England/Idlewild Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the England/Idlewild 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	14% 9% 3 7% 5% 4 4 4 5% 7% 37%	101297
	Night	14% 10% 3 7% 4 4 4 4 5% 7% 38%	97723
Transparency	Day	45% 3 10% 24% 16% 2	104979
	Night	45% 3 10% 24% 16% 2	102180
Seeing	Day	18% 8% 25% 25% 16% 8%	15344
	Night	20% 7% 24% 31% 17% 2	25046

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	15% 18% 6% 9% 4 4 4 3 4 6% 27%	2527
	11th to 20th	Day	17% 13% 6% 12% 5% 6% 5% 3 4 4 25%	2717
	21st to end	Day	28% 15% 8% 7% 5% 3 3 2 3 4 20%	3124
February	1st to 10th	Day	18% 14% 5% 8% 4 4 3 3 5% 5% 31%	1833
	11th to 20th	Day	15% 12% 4 10% 5% 4 4 2 5% 5% 32%	1848
	21st to end	Day	19% 14% 5% 9% 4 3 4 3 4 5% 31%	1570
March	1st to 10th	Day	24% 15% 4 8% 4 3 3 3 4 5% 28%	3120
	11th to 20th	Day	14% 8% 3 6% 4 4 4 3 5% 7% 42%	3479
	21st to end	Day	16% 11% 3 6% 5% 4 4 4 5% 6% 35%	3815
April	1st to 10th	Day	15% 9% 3 7% 4 4 4 4 5% 8% 35%	2261
	11th to 20th	Day	16% 8% 3 7% 4 4 4 4 4 7% 39%	2286
	21st to end	Day	18% 8% 2 7% 5% 4 4 4 5% 7% 35%	2470
May	1st to 10th	Day	21% 10% 3 7% 5% 4 5% 4 5% 7% 29%	4082
	11th to 20th	Day	20% 9% 2 6% 3 4 4 3 5% 7% 37%	4081
	21st to end	Day	9% 6% 3 8% 6% 6% 7% 5% 8% 9% 33%	4476
June	1st to 10th	Day	12% 6% 2 6% 5% 4 5% 5% 6% 8% 41%	2485
	11th to 20th	Day	9% 5% 2 6% 5% 5% 5% 5% 6% 9% 44%	2660
	21st to end	Day	8% 6% 2 7% 5% 5% 6% 5% 5% 10% 40%	2660
July	1st to 10th	Day	12% 7% 2 6% 5% 5% 5% 4 6% 10% 38%	4440
	11th to 20th	Day	7% 5% 2 5% 4 5% 5% 4 7% 11% 46%	4317
	21st to end	Day	11% 7% 3 9% 7% 7% 6% 6% 7% 9% 30%	4466
August	1st to 10th	Day	8% 5% 2 6% 5% 4 5% 4 7% 10% 44%	4104
	11th to 20th	Day	8% 6% 2 6% 4 5% 5% 5% 7% 11% 41%	4022
	21st to end	Day	6% 4 2 5% 4 4 4 4 5% 9% 54%	4180
September	1st to 10th	Day	13% 5% 2 6% 3 4 4 4 5% 7% 47%	2176
	11th to 20th	Day	8% 5% 2 6% 4 3 4 5% 6% 9% 47%	2090
	21st to end	Day	15% 7% 2 6% 4 3 4 3 5% 5% 48%	2090
October	1st to 10th	Day	10% 5% 2 6% 5% 5% 5% 3 5% 5% 51%	2090
	11th to 20th	Day	12% 7% 2 6% 5% 3 3 3 6% 7% 46%	1948
	21st to end	Day	18% 8% 3 7% 3 4 3 3 5% 6% 39%	1929
November	1st to 10th	Day	9% 7% 3 5% 4 3 4 2 3 6% 54%	1708
	11th to 20th	Day	14% 10% 4 7% 4 3 4 3 6% 7% 38%	1710
	21st to end	Day	17% 10% 3 8% 4 3 3 3 4 6% 38%	1710
December	1st to 10th	Day	21% 15% 4 8% 6% 4 4 3 4 4 28%	1710
	11th to 20th	Day	15% 15% 5% 9% 6% 4 4 3 5% 5% 30%	2153
	21st to end	Day	21% 20% 5% 8% 6% 4 4 3 4 6% 19%	2960
January	1st to 10th	Night	16% 17% 6% 11% 5% 4 5% 4 4 5% 23%	4428
	11th to 20th	Night	14% 17% 6% 16% 6% 5% 4 3 3 4 23%	4240
	21st to end	Night	25% 18% 5% 8% 4 3 3 2 3 4 24%	4532
February	1st to 10th	Night	20% 13% 4 9% 5% 4 5% 3 4 5% 28%	2342
	11th to 20th	Night	17% 11% 3 9% 5% 4 3 3 5% 6% 32%	2218
	21st to end	Night	21% 14% 4 8% 4 3 3 3 4 6% 30%	1884
