Peck Farm Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Peck Farm Park clear sky chart from 2005-11-06 to 2026-03-03.

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	12% 9% 3 8% 5% 5% 5% 4 6% 7% 36%	130975
	Night	13% 10% 4 8% 5% 4 4 3 5% 6% 38%	130484
Transparency	Day	45% 6% 11% 23% 13% 2	134496
	Night	45% 5% 11% 23% 14% 2	135038
Seeing	Day	17% 13% 30% 24% 12% 4	17555
	Night	17% 11% 31% 29% 11% 1	27546

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	13% 12% 6% 12% 6% 6% 5% 4 6% 6% 24%	4691
	11th to 20th	Day	8% 12% 6% 13% 5% 5% 5% 6% 6% 4 30%	4710
	21st to end	Day	12% 15% 5% 10% 5% 4 4 3 5% 6% 30%	5371
February	1st to 10th	Day	14% 14% 5% 9% 6% 6% 5% 4 5% 6% 25%	1916
	11th to 20th	Day	13% 12% 5% 9% 5% 4 5% 3 4 6% 34%	2048
	21st to end	Day	13% 13% 5% 10% 5% 3 4 3 5% 6% 31%	1730
March	1st to 10th	Day	16% 11% 3 7% 4 3 3 2 4 5% 41%	4500
	11th to 20th	Day	9% 6% 3 7% 5% 5% 5% 4 6% 8% 43%	4692
	21st to end	Day	19% 14% 5% 13% 6% 5% 5% 4 5% 5% 20%	5967
April	1st to 10th	Day	17% 13% 4 8% 6% 4 4 4 5% 7% 30%	2400
	11th to 20th	Day	15% 11% 3 6% 5% 5% 5% 4 6% 6% 35%	2374
	21st to end	Day	19% 9% 3 7% 5% 6% 4 3 5% 6% 33%	2492
May	1st to 10th	Day	16% 8% 3 6% 5% 5% 5% 4 6% 8% 35%	5862
	11th to 20th	Day	14% 6% 2 6% 5% 5% 5% 4 5% 7% 40%	6221
	21st to end	Day	13% 8% 3 7% 4 5% 5% 4 7% 9% 37%	6935
June	1st to 10th	Day	9% 5% 3 5% 5% 5% 4 4 6% 8% 46%	2800
	11th to 20th	Day	9% 6% 2 6% 5% 4 5% 4 7% 8% 44%	2800
	21st to end	Day	10% 6% 2 6% 5% 5% 5% 5% 7% 8% 39%	2800
July	1st to 10th	Day	9% 7% 2 7% 5% 6% 6% 5% 8% 9% 35%	6360
	11th to 20th	Day	8% 6% 3 6% 4 4 5% 5% 7% 11% 40%	6360
	21st to end	Day	10% 7% 3 7% 6% 5% 5% 4 7% 9% 37%	6924
August	1st to 10th	Day	8% 5% 2 7% 4 5% 5% 5% 7% 9% 43%	4476
	11th to 20th	Day	10% 5% 2 6% 4 4 5% 5% 7% 10% 41%	3849
	21st to end	Day	7% 5% 2 6% 4 4 5% 4 7% 9% 47%	4312
September	1st to 10th	Day	11% 6% 2 6% 4 5% 5% 4 6% 8% 46%	2400
	11th to 20th	Day	10% 5% 1 4 3 4 4 3 5% 7% 54%	2285
	21st to end	Day	9% 7% 2 6% 5% 4 4 4 6% 8% 45%	2200
October	1st to 10th	Day	11% 7% 2 6% 5% 4 3 3 5% 6% 47%	2128
	11th to 20th	Day	17% 9% 3 7% 5% 5% 3 4 5% 8% 36%	2000
	21st to end	Day	18% 9% 3 7% 4 4 3 4 4 6% 38%	1981
November	1st to 10th	Day	11% 9% 3 7% 4 4 4 4 5% 6% 44%	1852
	11th to 20th	Day	15% 13% 4 8% 5% 3 4 3 5% 7% 33%	1890
	21st to end	Day	17% 12% 4 10% 5% 3 4 2 5% 4 34%	1801
December	1st to 10th	Day	9% 10% 4 10% 5% 4 4 3 4 5% 43%	2690
	11th to 20th	Day	12% 16% 5% 13% 6% 5% 6% 4 5% 7% 24%	3088
	21st to end	Day	24% 23% 7% 12% 6% 4 4 2 3 4 11%	4070
January	1st to 10th	Night	12% 14% 6% 13% 5% 5% 4 3 4 4 30%	8232
	11th to 20th	Night	10% 14% 6% 15% 7% 6% 5% 4 6% 4 23%	8280
	21st to end	Night	14% 14% 6% 8% 5% 4 4 3 5% 5% 32%	8841
February	1st to 10th	Night	14% 14% 4 9% 6% 4 4 3 4 6% 32%	2702
	11th to 20th	Night	13% 12% 3 8% 5% 4 4 3 4 7% 37%	2458
