Deer Path Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Deer Path Park clear sky chart from 2005-11-06 to 2025-07-21.

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	17% 7% 2 6% 4 4 4 4 5% 7% 40%	120112
	Night	17% 7% 2 5% 4 4 4 3 5% 6% 42%	118962
Transparency	Day	42% 6% 11% 22% 16% 3	123671
	Night	41% 5% 11% 23% 17% 3	123564
Seeing	Day	23% 15% 29% 21% 10% 3	15847
	Night	21% 13% 31% 26% 9% 1	25057

By Month

Percentage Cloud Cover NE (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	13% 6% 3 6% 3 4 4 3 5% 6% 47%	3597
	11th to 20th	Day	13% 8% 3 9% 6% 4 4 3 5% 6% 39%	3570
	21st to end	Day	18% 8% 3 7% 5% 4 4 3 4 5% 40%	4448
February	1st to 10th	Day	17% 8% 2 8% 3 4 4 3 6% 6% 39%	1800
	11th to 20th	Day	16% 7% 3 8% 5% 4 4 3 5% 5% 40%	1914
	21st to end	Day	20% 9% 3 6% 4 4 5% 3 4 4 39%	1650
March	1st to 10th	Day	22% 6% 2 5% 4 3 4 3 5% 5% 43%	4476
	11th to 20th	Day	12% 6% 2 6% 5% 4 5% 4 6% 7% 43%	4906
	21st to end	Day	18% 5% 2 6% 3 3 4 3 5% 7% 43%	5832
April	1st to 10th	Day	18% 8% 3 6% 5% 4 4 3 5% 6% 38%	2400
	11th to 20th	Day	16% 7% 2 6% 4 4 5% 3 6% 8% 40%	2374
	21st to end	Day	16% 6% 3 6% 5% 4 4 4 5% 7% 40%	2400
May	1st to 10th	Day	27% 8% 2 6% 4 4 4 4 5% 8% 29%	5893
	11th to 20th	Day	24% 9% 2 6% 4 4 4 3 5% 6% 34%	6318
	21st to end	Day	20% 6% 2 6% 4 4 4 4 6% 8% 35%	6949
June	1st to 10th	Day	15% 6% 2 6% 4 5% 6% 5% 7% 8% 38%	2800
	11th to 20th	Day	15% 6% 3 7% 6% 5% 5% 5% 6% 8% 36%	2800
	21st to end	Day	13% 6% 2 6% 5% 4 5% 4 6% 8% 41%	2800
July	1st to 10th	Day	8% 6% 3 7% 6% 6% 6% 5% 7% 9% 37%	4580
	11th to 20th	Day	11% 6% 2 6% 5% 4 6% 5% 6% 11% 39%	4580
	21st to end	Day	14% 8% 3 8% 5% 5% 6% 5% 6% 8% 33%	4814
August	1st to 10th	Day	21% 5% 2 6% 4 5% 5% 4 6% 8% 32%	4099
	11th to 20th	Day	13% 5% 2 5% 4 4 5% 4 5% 9% 43%	3730
	21st to end	Day	13% 5% 2 5% 4 3 5% 4 5% 8% 48%	4180
September	1st to 10th	Day	15% 5% 2 6% 4 4 4 4 5% 7% 44%	2280
	11th to 20th	Day	13% 5% 2 4 3 3 4 3 5% 8% 50%	2233
	21st to end	Day	20% 5% 2 6% 5% 4 4 3 5% 6% 40%	2090
October	1st to 10th	Day	19% 6% 2 6% 3 4 4 3 5% 6% 42%	1929
	11th to 20th	Day	15% 5% 2 5% 4 4 4 3 5% 7% 47%	1900
	21st to end	Day	19% 6% 2 4 3 3 3 3 5% 7% 43%	1988
November	1st to 10th	Day	13% 6% 2 4 4 3 3 2 4 6% 53%	1761
	11th to 20th	Day	17% 6% 1 5% 3 4 3 3 6% 5% 47%	1800