March	1st to 10th	Night	22% 14% 2 6% 4 4 3 3 5% 5% 32%	3733
	11th to 20th	Night	13% 7% 2 6% 3 4 4 4 5% 6% 45%	3480
	21st to end	Night	16% 9% 2 8% 5% 3 4 3 5% 6% 39%	3817
April	1st to 10th	Night	13% 9% 3 6% 5% 4 4 4 6% 8% 37%	1933
	11th to 20th	Night	14% 8% 3 6% 5% 4 3 4 6% 7% 40%	1840
	21st to end	Night	17% 7% 3 6% 4 4 4 4 6% 7% 37%	1710
May	1st to 10th	Night	20% 12% 4 8% 5% 4 4 4 5% 7% 27%	2813
	11th to 20th	Night	19% 6% 2 5% 4 5% 4 4 6% 8% 38%	2812
	21st to end	Night	8% 6% 3 5% 4 4 5% 5% 6% 10% 45%	3079
June	1st to 10th	Night	8% 6% 2 5% 4 4 4 4 6% 10% 47%	1689
	11th to 20th	Night	7% 6% 2 5% 4 4 4 4 6% 12% 47%	1520
	21st to end	Night	6% 4 2 5% 5% 4 5% 5% 7% 10% 47%	1520
July	1st to 10th	Night	10% 6% 2 6% 4 4 4 3 5% 9% 47%	2530
	11th to 20th	Night	5% 4 2 5% 4 5% 4 4 7% 9% 52%	2645
	21st to end	Night	10% 7% 3 7% 6% 6% 5% 5% 7% 10% 36%	3087
August	1st to 10th	Night	7% 5% 2 7% 4 4 5% 4 7% 10% 45%	2825
	11th to 20th	Night	7% 6% 2 7% 4 5% 4 4 7% 9% 46%	2804
	21st to end	Night	3 3 1 4 3 4 4 4 6% 10% 59%	3476
September	1st to 10th	Night	12% 5% 1 4 3 3 4 4 5% 7% 51%	1985
	11th to 20th	Night	8% 4 2 5% 3 3 4 4 5% 8% 53%	2090
	21st to end	Night	15% 6% 2 5% 4 3 4 2 4 6% 49%	2090
October	1st to 10th	Night	8% 5% 2 5% 4 3 3 3 5% 6% 56%	2090
	11th to 20th	Night	14% 6% 3 6% 3 4 4 3 5% 6% 46%	2232
	21st to end	Night	17% 9% 2 6% 3 4 3 3 5% 6% 41%	2665
November	1st to 10th	Night	12% 7% 2 6% 4 3 4 3 5% 5% 48%	2470
	11th to 20th	Night	15% 8% 3 8% 4 4 4 3 5% 7% 40%	2470
	21st to end	Night	19% 11% 3 6% 5% 4 4 3 4 6% 35%	2470
December	1st to 10th	Night	20% 12% 5% 8% 5% 4 4 3 5% 6% 29%	2470
	11th to 20th	Night	18% 13% 5% 9% 5% 3 3 3 5% 6% 31%	3042
	21st to end	Night	19% 19% 7% 11% 5% 5% 4 3 4 5% 18%	4692

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% 1 10% 17% 11%	2528
	11th to 20th	Day	64% 2 7% 18% 8%	2717
	21st to end	Day	70% 1 7% 18% 4 1	3124
February	1st to 10th	Day	56% 2 8% 20% 12% 2	1833
	11th to 20th	Day	54% 3 8% 22% 12% 1	1858
	21st to end	Day	56% 2 9% 22% 10% 2	1570
March	1st to 10th	Day	60% 2 7% 20% 9% 3	3120
	11th to 20th	Day	43% 2 9% 27% 17% 2	3479
	21st to end	Day	50% 2 11% 24% 12% 1	3815
April	1st to 10th	Day	47% 4 10% 24% 14% 2	2261
	11th to 20th	Day	46% 2 8% 24% 17% 3	2286
	21st to end	Day	48% 2 10% 24% 12% 2	2470
May	1st to 10th	Day	55% 3 11% 22% 8% 1	4120
	11th to 20th	Day	48% 2 13% 24% 13% 1	4085
	21st to end	Day	45% 4 12% 21% 16% 2	4489
June	1st to 10th	Day	40% 4 11% 26% 17% 2	2485
	11th to 20th	Day	36% 5% 13% 25% 20% 2	2660
	21st to end	Day	40% 5% 13% 23% 15% 5%	2660
July	1st to 10th	Day	42% 4 12% 22% 19% 2	4371
	11th to 20th	Day	30% 5% 12% 33% 18% 1	4242
	21st to end	Day	49% 6% 12% 18% 13% 2	4324
August	1st to 10th	Day	33% 5% 15% 33% 13% 1	4091
	11th to 20th	Day	35% 5% 11% 33% 15% 1	4061
	21st to end	Day	28% 4 14% 30% 20% 4	4179
