Old Mill State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Old Mill State Park clear sky chart from 2005-11-06 to 2024-11-10.

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% 35%	101812
	Night	10% 10% 4 9% 6% 5% 5% 4 6% 7% 34%	97483
Transparency	Day	46% 7% 15% 24% 8%	105282
	Night	47% 6% 14% 23% 9% 1	102096
Seeing	Day	14% 9% 31% 29% 14% 3	16200
	Night	15% 7% 33% 33% 11% 1	26107

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	6% 12% 8% 16% 7% 7% 6% 5% 7% 6% 21%	2218
	11th to 20th	Day	4 9% 3 16% 13% 11% 12% 8% 7% 5% 11%	2284
	21st to end	Day	7% 17% 8% 20% 6% 6% 5% 4 5% 5% 17%	2799
February	1st to 10th	Day	8% 13% 6% 11% 7% 6% 7% 6% 7% 5% 23%	1710
	11th to 20th	Day	7% 11% 4 10% 10% 7% 9% 6% 7% 7% 23%	1664
	21st to end	Day	7% 10% 4 14% 9% 8% 7% 4 5% 8% 25%	1485
March	1st to 10th	Day	11% 12% 4 9% 10% 5% 5% 4 5% 6% 29%	3252
	11th to 20th	Day	8% 9% 4 13% 10% 5% 6% 5% 6% 8% 27%	3480
	21st to end	Day	13% 15% 6% 11% 5% 4 4 3 5% 5% 30%	3814
April	1st to 10th	Day	11% 13% 4 7% 5% 5% 5% 4 5% 7% 33%	2272
	11th to 20th	Day	16% 11% 5% 8% 5% 5% 4 4 5% 6% 32%	2442
	21st to end	Day	20% 9% 3 8% 5% 4 5% 3 5% 6% 33%	2470
May	1st to 10th	Day	19% 9% 3 7% 4 5% 4 4 6% 7% 34%	4198
	11th to 20th	Day	17% 8% 2 7% 5% 5% 4 4 6% 7% 34%	4443
	21st to end	Day	19% 10% 3 7% 4 4 4 4 5% 7% 34%	5173
June	1st to 10th	Day	14% 6% 3 6% 5% 4 5% 4 7% 8% 39%	2850
	11th to 20th	Day	15% 6% 2 6% 4 4 5% 4 7% 8% 39%	2850
	21st to end	Day	12% 6% 3 7% 6% 5% 5% 5% 7% 8% 37%	2850
July	1st to 10th	Day	8% 4 1 5% 5% 5% 5% 5% 8% 12% 44%	4750
	11th to 20th	Day	7% 4 1 5% 3 4 5% 4 6% 9% 51%	4750
	21st to end	Day	6% 4 2 5% 4 4 5% 5% 7% 10% 49%	5031
August	1st to 10th	Day	10% 5% 2 5% 4 4 5% 4 6% 8% 48%	4117
	11th to 20th	Day	12% 5% 2 5% 3 4 4 4 6% 8% 46%	4041
	21st to end	Day	12% 5% 2 5% 4 3 4 3 5% 7% 50%	4532
September	1st to 10th	Day	12% 5% 3 5% 3 3 3 4 4 8% 50%	2336
	11th to 20th	Day	14% 5% 2 6% 4 4 5% 4 6% 8% 43%	2090
	21st to end	Day	14% 6% 2 5% 3 4 4 3 6% 8% 44%	2090
October	1st to 10th	Day	17% 10% 3 7% 4 4 4 3 4 6% 39%	1924
	11th to 20th	Day	13% 12% 3 8% 4 5% 4 3 5% 6% 36%	1900
	21st to end	Day	14% 15% 5% 9% 5% 3 5% 4 5% 5% 29%	1905
November	1st to 10th	Day	12% 16% 5% 9% 6% 5% 4 3 4 5% 31%	1604
	11th to 20th	Day	11% 14% 8% 15% 6% 4 4 3 5% 4 26%	1520
	21st to end	Day	10% 16% 4 11% 9% 6% 5% 4 5% 4 25%	1517
December	1st to 10th	Day	9% 14% 4 14% 9% 7% 6% 6% 6% 6% 18%	1330
	11th to 20th	Day	9% 15% 7% 14% 8% 6% 6% 5% 5% 5% 20%	1679
	21st to end	Day	14% 14% 5% 14% 8% 9% 7% 4 4 4 17%	2442
January	1st to 10th	Night	5% 11% 5% 16% 8% 9% 7% 5% 7% 6% 19%	4737
	11th to 20th	Night	5% 12% 6% 14% 13% 11% 9% 5% 6% 6% 13%	4683
	21st to end	Night	8% 16% 8% 15% 6% 5% 6% 5% 5% 5% 20%	4866
February	1st to 10th	Night	8% 11% 5% 11% 7% 6% 8% 5% 6% 7% 26%	2470
	11th to 20th	Night	7% 10% 4 10% 6% 6% 7% 4 7% 9% 31%	2403
	21st to end	Night	6% 12% 4 12% 9% 6% 5% 4 5% 7% 31%	1984
March	1st to 10th	Night	8% 11% 5% 10% 8% 5% 5% 4 5% 6% 33%	3581
	11th to 20th	Night	7% 10% 4 9% 9% 5% 5% 4 6% 7% 34%	3479
	21st to end	Night	13% 15% 6% 12% 5% 4 3 3 4 5% 30%	3817
April	1st to 10th	Night	11% 10% 3 7% 4 5% 4 4 6% 7% 39%	1905
	11th to 20th	Night	14% 12% 4 9% 5% 4 4 3 6% 5% 36%	1689
	21st to end	Night	18% 8% 3 8% 4 4 4 4 3 6% 38%	1710
May	1st to 10th	Night	18% 8% 2 6% 5% 4 4 4 6% 7% 36%	2750
	11th to 20th	Night	15% 7% 2 6% 4 5% 4 4 5% 7% 40%	2459
	21st to end	Night	17% 9% 2 5% 4 3 3 3 4 6% 44%	2414
June	1st to 10th	Night	12% 4 1 5% 5% 3 6% 4 8% 8% 45%	1330
	11th to 20th	Night	12% 5% 2 4 4 5% 5% 4 7% 8% 45%	1330
	21st to end	Night	9% 5% 2 5% 4 4 5% 4 7% 9% 46%	1330
July	1st to 10th	Night	8% 2 1 4 4 4 4 4 6% 10% 53%	2220
	11th to 20th	Night	4 3 1 4 4 3 4 3 6% 8% 61%	2220
	21st to end	Night	6% 3 2 5% 3 4 5% 4 8% 11% 49%	2531
August	1st to 10th	Night	5% 4 2 6% 4 4 4 5% 6% 9% 53%	2822
	11th to 20th	Night	11% 4 1 4 3 3 4 4 7% 9% 50%	2798
	21st to end	Night	10% 5% 2 6% 3 3 4 3 5% 7% 52%	3135
September	1st to 10th	Night	10% 4 2 5% 3 3 4 3 5% 7% 56%	1839
	11th to 20th	Night	11% 6% 2 4 4 3 3 3 6% 8% 50%	2090
	21st to end	Night	15% 5% 2 4 4 4 4 4 5% 7% 47%	2090
October	1st to 10th	Night	16% 8% 2 6% 3 3 4 4 5% 7% 40%	2237
	11th to 20th	Night	15% 12% 3 6% 4 3 4 4 5% 6% 38%	2280
	21st to end	Night	15% 12% 3 7% 6% 5% 4 3 5% 7% 33%	2692
November	1st to 10th	Night	13% 13% 4 10% 6% 3 4 3 5% 6% 32%	2679
	11th to 20th	Night	10% 15% 7% 14% 6% 5% 5% 3 4 6% 26%	2660
	21st to end	Night	11% 13% 4 9% 7% 6% 6% 4 6% 6% 27%	2660
December	1st to 10th	Night	8% 14% 5% 13% 9% 7% 7% 6% 5% 6% 20%	2850
	11th to 20th	Night	10% 14% 6% 15% 8% 6% 5% 4 5% 5% 22%	3518
	21st to end	Night	17% 14% 5% 12% 7% 6% 5% 4 5% 6% 20%	5225

