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 2024-12-02.

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% 3 8% 5% 4 5% 4 6% 7% 36%	101563
	Night	14% 10% 4 7% 4 4 4 3 5% 6% 38%	98152
Transparency	Day	44% 6% 11% 23% 14% 2	105129
	Night	44% 6% 11% 23% 15% 2	102727
Seeing	Day	17% 12% 29% 25% 12% 4	15898
	Night	17% 11% 31% 29% 11% 1	25764

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	14% 13% 8% 12% 6% 5% 4 3 4 5% 27%	2527
	11th to 20th	Day	13% 14% 6% 15% 5% 5% 4 7% 7% 3 20%	2530
	21st to end	Day	18% 22% 7% 12% 5% 3 4 3 4 5% 17%	2886
February	1st to 10th	Day	15% 14% 5% 8% 6% 6% 5% 4 4 6% 27%	1733
	11th to 20th	Day	14% 11% 5% 8% 6% 4 4 3 4 6% 34%	1848
	21st to end	Day	14% 14% 5% 10% 5% 3 4 3 5% 6% 30%	1570
March	1st to 10th	Day	14% 13% 4 8% 5% 4 4 3 4 6% 34%	3120
	11th to 20th	Day	10% 7% 3 8% 5% 5% 4 3 6% 7% 40%	3276
	21st to end	Day	19% 13% 5% 14% 6% 5% 5% 4 5% 6% 19%	4165
April	1st to 10th	Day	17% 13% 4 8% 5% 4 4 4 5% 6% 31%	2280
	11th to 20th	Day	16% 11% 3 6% 5% 5% 4 4 5% 5% 36%	2254
	21st to end	Day	20% 9% 3 7% 5% 6% 4 3 5% 6% 33%	2367
May	1st to 10th	Day	16% 7% 2 6% 5% 5% 5% 4 6% 8% 35%	4082
	11th to 20th	Day	15% 7% 2 6% 4 5% 4 3 5% 7% 41%	4329
	21st to end	Day	11% 7% 2 6% 4 5% 5% 4 8% 9% 41%	4824
June	1st to 10th	Day	9% 6% 3 5% 5% 5% 4 4 6% 8% 45%	2660
	11th to 20th	Day	9% 6% 2 6% 5% 4 5% 4 6% 8% 45%	2660
	21st to end	Day	11% 7% 2 6% 5% 5% 5% 5% 7% 9% 37%	2660
July	1st to 10th	Day	11% 8% 3 8% 5% 6% 6% 5% 7% 9% 32%	4440
	11th to 20th	Day	7% 4 2 5% 4 4 5% 5% 7% 11% 47%	4440
	21st to end	Day	8% 6% 3 7% 6% 5% 5% 4 7% 8% 40%	4813
August	1st to 10th	Day	8% 6% 2 7% 4 4 5% 5% 7% 9% 43%	4339
	11th to 20th	Day	10% 5% 2 6% 4 4 5% 5% 7% 10% 42%	3729
	21st to end	Day	7% 5% 2 6% 4 4 5% 4 7% 9% 47%	4180
September	1st to 10th	Day	11% 6% 2 6% 4 4 5% 4 6% 8% 46%	2280
	11th to 20th	Day	11% 5% 1 4 3 4 4 3 5% 7% 53%	2171
	21st to end	Day	9% 8% 3 6% 5% 3 4 4 6% 8% 45%	2090
October	1st to 10th	Day	11% 7% 2 6% 5% 3 3 3 6% 7% 47%	2022
	11th to 20th	Day	17% 9% 3 7% 5% 5% 3 4 5% 8% 36%	1900
	21st to end	Day	19% 9% 3 7% 4 4 3 3 4 6% 37%	1882
November	1st to 10th	Day	11% 10% 3 7% 4 3 4 4 5% 6% 44%	1762
	11th to 20th	Day	15% 13% 4 8% 5% 3 4 3 5% 7% 33%	1800
	21st to end	Day	17% 11% 4 9% 5% 4 4 3 5% 4 34%	1715
December	1st to 10th	Day	14% 12% 4 10% 6% 4 5% 4 3 5% 32%	1528
	11th to 20th	Day	13% 14% 4 10% 6% 4 5% 4 5% 7% 29%	1918
	21st to end	Day	21% 22% 9% 13% 6% 4 3 2 3 3 14%	2783
January	1st to 10th	Night	14% 14% 7% 12% 5% 4 3 3 4 4 29%	4428
	11th to 20th	Night	15% 18% 7% 13% 6% 3 4 5% 6% 4 20%	4440
	21st to end	Night	21% 18% 8% 10% 5% 4 4 3 4 4 21%	4779
February	1st to 10th	Night	15% 15% 4 8% 6% 4 4 3 3 6% 32%	2446
	11th to 20th	Night	13% 12% 3 8% 4 4 4 3 4 6% 38%	2218
	21st to end	Night	17% 12% 4 9% 3 4 3 3 5% 5% 35%	1884