September	1st to 10th	Day	38% 3 9% 24% 20% 6%	2176
	11th to 20th	Day	34% 4 11% 27% 22% 3	2090
	21st to end	Day	39% 3 9% 26% 21% 2	2090
October	1st to 10th	Day	24% 3 7% 32% 33% 2	3480
	11th to 20th	Day	30% 3 7% 30% 28% 2	3214
	21st to end	Day	36% 2 10% 26% 24% 2	3153
November	1st to 10th	Day	34% 3 8% 30% 22% 3	1708
	11th to 20th	Day	46% 3 6% 24% 17% 4	1710
	21st to end	Day	49% 2 9% 24% 15% 1	1710
December	1st to 10th	Day	62% 2 9% 19% 8% 1	1710
	11th to 20th	Day	58% 2 6% 21% 13% 1	2150
	21st to end	Day	69% 2 8% 13% 8% 1	2960
January	1st to 10th	Night	64% 2 8% 16% 10%	4428
	11th to 20th	Night	68% 1 8% 15% 8%	4240
	21st to end	Night	66% 1 6% 18% 7% 1	4532
February	1st to 10th	Night	60% 2 9% 20% 8% 1	2342
	11th to 20th	Night	53% 2 8% 22% 12% 1	2219
	21st to end	Night	57% 2 10% 18% 10% 3	1884
March	1st to 10th	Night	56% 2 5% 24% 11% 1	3733
	11th to 20th	Night	40% 3 11% 27% 18% 1	3480
	21st to end	Night	48% 2 8% 29% 12% 1	3817
April	1st to 10th	Night	45% 3 9% 27% 13% 2	1933
	11th to 20th	Night	43% 2 10% 20% 19% 6%	1840
	21st to end	Night	46% 3 11% 24% 13% 3	1710
May	1st to 10th	Night	58% 3 10% 20% 7% 2	2840
	11th to 20th	Night	45% 3 14% 27% 9% 1	2813
	21st to end	Night	35% 4 13% 29% 15% 4	3087
June	1st to 10th	Night	33% 4 12% 27% 21% 3	1689
	11th to 20th	Night	31% 5% 14% 24% 22% 4	1520
	21st to end	Night	30% 6% 17% 24% 18% 6%	1520
July	1st to 10th	Night	35% 5% 10% 25% 18% 6%	2490
	11th to 20th	Night	27% 6% 13% 32% 20% 2	2597
	21st to end	Night	42% 5% 13% 23% 13% 4	2988
August	1st to 10th	Night	32% 6% 14% 34% 12% 1	2814
	11th to 20th	Night	34% 6% 10% 31% 18% 1	2831
	21st to end	Night	21% 4 15% 34% 22% 3	3476
September	1st to 10th	Night	32% 4 11% 26% 20% 7%	1985
	11th to 20th	Night	29% 4 9% 28% 26% 4	2090
	21st to end	Night	39% 2 7% 24% 24% 3	2090
October	1st to 10th	Night	22% 2 6% 26% 42% 2	3480
	11th to 20th	Night	27% 2 8% 27% 34% 2	3705
	21st to end	Night	33% 3 7% 23% 29% 5%	4391
November	1st to 10th	Night	37% 3 9% 23% 24% 4	2470
	11th to 20th	Night	45% 2 8% 22% 19% 4	2470
	21st to end	Night	52% 2 9% 21% 14% 1	2470
December	1st to 10th	Night	57% 2 10% 20% 10% 1	2470
	11th to 20th	Night	55% 2 8% 22% 12% 1	3044
	21st to end	Night	70% 2 8% 14% 6%	4692

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	24% 14% 36% 20% 6%	270
	11th to 20th	Day	29% 19% 33% 14% 4	270
	21st to end	Day	31% 17% 32% 18% 2	297
February	1st to 10th	Day	29% 14% 37% 16% 3	270
	11th to 20th	Day	27% 21% 37% 10% 4 1	270
	21st to end	Day	32% 14% 42% 9% 4	225
March	1st to 10th	Day	24% 18% 39% 16% 3	270
	11th to 20th	Day	26% 13% 36% 18% 6% 1	459
	21st to end	Day	30% 13% 31% 19% 7% 1	506
April	1st to 10th	Day	23% 14% 27% 22% 11% 2	460
	11th to 20th	Day	21% 15% 27% 23% 9% 5%	452
	21st to end	Day	23% 11% 33% 20% 8% 4	460
May	1st to 10th	Day	24% 8% 31% 22% 10% 4	463