	21st to end	Day	16% 6% 2 5% 4 4 4 3 5% 7% 44%	1675
December	1st to 10th	Day	16% 7% 2 5% 3 4 4 3 6% 7% 43%	2600
	11th to 20th	Day	23% 7% 2 4 3 3 4 3 4 5% 42%	2986
	21st to end	Day	18% 6% 3 7% 5% 4 5% 3 5% 7% 36%	3960
January	1st to 10th	Night	13% 6% 2 5% 4 4 3 3 5% 7% 50%	6349
	11th to 20th	Night	13% 8% 3 6% 4 4 4 3 4 6% 45%	6315
	21st to end	Night	19% 8% 2 5% 4 4 4 3 4 6% 42%	6490
February	1st to 10th	Night	17% 8% 3 6% 4 4 4 3 5% 6% 40%	2600
	11th to 20th	Night	17% 7% 3 7% 5% 4 3 3 5% 5% 41%	2370
	21st to end	Night	18% 9% 2 5% 4 4 4 3 5% 6% 42%	1980
March	1st to 10th	Night	19% 8% 2 5% 4 3 4 3 5% 6% 43%	5364
	11th to 20th	Night	13% 8% 2 4 3 4 4 3 4 5% 49%	5035
	21st to end	Night	16% 8% 3 6% 4 4 4 3 4 5% 43%	5086
April	1st to 10th	Night	17% 7% 3 7% 4 5% 4 4 5% 6% 37%	2000
	11th to 20th	Night	17% 7% 2 6% 5% 5% 3 3 6% 7% 40%	1975
	21st to end	Night	19% 6% 2 5% 3 3 4 3 5% 7% 44%	2000
May	1st to 10th	Night	27% 8% 2 6% 4 4 4 3 6% 8% 28%	4075
	11th to 20th	Night	23% 10% 3 6% 4 4 3 3 4 6% 34%	3575
	21st to end	Night	22% 7% 3 5% 4 4 4 3 6% 7% 36%	3926
June	1st to 10th	Night	16% 6% 2 5% 4 4 5% 4 5% 8% 42%	1600
	11th to 20th	Night	14% 5% 2 6% 5% 4 5% 5% 6% 8% 40%	1600
	21st to end	Night	11% 4 2 5% 4 4 6% 4 7% 9% 43%	1600
July	1st to 10th	Night	8% 6% 3 7% 5% 5% 6% 4 7% 9% 39%	2600
	11th to 20th	Night	12% 7% 2 6% 5% 4 5% 5% 8% 10% 37%	2600
	21st to end	Night	16% 7% 2 6% 4 5% 5% 5% 7% 8% 36%	2739
August	1st to 10th	Night	22% 6% 2 6% 4 5% 4 4 7% 8% 31%	2810
	11th to 20th	Night	15% 6% 2 6% 4 5% 5% 4 6% 7% 39%	3084
	21st to end	Night	11% 5% 2 5% 3 4 4 2 6% 8% 50%	3476
September	1st to 10th	Night	15% 6% 3 6% 4 5% 4 4 5% 5% 45%	1900
	11th to 20th	Night	13% 6% 1 4 3 4 4 3 4 7% 51%	1947
	21st to end	Night	19% 6% 2 5% 4 3 4 3 5% 6% 42%	2090
October	1st to 10th	Night	19% 6% 2 6% 3 3 3 3 4 7% 42%	2247
	11th to 20th	Night	15% 5% 2 4 3 3 4 3 4 6% 50%	2280
	21st to end	Night	19% 6% 3 4 3 3 3 3 4 6% 46%	2608
November	1st to 10th	Night	12% 6% 2 5% 3 3 3 3 4 5% 53%	2537
	11th to 20th	Night	18% 8% 2 4 3 2 4 3 4 4 48%	2600
	21st to end	Night	14% 7% 2 5% 3 4 4 3 6% 8% 44%	2720
December	1st to 10th	Night	13% 7% 3 6% 4 4 3 3 5% 6% 46%	4580
	11th to 20th	Night	23% 7% 2 4 3 3 3 3 4 5% 42%	5208
	21st to end	Night	20% 9% 3 6% 4 3 3 2 4 5% 40%	6996

