Chestnut Ridge Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Chestnut Ridge Park clear sky chart from 2005-11-06 to 2024-11-05.

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% 11% 4 8% 5% 4 4 3 5% 7% 31%	101035
	Night	18% 13% 4 8% 4 4 4 3 5% 6% 31%	97921
Transparency	Day	51% 6% 10% 21% 11% 1	104685
	Night	53% 5% 9% 20% 11% 2	102410
Seeing	Day	27% 14% 25% 20% 10% 4	14816
	Night	26% 13% 23% 26% 12% 1	24548

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% 21% 8% 13% 6% 3 3 2 4 4 18%	2836
	11th to 20th	Day	14% 22% 11% 16% 8% 4 3 2 3 3 15%	2840
	21st to end	Day	23% 20% 9% 10% 6% 4 3 2 3 4 15%	3124
February	1st to 10th	Day	20% 17% 5% 11% 6% 4 3 3 4 5% 21%	1710
	11th to 20th	Day	19% 16% 7% 12% 5% 5% 4 3 4 5% 22%	1663
	21st to end	Day	22% 18% 5% 10% 4 3 3 2 4 4 24%	1596
March	1st to 10th	Day	20% 16% 6% 7% 4 3 3 3 4 7% 28%	3435
	11th to 20th	Day	16% 12% 5% 9% 4 4 4 3 4 7% 33%	3480
	21st to end	Day	22% 13% 3 8% 5% 4 4 3 4 5% 30%	3815
April	1st to 10th	Day	18% 15% 3 7% 5% 4 5% 4 6% 6% 29%	2194
	11th to 20th	Day	17% 12% 3 7% 4 4 5% 3 4 6% 34%	2254
	21st to end	Day	22% 10% 3 6% 4 4 4 4 5% 6% 31%	2460
May	1st to 10th	Day	24% 11% 3 8% 5% 5% 4 4 5% 6% 25%	4082
	11th to 20th	Day	21% 9% 2 8% 5% 4 5% 4 6% 7% 29%	4081
	21st to end	Day	14% 7% 3 6% 5% 5% 5% 4 6% 9% 34%	4666
June	1st to 10th	Day	16% 7% 3 7% 5% 4 5% 5% 7% 9% 34%	2660
	11th to 20th	Day	15% 7% 3 6% 6% 6% 6% 4 7% 8% 33%	2660
	21st to end	Day	16% 6% 2 6% 5% 5% 6% 4 7% 9% 34%	2660
July	1st to 10th	Day	11% 6% 2 6% 5% 5% 6% 5% 6% 8% 40%	4222
	11th to 20th	Day	13% 7% 2 6% 4 5% 5% 4 6% 10% 38%	4120
	21st to end	Day	17% 10% 3 7% 5% 5% 5% 4 6% 8% 32%	4466
August	1st to 10th	Day	15% 8% 3 8% 5% 5% 6% 5% 7% 9% 30%	4104
	11th to 20th	Day	15% 6% 3 6% 5% 4 5% 5% 6% 9% 37%	4044
	21st to end	Day	9% 4 2 5% 4 4 5% 4 7% 10% 46%	4260
September	1st to 10th	Day	16% 6% 2 6% 4 4 4 3 5% 6% 45%	2280
	11th to 20th	Day	14% 7% 2 6% 4 4 4 4 5% 8% 43%	2109
	21st to end	Day	20% 8% 3 7% 5% 4 4 4 4 7% 34%	2080
October	1st to 10th	Day	17% 7% 3 6% 4 4 4 3 5% 6% 42%	1900
	11th to 20th	Day	20% 10% 2 7% 4 4 4 3 4 5% 38%	1900
	21st to end	Day	24% 12% 3 5% 3 3 3 2 3 5% 36%	2090
November	1st to 10th	Day	13% 11% 2 6% 4 4 3 3 4 7% 43%	1870
	11th to 20th	Day	16% 16% 4 7% 4 3 3 4 6% 6% 31%	1606
	21st to end	Day	20% 18% 5% 8% 4 3 3 3 4 5% 27%	1520
December	1st to 10th	Day	23% 18% 8% 11% 5% 4 4 3 4 4 17%	1520
	11th to 20th	Day	20% 20% 6% 11% 4 3 2 2 3 5% 23%	1910
	21st to end	Day	21% 22% 8% 10% 4 4 3 3 4 5% 16%	2818
January	1st to 10th	Night	17% 24% 8% 12% 4 5% 3 3 3 4 17%	4109
	11th to 20th	Night	18% 19% 9% 14% 5% 6% 4 2 3 3 16%	4120
	21st to end	Night	27% 19% 8% 10% 6% 3 2 2 2 3 18%	4532
February	1st to 10th	Night	19% 16% 6% 11% 5% 3 4 3 4 4 26%	2470
	11th to 20th	Night	20% 18% 4 12% 5% 5% 4 2 4 4 22%	2403