March	1st to 10th	Night	18% 10% 3 6% 4 4 3 2 5% 5% 41%	3733
	11th to 20th	Night	10% 7% 2 7% 4 4 4 3 5% 6% 47%	3712
	21st to end	Night	21% 11% 5% 10% 5% 4 4 3 4 5% 27%	3466
April	1st to 10th	Night	16% 9% 2 7% 4 4 4 3 5% 6% 40%	1900
	11th to 20th	Night	18% 9% 3 6% 5% 3 4 3 5% 5% 39%	1875
	21st to end	Night	17% 9% 3 7% 4 4 4 3 6% 7% 36%	1811
May	1st to 10th	Night	15% 8% 3 7% 5% 4 5% 5% 5% 8% 35%	2813
	11th to 20th	Night	14% 6% 2 5% 3 4 5% 4 7% 9% 40%	2570
	21st to end	Night	11% 7% 3 6% 5% 4 4 3 5% 8% 44%	2743
June	1st to 10th	Night	9% 5% 2 5% 4 4 4 4 6% 9% 48%	1520
	11th to 20th	Night	7% 6% 2 6% 3 5% 4 4 8% 8% 47%	1520
	21st to end	Night	10% 6% 2 5% 5% 5% 5% 5% 7% 7% 42%	1520
July	1st to 10th	Night	12% 6% 3 8% 5% 5% 5% 4 6% 8% 39%	2530
	11th to 20th	Night	6% 4 2 6% 4 4 4 4 6% 9% 53%	2530
	21st to end	Night	5% 5% 2 6% 6% 5% 6% 5% 8% 8% 45%	2750
August	1st to 10th	Night	5% 5% 2 6% 5% 5% 4 4 7% 9% 48%	2592
	11th to 20th	Night	8% 5% 2 6% 3 4 4 4 7% 8% 50%	3100
	21st to end	Night	8% 4 2 5% 3 4 4 3 5% 8% 53%	3476
September	1st to 10th	Night	10% 6% 2 5% 3 3 3 3 4 7% 55%	1900
	11th to 20th	Night	9% 4 2 5% 3 4 3 3 6% 8% 54%	1990
	21st to end	Night	9% 7% 2 6% 5% 4 4 3 6% 8% 46%	2090
October	1st to 10th	Night	11% 5% 2 5% 4 3 4 4 5% 6% 52%	2156
	11th to 20th	Night	18% 6% 3 5% 5% 3 3 3 3 6% 46%	2280
	21st to end	Night	20% 9% 2 6% 4 3 4 3 4 7% 37%	2714
November	1st to 10th	Night	12% 8% 3 5% 4 3 3 3 4 6% 48%	2536
	11th to 20th	Night	15% 11% 4 7% 5% 3 5% 3 5% 6% 37%	2600
	21st to end	Night	16% 10% 4 8% 5% 4 3 3 5% 5% 36%	2680
December	1st to 10th	Night	16% 12% 3 9% 5% 5% 4 3 5% 6% 32%	2687
	11th to 20th	Night	16% 13% 4 9% 5% 4 4 3 4 6% 32%	3279
	21st to end	Night	23% 18% 6% 10% 5% 5% 4 4 4 5% 16%	4884

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	60% 5% 11% 17% 7%	2528
	11th to 20th	Day	61% 7% 10% 13% 9%	2530
	21st to end	Day	69% 5% 8% 12% 6%	2886
February	1st to 10th	Day	58% 6% 11% 14% 10% 2	1733
	11th to 20th	Day	50% 5% 10% 23% 10% 2	1858
	21st to end	Day	55% 5% 11% 19% 8% 2	1570
March	1st to 10th	Day	50% 7% 10% 20% 11% 2	3120
	11th to 20th	Day	41% 6% 11% 30% 11% 1	3276
	21st to end	Day	65% 7% 12% 13% 3	4165
April	1st to 10th	Day	54% 5% 10% 20% 11%	2280
	11th to 20th	Day	48% 6% 9% 21% 12% 3	2254
	21st to end	Day	51% 6% 11% 17% 12% 2	2367
May	1st to 10th	Day	45% 8% 10% 25% 12%	4120
	11th to 20th	Day	41% 7% 10% 28% 15%	4333
	21st to end	Day	36% 8% 12% 22% 18% 5%	4837
June	1st to 10th	Day	35% 7% 12% 27% 17% 2	2660
	11th to 20th	Day	35% 8% 10% 24% 20% 3	2660
	21st to end	Day	40% 9% 13% 23% 13% 2	2660
July	1st to 10th	Day	45% 7% 13% 22% 11% 2	4371
	11th to 20th	Day	29% 7% 17% 29% 17% 1	4365
	21st to end	Day	40% 8% 15% 16% 19% 3	4662
August	1st to 10th	Day	35% 7% 16% 29% 13% 1	4324
	11th to 20th	Day	35% 7% 12% 31% 15% 1	3765
	21st to end	Day	32% 6% 13% 28% 19% 2	4179