	21st to end	Night	16% 11% 4 9% 4 4 3 3 5% 6% 36%	2076
March	1st to 10th	Night	16% 10% 4 6% 4 4 3 2 5% 4 41%	5398
	11th to 20th	Night	10% 7% 2 7% 4 4 4 3 5% 7% 47%	5310
	21st to end	Night	19% 11% 5% 10% 5% 4 4 3 5% 5% 28%	4962
April	1st to 10th	Night	16% 9% 2 7% 4 4 4 3 5% 6% 39%	2000
	11th to 20th	Night	18% 10% 3 6% 5% 3 4 3 5% 6% 38%	1975
	21st to end	Night	16% 8% 3 8% 4 4 4 3 6% 7% 36%	1906
May	1st to 10th	Night	17% 8% 3 7% 4 4 4 4 5% 7% 36%	4033
	11th to 20th	Night	11% 6% 2 5% 3 4 4 4 7% 8% 44%	3686
	21st to end	Night	15% 8% 3 6% 4 4 4 3 5% 7% 40%	3942
June	1st to 10th	Night	10% 5% 2 5% 4 4 4 4 6% 9% 48%	1600
	11th to 20th	Night	8% 6% 2 6% 4 5% 4 4 8% 8% 46%	1600
	21st to end	Night	9% 6% 2 6% 5% 5% 5% 5% 7% 7% 43%	1600
July	1st to 10th	Night	10% 6% 3 7% 5% 5% 6% 4 7% 8% 40%	3618
	11th to 20th	Night	7% 5% 2 6% 4 4 5% 3 6% 9% 49%	3617
	21st to end	Night	8% 6% 2 7% 5% 5% 5% 5% 6% 8% 43%	3947
August	1st to 10th	Night	5% 4 2 6% 5% 5% 4 4 7% 9% 48%	2674
	11th to 20th	Night	8% 5% 2 6% 4 4 4 4 7% 8% 49%	3200
	21st to end	Night	8% 4 2 5% 3 4 4 3 5% 8% 53%	3586
September	1st to 10th	Night	9% 5% 2 5% 3 3 3 3 4 7% 55%	2000
	11th to 20th	Night	9% 4 2 5% 3 4 3 3 6% 8% 55%	2095
	21st to end	Night	9% 7% 2 6% 5% 4 4 3 6% 8% 47%	2200
October	1st to 10th	Night	11% 5% 2 5% 4 3 4 4 5% 6% 53%	2270
	11th to 20th	Night	18% 6% 3 5% 5% 3 3 3 4 6% 45%	2400
	21st to end	Night	20% 9% 2 6% 4 3 4 3 4 7% 38%	2857
November	1st to 10th	Night	12% 8% 3 6% 4 3 3 3 5% 6% 47%	2666
	11th to 20th	Night	15% 11% 4 7% 5% 3 5% 3 5% 6% 37%	2730
	21st to end	Night	17% 11% 4 9% 5% 4 3 3 5% 5% 36%	2814
December	1st to 10th	Night	12% 10% 3 8% 4 4 4 3 5% 7% 41%	4720
	11th to 20th	Night	17% 15% 4 8% 5% 4 3 3 4 5% 30%	5339
	21st to end	Night	24% 19% 6% 10% 5% 5% 4 3 4 5% 17%	7150

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	59% 4 15% 15% 6%	4692
	11th to 20th	Day	54% 5% 9% 16% 13% 4	4710
	21st to end	Day	54% 4 12% 20% 8%	5371
February	1st to 10th	Day	58% 6% 12% 14% 9% 2	1916
	11th to 20th	Day	51% 5% 10% 23% 9% 2	2058
	21st to end	Day	54% 5% 11% 19% 9% 2	1730
March	1st to 10th	Day	46% 5% 9% 25% 12% 3	4500
	11th to 20th	Day	39% 5% 11% 32% 11% 1	4692
	21st to end	Day	65% 6% 10% 12% 6% 1	5969
April	1st to 10th	Day	54% 5% 10% 20% 11%	2400
	11th to 20th	Day	48% 6% 9% 22% 12% 3	2374
	21st to end	Day	51% 6% 11% 18% 12% 2	2492
May	1st to 10th	Day	45% 7% 10% 24% 13% 1	5897
	11th to 20th	Day	42% 7% 9% 25% 16% 1	6225
	21st to end	Day	41% 6% 11% 25% 13% 3	6949
June	1st to 10th	Day	35% 7% 12% 28% 17% 2	2800
	11th to 20th	Day	35% 8% 11% 24% 19% 3	2800
	21st to end	Day	40% 8% 13% 23% 14% 3	2800
July	1st to 10th	Day	41% 7% 12% 24% 14% 1	6291
	11th to 20th	Day	36% 6% 14% 27% 16% 1	6285
	21st to end	Day	41% 7% 15% 21% 15% 2	6728
August	1st to 10th	Day	35% 7% 16% 29% 13% 1	4461
	11th to 20th	Day	35% 7% 12% 30% 15% 1	3885