	21st to end	Night	22% 16% 4 10% 4 3 4 3 5% 5% 24%	1851
March	1st to 10th	Night	23% 13% 4 6% 5% 3 3 3 4 6% 29%	3418
	11th to 20th	Night	17% 17% 6% 7% 4 3 3 3 3 5% 31%	3480
	21st to end	Night	18% 12% 3 8% 4 3 3 3 4 6% 37%	3817
April	1st to 10th	Night	20% 16% 4 7% 4 3 4 2 4 5% 31%	1984
	11th to 20th	Night	18% 9% 3 6% 4 4 4 3 6% 7% 35%	1875
	21st to end	Night	16% 9% 4 7% 5% 3 4 3 5% 7% 37%	1737
May	1st to 10th	Night	29% 11% 3 7% 5% 4 4 3 5% 5% 24%	2813
	11th to 20th	Night	20% 9% 3 8% 4 5% 3 3 4 7% 33%	2812
	21st to end	Night	15% 10% 3 7% 4 4 4 4 6% 8% 35%	2871
June	1st to 10th	Night	12% 6% 2 7% 5% 4 5% 3 6% 8% 42%	1520
	11th to 20th	Night	12% 7% 3 6% 5% 5% 4 5% 7% 9% 37%	1520
	21st to end	Night	14% 6% 2 5% 4 4 5% 5% 7% 10% 38%	1520
July	1st to 10th	Night	13% 8% 3 8% 4 5% 5% 4 6% 8% 36%	2733
	11th to 20th	Night	14% 7% 3 6% 5% 4 4 5% 5% 9% 38%	2840
	21st to end	Night	16% 9% 3 6% 4 4 5% 4 6% 7% 36%	3087
August	1st to 10th	Night	14% 8% 3 8% 4 5% 5% 4 8% 9% 31%	2825
	11th to 20th	Night	18% 7% 2 6% 5% 3 4 4 5% 6% 41%	2785
	21st to end	Night	8% 5% 2 5% 4 4 5% 5% 6% 10% 46%	3362
September	1st to 10th	Night	14% 6% 2 7% 3 4 4 3 6% 6% 44%	1900
	11th to 20th	Night	13% 5% 2 5% 3 3 4 3 6% 7% 51%	2067
	21st to end	Night	16% 8% 3 7% 4 4 5% 3 5% 6% 40%	2099
October	1st to 10th	Night	18% 6% 2 5% 3 3 4 4 4 7% 44%	2280
	11th to 20th	Night	18% 8% 2 5% 4 4 4 3 6% 6% 40%	2280
	21st to end	Night	26% 9% 2 4 3 3 3 3 4 5% 37%	2508
November	1st to 10th	Night	14% 10% 3 6% 3 4 4 3 4 6% 44%	2306
	11th to 20th	Night	20% 14% 4 8% 4 3 3 3 4 5% 31%	2572
	21st to end	Night	18% 17% 5% 8% 5% 3 4 3 4 4 28%	2660
December	1st to 10th	Night	22% 20% 7% 10% 4 4 4 2 3 4 19%	2660
	11th to 20th	Night	20% 19% 8% 10% 4 4 2 3 4 4 22%	3285
	21st to end	Night	21% 21% 8% 9% 5% 4 3 3 4 5% 17%	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	70% 4 9% 12% 4 1	2837
	11th to 20th	Day	77% 3 6% 9% 5%	2840
	21st to end	Day	74% 3 6% 13% 3	3124
February	1st to 10th	Day	66% 4 9% 15% 6%	1710
	11th to 20th	Day	66% 3 8% 13% 9%	1672
	21st to end	Day	64% 4 8% 13% 9% 2	1596
March	1st to 10th	Day	58% 4 9% 21% 8%	3435
	11th to 20th	Day	51% 6% 9% 25% 8% 1	3480
	21st to end	Day	56% 4 7% 20% 12% 1	3815
April	1st to 10th	Day	55% 5% 9% 18% 11% 2	2194
	11th to 20th	Day	51% 5% 10% 15% 17% 2	2254
	21st to end	Day	53% 5% 10% 21% 10% 2	2460
May	1st to 10th	Day	58% 6% 8% 20% 7% 1	4120
	11th to 20th	Day	52% 8% 10% 22% 7% 1	4085
	21st to end	Day	43% 8% 15% 21% 11% 2	4680
June	1st to 10th	Day	44% 9% 12% 23% 12% 1	2660
	11th to 20th	Day	46% 8% 12% 22% 10% 1	2660
	21st to end	Day	44% 9% 12% 24% 11% 1	2660
July	1st to 10th	Day	41% 7% 13% 23% 14% 2	4157
	11th to 20th	Day	40% 7% 12% 29% 12% 1	4051
	21st to end	Day	49% 6% 9% 22% 13% 1	4324
August	1st to 10th	Day	48% 8% 13% 23% 7%	4091
	11th to 20th	Day	43% 6% 10% 31% 11%	4083