September	1st to 10th	Day	36% 6% 12% 24% 18% 4	2280
	11th to 20th	Day	30% 6% 11% 28% 23% 3	2171
	21st to end	Day	37% 7% 8% 27% 20% 2	2090
October	1st to 10th	Day	25% 4 7% 30% 32% 2	3360
	11th to 20th	Day	32% 4 11% 27% 25% 1	3140
	21st to end	Day	43% 4 9% 28% 14% 4	3082
November	1st to 10th	Day	41% 5% 13% 24% 15% 2	1762
	11th to 20th	Day	52% 5% 11% 22% 10% 1	1800
	21st to end	Day	54% 4 11% 23% 8%	1715
December	1st to 10th	Day	55% 5% 12% 19% 8% 1	1528
	11th to 20th	Day	54% 5% 15% 17% 7% 2	1915
	21st to end	Day	77% 4 7% 9% 4	2783
January	1st to 10th	Night	56% 6% 10% 18% 9% 1	4428
	11th to 20th	Night	65% 5% 10% 12% 8%	4440
	21st to end	Night	67% 5% 8% 14% 6% 1	4779
February	1st to 10th	Night	55% 4 10% 17% 12% 1	2446
	11th to 20th	Night	47% 6% 10% 22% 14% 1	2219
	21st to end	Night	51% 5% 11% 19% 11% 4	1884
March	1st to 10th	Night	46% 6% 12% 23% 10% 4	3733
	11th to 20th	Night	37% 6% 10% 27% 18% 2	3712
	21st to end	Night	58% 6% 9% 19% 6% 1	3466
April	1st to 10th	Night	44% 6% 12% 23% 13% 2	1900
	11th to 20th	Night	46% 5% 7% 21% 16% 4	1875
	21st to end	Night	46% 7% 11% 21% 12% 3	1811
May	1st to 10th	Night	45% 7% 11% 21% 13% 2	2840
	11th to 20th	Night	36% 10% 15% 27% 11% 1	2571
	21st to end	Night	36% 8% 10% 21% 20% 5%	2751
June	1st to 10th	Night	33% 7% 13% 25% 19% 3	1520
	11th to 20th	Night	32% 7% 10% 27% 22% 3	1520
	21st to end	Night	37% 9% 14% 20% 17% 2	1520
July	1st to 10th	Night	43% 6% 15% 19% 13% 4	2490
	11th to 20th	Night	27% 7% 13% 32% 19% 2	2482
	21st to end	Night	33% 8% 15% 18% 22% 4	2662
August	1st to 10th	Night	30% 8% 15% 28% 18% 1	2583
	11th to 20th	Night	30% 6% 14% 30% 19% 1	3130
	21st to end	Night	28% 6% 12% 33% 17% 4	3476
September	1st to 10th	Night	30% 6% 10% 27% 24% 3	1900
	11th to 20th	Night	28% 5% 9% 32% 25% 2	1990
	21st to end	Night	35% 7% 11% 30% 16% 2	2090
October	1st to 10th	Night	22% 4 7% 37% 28% 2	3598
	11th to 20th	Night	35% 4 7% 24% 28% 2	3779
	21st to end	Night	41% 4 8% 26% 18% 3	4464
November	1st to 10th	Night	38% 5% 8% 27% 18% 3	2536
	11th to 20th	Night	48% 5% 11% 21% 13% 2	2600
	21st to end	Night	50% 5% 11% 22% 12%	2680
December	1st to 10th	Night	53% 5% 11% 22% 8% 1	2687
	11th to 20th	Night	53% 5% 12% 19% 10% 1	3281
	21st to end	Night	70% 5% 9% 12% 4	4884

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	21% 16% 36% 21% 4 1	270
	11th to 20th	Day	21% 16% 41% 16% 4 1	270
	21st to end	Day	23% 21% 30% 21% 4 1	297
February	1st to 10th	Day	22% 21% 37% 16% 3	270
	11th to 20th	Day	25% 18% 34% 19% 3	270
	21st to end	Day	24% 20% 41% 12% 3	225
March	1st to 10th	Day	23% 26% 35% 16% 1	270
	11th to 20th	Day	29% 17% 34% 15% 4 1	282
	21st to end	Day	29% 15% 32% 18% 5% 2	506
April	1st to 10th	Day	25% 15% 33% 21% 6%	460
	11th to 20th	Day	21% 24% 24% 19% 10% 2	452
	21st to end	Day	23% 15% 30% 23% 8% 1	460