	21st to end	Day	32% 6% 13% 28% 19% 2	4311
September	1st to 10th	Day	35% 6% 11% 26% 18% 4	2400
	11th to 20th	Day	29% 6% 11% 29% 23% 3	2285
	21st to end	Day	36% 7% 8% 27% 20% 1	2200
October	1st to 10th	Day	25% 4 7% 30% 32% 2	3466
	11th to 20th	Day	32% 4 11% 27% 25% 1	3240
	21st to end	Day	42% 4 9% 28% 14% 3	3181
November	1st to 10th	Day	40% 5% 13% 24% 15% 2	1852
	11th to 20th	Day	52% 4 10% 22% 10% 1	1890
	21st to end	Day	54% 4 11% 23% 8%	1801
December	1st to 10th	Day	44% 4 16% 27% 8% 1	2690
	11th to 20th	Day	59% 4 13% 17% 6% 1	3085
	21st to end	Day	78% 4 6% 8% 4	4070
January	1st to 10th	Night	56% 5% 11% 19% 9%	8233
	11th to 20th	Night	62% 4 10% 11% 13% 1	8280
	21st to end	Night	54% 3 11% 21% 10% 1	8841
February	1st to 10th	Night	55% 4 11% 17% 12% 1	2702
	11th to 20th	Night	47% 5% 10% 23% 13% 1	2459
	21st to end	Night	49% 5% 12% 19% 11% 3	2076
March	1st to 10th	Night	46% 4 11% 24% 11% 4	5398
	11th to 20th	Night	36% 5% 11% 31% 14% 3	5310
	21st to end	Night	58% 5% 9% 19% 9% 1	4962
April	1st to 10th	Night	45% 5% 12% 23% 13% 2	2000
	11th to 20th	Night	46% 5% 8% 21% 16% 4	1975
	21st to end	Night	46% 7% 11% 22% 12% 3	1906
May	1st to 10th	Night	47% 6% 11% 18% 15% 3	4060
	11th to 20th	Night	34% 9% 14% 25% 14% 4	3687
	21st to end	Night	42% 7% 9% 23% 16% 4	3950
June	1st to 10th	Night	33% 6% 12% 26% 19% 3	1600
	11th to 20th	Night	33% 6% 11% 26% 21% 3	1600
	21st to end	Night	37% 9% 14% 21% 17% 2	1600
July	1st to 10th	Night	40% 6% 13% 24% 14% 3	3580
	11th to 20th	Night	31% 6% 13% 30% 19% 1	3572
	21st to end	Night	36% 7% 14% 22% 18% 3	3832
August	1st to 10th	Night	30% 8% 15% 28% 18% 1	2665
	11th to 20th	Night	30% 7% 14% 30% 18% 1	3230
	21st to end	Night	28% 6% 12% 34% 17% 4	3586
September	1st to 10th	Night	29% 6% 11% 28% 23% 3	2000
	11th to 20th	Night	27% 5% 8% 33% 25% 2	2095
	21st to end	Night	35% 6% 10% 29% 17% 2	2200
October	1st to 10th	Night	22% 4 7% 37% 28% 2	3712
	11th to 20th	Night	35% 4 7% 23% 28% 2	3899
	21st to end	Night	41% 4 8% 26% 18% 3	4607
November	1st to 10th	Night	38% 5% 9% 27% 18% 3	2666
	11th to 20th	Night	48% 4 11% 22% 12% 2	2730
	21st to end	Night	51% 5% 11% 22% 11%	2814
December	1st to 10th	Night	43% 4 14% 27% 10% 2	4720
	11th to 20th	Night	57% 4 12% 16% 10% 1	5341
	21st to end	Night	70% 4 8% 11% 6%	7150

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	22% 16% 38% 20% 4 1	330
	11th to 20th	Day	23% 19% 40% 14% 4 1	330
	21st to end	Day	22% 25% 31% 18% 3 1	363
February	1st to 10th	Day	22% 22% 37% 16% 3	330
	11th to 20th	Day	25% 20% 34% 17% 3	330
	21st to end	Day	25% 21% 41% 11% 2	273
March	1st to 10th	Day	23% 25% 37% 15% 1	306
	11th to 20th	Day	29% 19% 34% 14% 4 1	313
	21st to end	Day	29% 16% 31% 17% 5% 1	550
April	1st to 10th	Day	25% 16% 33% 21% 5%	500
	11th to 20th	Day	22% 25% 23% 19% 9% 2	492
	21st to end	Day	23% 16% 30% 23% 7% 1	500