	21st to end	Day	32% 8% 16% 28% 15% 1	4260
September	1st to 10th	Day	39% 5% 10% 22% 20% 3	2280
	11th to 20th	Day	38% 6% 11% 27% 15% 3	2109
	21st to end	Day	50% 5% 10% 18% 16% 1	2080
October	1st to 10th	Day	35% 4 8% 29% 22% 3	3160
	11th to 20th	Day	44% 5% 9% 22% 13% 7%	3140
	21st to end	Day	37% 3 9% 28% 22% 1	3428
November	1st to 10th	Day	43% 4 9% 23% 17% 4	1870
	11th to 20th	Day	53% 5% 10% 17% 14% 3	1606
	21st to end	Day	61% 3 10% 15% 11%	1520
December	1st to 10th	Day	72% 4 7% 12% 4 1	1520
	11th to 20th	Day	66% 3 7% 18% 5% 1	1906
	21st to end	Day	70% 5% 9% 11% 5%	2818
January	1st to 10th	Night	72% 3 6% 12% 5% 1	4109
	11th to 20th	Night	74% 3 9% 11% 2	4120
	21st to end	Night	75% 3 5% 13% 4 1	4532
February	1st to 10th	Night	62% 4 9% 16% 8%	2470
	11th to 20th	Night	67% 3 8% 14% 8%	2405
	21st to end	Night	62% 5% 8% 15% 9% 2	1851
March	1st to 10th	Night	57% 4 7% 24% 8% 1	3418
	11th to 20th	Night	56% 5% 7% 25% 6% 1	3480
	21st to end	Night	50% 4 7% 24% 13% 2	3817
April	1st to 10th	Night	57% 4 8% 17% 13% 2	1984
	11th to 20th	Night	47% 5% 11% 18% 15% 4	1875
	21st to end	Night	46% 5% 11% 24% 11% 3	1737
May	1st to 10th	Night	60% 6% 8% 16% 8% 2	2840
	11th to 20th	Night	50% 8% 10% 22% 8% 1	2813
	21st to end	Night	44% 8% 13% 22% 9% 4	2878
June	1st to 10th	Night	40% 8% 13% 25% 13% 1	1520
	11th to 20th	Night	41% 9% 14% 23% 12% 1	1520
	21st to end	Night	39% 8% 14% 23% 14% 1	1520
July	1st to 10th	Night	44% 7% 11% 22% 13% 3	2688
	11th to 20th	Night	41% 8% 11% 26% 13% 1	2786
	21st to end	Night	46% 6% 9% 20% 17% 2	2988
August	1st to 10th	Night	47% 8% 18% 20% 7%	2814
	11th to 20th	Night	44% 5% 9% 23% 17% 1	2812
	21st to end	Night	32% 8% 12% 33% 13% 2	3362
September	1st to 10th	Night	39% 6% 11% 22% 17% 5%	1900
	11th to 20th	Night	32% 5% 13% 26% 22% 2	2067
	21st to end	Night	44% 5% 11% 22% 17% 1	2099
October	1st to 10th	Night	36% 4 8% 29% 19% 4	3800
	11th to 20th	Night	39% 4 8% 23% 16% 9%	3779
	21st to end	Night	38% 3 7% 27% 24% 2	4120
November	1st to 10th	Night	42% 4 11% 20% 18% 5%	2306
	11th to 20th	Night	55% 4 7% 17% 13% 2	2572
	21st to end	Night	59% 4 8% 18% 9% 2	2660
December	1st to 10th	Night	70% 4 7% 14% 4 1	2660
	11th to 20th	Night	66% 4 8% 15% 6% 1	3288
	21st to end	Night	70% 5% 9% 11% 5%	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	38% 31% 17% 10% 4	270
	11th to 20th	Day	43% 26% 25% 6%	270
	21st to end	Day	39% 27% 27% 4 3	297
February	1st to 10th	Day	37% 28% 27% 7% 1	270
	11th to 20th	Day	46% 26% 23% 4	270
	21st to end	Day	45% 25% 23% 6% 1	280
March	1st to 10th	Day	35% 22% 28% 12% 4	460
	11th to 20th	Day	37% 20% 27% 11% 3 1	460
	21st to end	Day	37% 20% 26% 13% 4	506
April	1st to 10th	Day	35% 20% 24% 15% 5% 1	460
	11th to 20th	Day	27% 20% 27% 15% 6% 4	452
	21st to end	Day	34% 18% 26% 15% 5% 1	460
