 4	552
	21st to end	Night	10% 8% 22% 35% 24% 2	624
August	1st to 10th	Night	11% 6% 18% 39% 24% 2	567
	11th to 20th	Night	11% 7% 17% 38% 23% 4	564
	21st to end	Night	11% 6% 19% 37% 23% 3	788
September	1st to 10th	Night	16% 6% 23% 32% 20% 4	760
	11th to 20th	Night	14% 8% 18% 34% 23% 3	760
	21st to end	Night	23% 13% 18% 28% 16% 2	760
October	1st to 10th	Night	19% 13% 23% 25% 18% 2	760
	11th to 20th	Night	21% 17% 27% 25% 9% 1	760
	21st to end	Night	26% 21% 24% 22% 6% 1	836
November	1st to 10th	Night	19% 18% 27% 26% 9% 1	780
	11th to 20th	Night	29% 21% 25% 18% 6% 1	800
	21st to end	Night	29% 23% 27% 17% 4 1	800
December	1st to 10th	Night	33% 26% 23% 13% 5%	800
	11th to 20th	Night	31% 28% 23% 16% 2	800
	21st to end	Night	29% 26% 26% 17% 2	880

Page generated at 2025-07-03 01:30:17. Version ac07

Copyright © 2025 Attilla Danko.