May	1st to 10th	Day	20% 14% 32% 24% 8% 2	463
	11th to 20th	Day	20% 12% 31% 24% 10% 3	631
	21st to end	Day	17% 10% 30% 23% 15% 5%	734
June	1st to 10th	Day	11% 9% 31% 29% 15% 5%	680
	11th to 20th	Day	11% 8% 34% 28% 15% 4	680
	21st to end	Day	12% 11% 30% 31% 13% 4	680
July	1st to 10th	Day	9% 4 23% 31% 20% 14%	671
	11th to 20th	Day	10% 7% 26% 32% 16% 9%	668
	21st to end	Day	7% 4 28% 35% 18% 7%	739
August	1st to 10th	Day	8% 4 21% 34% 22% 10%	640
	11th to 20th	Day	10% 6% 20% 28% 24% 11%	479
	21st to end	Day	7% 5% 18% 34% 25% 10%	539
September	1st to 10th	Day	13% 7% 22% 32% 21% 6%	490
	11th to 20th	Day	10% 4 19% 34% 24% 9%	490
	21st to end	Day	13% 14% 26% 24% 17% 7%	490
October	1st to 10th	Day	15% 10% 27% 28% 16% 4	422
	11th to 20th	Day	19% 24% 32% 19% 6%	300
	21st to end	Day	31% 18% 30% 15% 6%	330
November	1st to 10th	Day	19% 16% 36% 19% 7% 2	300
	11th to 20th	Day	25% 20% 34% 14% 5% 1	300
	21st to end	Day	25% 13% 38% 20% 3	300
December	1st to 10th	Day	17% 22% 40% 15% 6%	273
	11th to 20th	Day	19% 19% 37% 20% 5% 1	270
	21st to end	Day	25% 23% 38% 12% 2	297
January	1st to 10th	Night	19% 14% 41% 22% 4	950
	11th to 20th	Night	22% 16% 35% 21% 4 1	950
	21st to end	Night	20% 13% 36% 27% 4	1045
February	1st to 10th	Night	22% 15% 35% 24% 4	926
	11th to 20th	Night	20% 14% 36% 24% 5%	743
	21st to end	Night	23% 14% 39% 20% 4	628
March	1st to 10th	Night	21% 16% 35% 23% 6%	760
	11th to 20th	Night	17% 11% 38% 26% 7%	724
	21st to end	Night	23% 13% 32% 25% 6% 1	627
April	1st to 10th	Night	19% 15% 35% 25% 6%	570
	11th to 20th	Night	22% 14% 31% 26% 7%	563
	21st to end	Night	19% 12% 35% 26% 8%	570
May	1st to 10th	Night	18% 9% 35% 31% 7% 1	570
	11th to 20th	Night	17% 8% 30% 31% 13%	561
	21st to end	Night	13% 6% 28% 36% 18%	617
June	1st to 10th	Night	10% 6% 29% 39% 16% 1	570
	11th to 20th	Night	9% 5% 31% 44% 11% 1	570
	21st to end	Night	11% 5% 30% 36% 17% 1	570
July	1st to 10th	Night	8% 3 17% 43% 26% 3	555
	11th to 20th	Night	8% 3 19% 41% 26% 2	552
	21st to end	Night	5% 2 21% 46% 24% 2	624
August	1st to 10th	Night	4 4 15% 45% 29% 3	567
	11th to 20th	Night	7% 2 14% 42% 30% 4	564
	21st to end	Night	9% 2 18% 41% 29% 2	627
September	1st to 10th	Night	12% 4 19% 37% 25% 3	570
	11th to 20th	Night	9% 5% 20% 36% 27% 4	660
	21st to end	Night	11% 8% 24% 33% 21% 3	760
October	1st to 10th	Night	12% 7% 27% 35% 17% 3	760
	11th to 20th	Night	21% 13% 30% 26% 10%	760
	21st to end	Night	24% 14% 31% 22% 9%	836
November	1st to 10th	Night	17% 11% 38% 24% 9% 1	780
	11th to 20th	Night	21% 17% 32% 24% 6%	800
	21st to end	Night	20% 14% 37% 22% 6%	880
December	1st to 10th	Night	21% 15% 35% 23% 5%	960
	11th to 20th	Night	23% 13% 33% 27% 4	950
	21st to end	Night	29% 15% 33% 21% 2	1045

Page generated at 2024-11-29 09:43:10. Version ac07

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