May	1st to 10th	Day	32% 17% 27% 13% 7% 4	463
	11th to 20th	Day	27% 15% 28% 18% 9% 3	487
	21st to end	Day	17% 11% 28% 23% 14% 7%	529
June	1st to 10th	Day	19% 10% 26% 25% 15% 4	490
	11th to 20th	Day	20% 10% 23% 26% 16% 4	490
	21st to end	Day	17% 10% 28% 27% 14% 3	490
July	1st to 10th	Day	18% 5% 24% 27% 15% 12%	485
	11th to 20th	Day	13% 7% 24% 32% 17% 7%	484
	21st to end	Day	20% 7% 25% 24% 18% 5%	532
August	1st to 10th	Day	14% 9% 22% 30% 18% 7%	486
	11th to 20th	Day	20% 3 22% 28% 18% 8%	479
	21st to end	Day	14% 5% 23% 28% 20% 10%	539
September	1st to 10th	Day	18% 7% 20% 27% 18% 9%	490
	11th to 20th	Day	15% 3 21% 29% 22% 9%	490
	21st to end	Day	27% 10% 25% 22% 13% 3	490
October	1st to 10th	Day	20% 10% 23% 27% 17% 3	490
	11th to 20th	Day	27% 12% 27% 26% 7% 1	490
	21st to end	Day	33% 15% 27% 17% 8%	539
November	1st to 10th	Day	21% 15% 28% 23% 9% 3	444
	11th to 20th	Day	34% 19% 26% 12% 7% 1	221
	21st to end	Day	33% 22% 31% 11% 2 1	180
December	1st to 10th	Day	33% 27% 28% 6% 3 2	180
	11th to 20th	Day	44% 21% 26% 7% 2	180
	21st to end	Day	40% 27% 17% 13% 3	213
January	1st to 10th	Night	35% 23% 25% 14% 3	760
	11th to 20th	Night	38% 19% 28% 14% 1	760
	21st to end	Night	34% 24% 25% 16% 1	836
February	1st to 10th	Night	30% 20% 28% 20% 2	760
	11th to 20th	Night	36% 25% 28% 11%	743
	21st to end	Night	33% 23% 27% 15% 1	628
March	1st to 10th	Night	29% 20% 28% 19% 3	760
	11th to 20th	Night	34% 17% 24% 18% 6%	760
	21st to end	Night	28% 19% 30% 19% 4	836
April	1st to 10th	Night	31% 16% 28% 19% 5%	760
	11th to 20th	Night	24% 13% 30% 22% 10% 1	751
	21st to end	Night	22% 12% 31% 27% 8%	597
May	1st to 10th	Night	26% 9% 25% 29% 10% 1	570
	11th to 20th	Night	24% 8% 24% 31% 12% 1	561
	21st to end	Night	14% 6% 20% 32% 26% 3	499
June	1st to 10th	Night	14% 4 21% 40% 20% 1	380
	11th to 20th	Night	12% 6% 21% 39% 21% 2	380
	21st to end	Night	15% 5% 21% 42% 17% 1	380
July	1st to 10th	Night	16% 3 14% 36% 26% 4	487
	11th to 20th	Night	14% 4 14% 38% 28% 3	552
	21st to end	Night	16% 2 14% 37% 28% 2	624
August	1st to 10th	Night	13% 3 12% 43% 26% 3	567
	11th to 20th	Night	17% 4 10% 37% 28% 3	564
	21st to end	Night	13% 3 13% 39% 28% 3	761
September	1st to 10th	Night	18% 3 17% 32% 26% 4	760
	11th to 20th	Night	16% 3 19% 33% 25% 4	760
	21st to end	Night	20% 9% 19% 30% 19% 2	760
October	1st to 10th	Night	19% 8% 21% 29% 19% 3	760
	11th to 20th	Night	25% 10% 23% 30% 11% 1	760
	21st to end	Night	31% 11% 22% 26% 8%	836
November	1st to 10th	Night	22% 10% 23% 33% 11% 1	760
	11th to 20th	Night	31% 15% 24% 22% 6% 1	760
	21st to end	Night	29% 16% 28% 22% 4 1	760
December	1st to 10th	Night	37% 17% 24% 17% 4	760
	11th to 20th	Night	32% 21% 24% 19% 4	760
	21st to end	Night	33% 18% 28% 19% 1	836

Page generated at 2024-11-03 02:11:15. Version ac07

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