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	37% 4 8% 27% 21% 2	3598
	11th to 20th	Day	45% 4 10% 20% 16% 5%	3600
	21st to end	Day	46% 5% 10% 21% 16% 1	4448
February	1st to 10th	Day	45% 5% 14% 23% 12% 2	1800
	11th to 20th	Day	46% 5% 8% 23% 15% 3	1923
	21st to end	Day	48% 3 11% 22% 13% 3	1650
March	1st to 10th	Day	43% 3 9% 23% 15% 7%	4479
	11th to 20th	Day	39% 5% 13% 26% 12% 5%	4906
	21st to end	Day	42% 4 10% 14% 24% 6%	5832
April	1st to 10th	Day	47% 5% 9% 19% 16% 5%	2400
	11th to 20th	Day	42% 4 13% 20% 18% 3	2374
	21st to end	Day	43% 5% 9% 20% 18% 5%	2400
May	1st to 10th	Day	53% 6% 13% 16% 11% 1	5904
	11th to 20th	Day	51% 5% 9% 21% 13% 1	6322
	21st to end	Day	45% 7% 10% 22% 15% 2	6949
June	1st to 10th	Day	41% 7% 14% 21% 15% 1	2800
	11th to 20th	Day	45% 7% 13% 21% 11% 3	2800
	21st to end	Day	40% 8% 12% 22% 16% 1	2800
July	1st to 10th	Day	42% 10% 13% 20% 14% 2	4510
	11th to 20th	Day	38% 8% 16% 23% 14% 1	4505
	21st to end	Day	47% 7% 11% 17% 16% 2	4661
August	1st to 10th	Day	49% 7% 12% 21% 11%	4085
	11th to 20th	Day	37% 7% 13% 28% 14% 1	3766
	21st to end	Day	34% 6% 10% 28% 21% 2	4180
September	1st to 10th	Day	39% 7% 11% 20% 20% 3	2280
	11th to 20th	Day	33% 5% 11% 23% 24% 4	2233
	21st to end	Day	46% 5% 8% 17% 20% 3	2090
October	1st to 10th	Day	39% 4 9% 18% 24% 5%	3202
	11th to 20th	Day	26% 4 10% 25% 29% 5%	3140
	21st to end	Day	27% 3 13% 25% 27% 4	3252
November	1st to 10th	Day	34% 4 12% 24% 22% 3	1761
	11th to 20th	Day	38% 4 11% 23% 21% 3	1800
	21st to end	Day	39% 4 14% 29% 12% 2	1675
December	1st to 10th	Day	40% 3 16% 27% 13% 2	2600
	11th to 20th	Day	45% 4 12% 26% 12% 2	2986
	21st to end	Day	45% 5% 11% 22% 15% 2	3960
January	1st to 10th	Night	35% 4 9% 27% 21% 5%	6349
	11th to 20th	Night	41% 4 13% 21% 15% 6%	6360
	21st to end	Night	44% 4 9% 21% 17% 4	6490
February	1st to 10th	Night	45% 5% 12% 25% 12% 2	2600
	11th to 20th	Night	45% 4 9% 20% 17% 4	2372
	21st to end	Night	44% 4 8% 22% 19% 4	1980
March	1st to 10th	Night	43% 4 9% 23% 12% 9%	5374
	11th to 20th	Night	38% 5% 14% 24% 15% 4	5036
	21st to end	Night	44% 4 7% 16% 23% 6%	5086
April	1st to 10th	Night	46% 5% 10% 19% 15% 4	2000
	11th to 20th	Night	44% 5% 10% 19% 20% 2	1975
	21st to end	Night	40% 6% 9% 21% 20% 5%	2000
May	1st to 10th	Night	54% 7% 11% 16% 10% 2	4081
	11th to 20th	Night	51% 6% 12% 15% 13% 2	3576
	21st to end	Night	46% 7% 12% 22% 12% 2	3927
June	1st to 10th	Night	41% 6% 10% 22% 20% 2	1600
	11th to 20th	Night	40% 8% 13% 25% 13% 1	1600
	21st to end	Night	35% 9% 15% 25% 15% 1	1600
July	1st to 10th	Night	40% 9% 17% 18% 14% 2	2560
	11th to 20th	Night	40% 9% 14% 24% 13% 1	2552
	21st to end	Night	45% 7% 13% 16% 16% 2	2651
August	1st to 10th	Night	49% 8% 17% 15% 9% 1	2800
	11th to 20th	Night	42% 8% 12% 25% 13% 1	3114
	21st to end	Night	33% 6% 10% 30% 20% 1	3476
September	1st to 10th	Night	40% 7% 10% 20% 21% 2	1900
	11th to 20th	Night	33% 5% 11% 22% 26% 4	1947
	21st to end	Night	42% 5% 8% 22% 21% 2	2090
October	1st to 10th	Night	41% 4 11% 22% 21% 2	3754
	11th to 20th	Night	25% 5% 9% 29% 29% 4	3779
	21st to end	Night	29% 3 11% 32% 22% 3	4294
November	1st to 10th	Night	32% 5% 12% 24% 22% 4	2537
	11th to 20th	Night	41% 4 8% 23% 20% 4	2600
	21st to end	Night	38% 5% 13% 27% 15% 2	2720
December	1st to 10th	Night	40% 4 12% 30% 12% 2	4580
	11th to 20th	Night	45% 4 11% 23% 14% 3	5208
	21st to end	Night	47% 4 9% 20% 16% 3	6996