May	1st to 10th	Day	20% 16% 31% 23% 9% 2	503
	11th to 20th	Day	20% 12% 31% 23% 11% 3	679
	21st to end	Day	17% 10% 31% 23% 14% 5%	789
June	1st to 10th	Day	11% 10% 31% 28% 15% 5%	730
	11th to 20th	Day	12% 8% 34% 28% 15% 3	730
	21st to end	Day	11% 10% 30% 31% 13% 4	730
July	1st to 10th	Day	9% 4 23% 31% 20% 13%	721
	11th to 20th	Day	10% 7% 26% 32% 16% 8%	718
	21st to end	Day	9% 4 28% 35% 18% 6%	794
August	1st to 10th	Day	8% 4 21% 35% 22% 9%	688
	11th to 20th	Day	10% 6% 20% 28% 24% 11%	519
	21st to end	Day	7% 5% 19% 34% 25% 10%	583
September	1st to 10th	Day	13% 7% 22% 30% 22% 6%	530
	11th to 20th	Day	9% 4 18% 34% 25% 9%	530
	21st to end	Day	12% 13% 26% 25% 18% 7%	530
October	1st to 10th	Day	14% 10% 27% 29% 16% 4	458
	11th to 20th	Day	19% 24% 32% 20% 6%	330
	21st to end	Day	29% 17% 32% 16% 5%	363
November	1st to 10th	Day	19% 18% 35% 19% 7% 2	330
	11th to 20th	Day	27% 20% 32% 14% 6% 1	330
	21st to end	Day	27% 14% 37% 19% 4	330
December	1st to 10th	Day	16% 23% 39% 14% 7%	330
	11th to 20th	Day	22% 20% 35% 18% 4 1	330
	21st to end	Day	28% 22% 36% 12% 2	363
January	1st to 10th	Night	18% 15% 41% 22% 4	1050
	11th to 20th	Night	21% 18% 36% 20% 4 1	1050
	21st to end	Night	21% 14% 38% 25% 3	1155
February	1st to 10th	Night	22% 15% 35% 23% 4	1022
	11th to 20th	Night	20% 15% 36% 24% 4	823
	21st to end	Night	21% 15% 40% 20% 3	692
March	1st to 10th	Night	21% 16% 35% 22% 5%	809
	11th to 20th	Night	17% 12% 38% 26% 7%	762
	21st to end	Night	23% 13% 32% 25% 6% 1	660
April	1st to 10th	Night	20% 15% 34% 25% 6%	600
	11th to 20th	Night	22% 14% 32% 25% 6%	593
	21st to end	Night	19% 12% 34% 27% 7%	600
May	1st to 10th	Night	18% 9% 35% 31% 7% 1	600
	11th to 20th	Night	17% 8% 30% 31% 13%	591
	21st to end	Night	13% 7% 28% 36% 17%	650
June	1st to 10th	Night	10% 6% 28% 40% 15% 1	600
	11th to 20th	Night	10% 5% 31% 44% 10% 1	600
	21st to end	Night	10% 5% 31% 36% 17% 1	600
July	1st to 10th	Night	8% 3 17% 44% 25% 3	585
	11th to 20th	Night	8% 3 20% 41% 26% 2	582
	21st to end	Night	6% 2 20% 45% 25% 2	657
August	1st to 10th	Night	4 4 15% 45% 29% 3	597
	11th to 20th	Night	7% 2 14% 42% 30% 4	594
	21st to end	Night	8% 2 18% 41% 28% 2	660
September	1st to 10th	Night	11% 4 20% 36% 26% 3	600
	11th to 20th	Night	9% 4 19% 36% 28% 4	695
	21st to end	Night	11% 8% 23% 34% 21% 2	800
October	1st to 10th	Night	12% 6% 27% 36% 17% 2	800
	11th to 20th	Night	20% 13% 30% 27% 10%	800
	21st to end	Night	24% 14% 31% 22% 9%	880
November	1st to 10th	Night	18% 11% 38% 24% 9% 1	820
	11th to 20th	Night	21% 17% 32% 24% 5%	840
	21st to end	Night	21% 15% 36% 22% 6%	924
December	1st to 10th	Night	21% 16% 36% 23% 5%	1050
	11th to 20th	Night	23% 14% 33% 25% 4	1050
	21st to end	Night	31% 14% 32% 21% 2	1155

Page generated at 2026-02-28 00:40:22. Version ac07

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