	11th to 20th	Day	23% 5% 22% 28% 16% 7%	487
	21st to end	Day	14% 4 24% 26% 21% 11%	529
June	1st to 10th	Day	15% 4 19% 30% 23% 10%	505
	11th to 20th	Day	10% 3 20% 36% 22% 9%	680
	21st to end	Day	11% 3 24% 32% 20% 11%	680
July	1st to 10th	Day	15% 2 13% 26% 24% 20%	671
	11th to 20th	Day	10% 2 20% 31% 24% 14%	597
	21st to end	Day	13% 2 12% 32% 25% 15%	532
August	1st to 10th	Day	12% 2 11% 27% 29% 20%	486
	11th to 20th	Day	13% 2 14% 33% 23% 14%	479
	21st to end	Day	10% 2 12% 26% 33% 17%	539
September	1st to 10th	Day	14% 3 12% 28% 30% 13%	490
	11th to 20th	Day	10% 2 15% 26% 30% 18%	490
	21st to end	Day	19% 5% 19% 24% 23% 9%	490
October	1st to 10th	Day	10% 3 20% 36% 22% 8%	490
	11th to 20th	Day	16% 12% 28% 25% 15% 4	490
	21st to end	Day	24% 6% 37% 22% 10% 1	378
November	1st to 10th	Day	13% 10% 33% 29% 10% 4	282
	11th to 20th	Day	21% 14% 33% 20% 9% 2	270
	21st to end	Day	24% 9% 34% 23% 9%	270
December	1st to 10th	Day	21% 17% 35% 18% 8% 1	270
	11th to 20th	Day	19% 14% 41% 17% 8% 1	270
	21st to end	Day	31% 13% 32% 18% 4 1	297
January	1st to 10th	Night	22% 14% 31% 27% 5%	950
	11th to 20th	Night	31% 12% 32% 20% 4	828
	21st to end	Night	27% 11% 34% 24% 4	836
February	1st to 10th	Night	28% 11% 32% 27% 3	760
	11th to 20th	Night	26% 14% 34% 24% 3	743
	21st to end	Night	29% 11% 35% 24% 2	628
March	1st to 10th	Night	25% 11% 28% 29% 5%	760
	11th to 20th	Night	24% 11% 32% 24% 8% 1	760
	21st to end	Night	23% 9% 31% 30% 7%	836
April	1st to 10th	Night	19% 9% 32% 31% 9%	603
	11th to 20th	Night	21% 9% 26% 32% 11% 1	563
	21st to end	Night	20% 5% 34% 31% 9% 1	570
May	1st to 10th	Night	21% 4 30% 30% 14% 1	570
	11th to 20th	Night	20% 2 20% 36% 19% 3	561
	21st to end	Night	10% 2 18% 38% 27% 5%	617
June	1st to 10th	Night	11% 1 18% 43% 24% 2	570
	11th to 20th	Night	11% 2 14% 39% 31% 4	570
	21st to end	Night	7% 1 18% 41% 28% 4	570
July	1st to 10th	Night	13% 2 10% 32% 34% 10%	555
	11th to 20th	Night	9% 1 9% 38% 39% 5%	552
	21st to end	Night	13% 1 8% 39% 34% 4	624
August	1st to 10th	Night	10% 1 6% 37% 41% 5%	567
	11th to 20th	Night	10% 1 9% 41% 34% 5%	564
	21st to end	Night	7% 1 6% 35% 42% 9%	627
September	1st to 10th	Night	15% 2 10% 33% 34% 6%	655
	11th to 20th	Night	11% 2 11% 31% 40% 6%	760
	21st to end	Night	18% 3 18% 33% 24% 3	760
October	1st to 10th	Night	11% 3 20% 36% 25% 5%	760
	11th to 20th	Night	18% 7% 22% 35% 16% 2	760
	21st to end	Night	23% 6% 29% 29% 12% 1	836
November	1st to 10th	Night	17% 6% 26% 32% 17% 1	760
	11th to 20th	Night	22% 11% 28% 28% 11% 1	760
	21st to end	Night	26% 9% 27% 29% 9% 1	760
December	1st to 10th	Night	28% 8% 33% 25% 6%	760
	11th to 20th	Night	26% 9% 31% 26% 8% 1	760
	21st to end	Night	30% 10% 30% 26% 4	931

Page generated at 2024-11-03 02:11:10. Version ac07

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