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	31% 22% 32% 13% 2 1	200
	11th to 20th	Day	34% 30% 26% 10% 1	200
	21st to end	Day	25% 28% 30% 13% 4	327
February	1st to 10th	Day	31% 26% 32% 8% 3	300
	11th to 20th	Day	36% 21% 33% 10% 1	462
	21st to end	Day	33% 22% 26% 15% 3	414
March	1st to 10th	Day	32% 21% 29% 15% 3	500
	11th to 20th	Day	26% 25% 31% 14% 2 1	500
	21st to end	Day	29% 23% 31% 11% 5% 1	550
April	1st to 10th	Day	32% 20% 30% 12% 5% 1	500
	11th to 20th	Day	26% 23% 29% 13% 8% 1	492
	21st to end	Day	28% 19% 31% 18% 3 2	500
May	1st to 10th	Day	33% 18% 28% 15% 5% 2	503
	11th to 20th	Day	24% 14% 34% 19% 7% 1	527
	21st to end	Day	23% 9% 26% 25% 15% 2	573
June	1st to 10th	Day	18% 13% 31% 24% 12% 2	530
	11th to 20th	Day	20% 12% 28% 27% 10% 2	530
	21st to end	Day	18% 9% 33% 27% 12% 2	530
July	1st to 10th	Day	12% 6% 25% 31% 20% 6%	525
	11th to 20th	Day	9% 5% 26% 34% 20% 6%	524
	21st to end	Day	16% 5% 32% 30% 13% 4	532
August	1st to 10th	Day	13% 5% 27% 32% 17% 6%	486
	11th to 20th	Day	14% 5% 23% 32% 19% 6%	479
	21st to end	Day	14% 7% 28% 29% 15% 8%	539
September	1st to 10th	Day	18% 9% 25% 26% 15% 7%	490
	11th to 20th	Day	15% 6% 26% 26% 16% 10%	490
	21st to end	Day	23% 12% 27% 22% 12% 5%	490
October	1st to 10th	Day	24% 9% 27% 20% 13% 7%	490
	11th to 20th	Day	18% 16% 29% 24% 10% 2	490
	21st to end	Day	24% 15% 31% 18% 11% 1	484
November	1st to 10th	Day	20% 12% 31% 22% 12% 3	395
	11th to 20th	Day	27% 15% 32% 21% 5% 1	400
	21st to end	Day	24% 17% 37% 16% 5%	275
December	1st to 10th	Day	30% 26% 28% 11% 6%	200
	11th to 20th	Day	39% 23% 23% 12% 5%	200
	21st to end	Day	30% 17% 30% 15% 8% 1	220
January	1st to 10th	Night	23% 20% 38% 17% 2	800
	11th to 20th	Night	27% 18% 33% 20% 3	800
	21st to end	Night	21% 19% 40% 20% 1	880
February	1st to 10th	Night	24% 18% 35% 21% 2	800
	11th to 20th	Night	27% 21% 37% 14% 1	783
	21st to end	Night	28% 16% 37% 17% 2	660
March	1st to 10th	Night	24% 21% 32% 20% 4	800
	11th to 20th	Night	25% 19% 34% 19% 3	800
	21st to end	Night	22% 17% 39% 17% 4	880
April	1st to 10th	Night	23% 21% 36% 17% 4	800
	11th to 20th	Night	24% 14% 35% 21% 6%	791
	21st to end	Night	21% 15% 34% 25% 5%	800
May	1st to 10th	Night	26% 14% 30% 23% 6%	621
	11th to 20th	Night	25% 8% 35% 25% 7%	394
	21st to end	Night	19% 7% 25% 37% 12% 1	433
June	1st to 10th	Night	18% 5% 29% 35% 12% 1	400
	11th to 20th	Night	16% 5% 29% 40% 11%	400
	21st to end	Night	11% 4 27% 46% 12% 1	400
July	1st to 10th	Night	11% 4 24% 39% 20% 2	390
	11th to 20th	Night	12% 4 26% 39% 19% 1	388
	21st to end	Night	12% 3 24% 45% 15% 1	416
August	1st to 10th	Night	15% 1 17% 44% 20% 2	552
	11th to 20th	Night	15% 3 20% 36% 25% 2	737
	21st to end	Night	16% 3 20% 38% 21% 1	836
September	1st to 10th	Night	17% 4 26% 34% 17% 2	760
	11th to 20th	Night	16% 3 21% 34% 21% 4	760
	21st to end	Night	22% 6% 24% 31% 16% 1	760
October	1st to 10th	Night	22% 9% 26% 26% 16% 2	760
	11th to 20th	Night	18% 11% 29% 30% 11%	760
	21st to end	Night	23% 12% 31% 23% 10%	836
November	1st to 10th	Night	15% 11% 35% 27% 11% 1	780
	11th to 20th	Night	23% 16% 30% 25% 7%	800
	21st to end	Night	19% 17% 35% 23% 6% 1	800
December	1st to 10th	Night	25% 17% 32% 21% 5% 1	800
	11th to 20th	Night	23% 15% 35% 22% 4	800
	21st to end	Night	25% 15% 32% 25% 3	880

Page generated at 2025-07-18 01:10:01. Version ac07

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