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% 8% 11% 17% 4	2219
	11th to 20th	Day	68% 8% 11% 10% 3	2284
	21st to end	Day	68% 6% 8% 13% 5%	2799
February	1st to 10th	Day	57% 6% 13% 16% 7%	1710
	11th to 20th	Day	56% 8% 13% 15% 8% 1	1673
	21st to end	Day	56% 8% 14% 15% 7% 1	1485
March	1st to 10th	Day	53% 7% 16% 19% 6%	3254
	11th to 20th	Day	51% 9% 16% 19% 4	3480
	21st to end	Day	56% 6% 10% 21% 8%	3814
April	1st to 10th	Day	49% 7% 13% 22% 9% 1	2272
	11th to 20th	Day	53% 5% 12% 18% 11% 1	2442
	21st to end	Day	52% 6% 13% 20% 8% 1	2470
May	1st to 10th	Day	47% 6% 13% 21% 11% 1	4209
	11th to 20th	Day	46% 8% 12% 23% 10% 1	4447
	21st to end	Day	48% 8% 12% 24% 7%	5173
June	1st to 10th	Day	41% 8% 18% 24% 9%	2850
	11th to 20th	Day	41% 8% 17% 25% 10%	2850
	21st to end	Day	42% 9% 17% 25% 6% 1	2850
July	1st to 10th	Day	31% 9% 24% 30% 7%	4676
	11th to 20th	Day	28% 7% 22% 33% 10%	4669
	21st to end	Day	29% 8% 19% 35% 8% 1	4871
August	1st to 10th	Day	33% 7% 17% 28% 13% 1	4102
	11th to 20th	Day	35% 7% 17% 33% 8%	4080
	21st to end	Day	33% 5% 21% 32% 8%	4531
September	1st to 10th	Day	34% 5% 16% 32% 12%	2336
	11th to 20th	Day	39% 8% 19% 28% 6% 1	2090
	21st to end	Day	38% 7% 16% 33% 6%	2090
October	1st to 10th	Day	37% 4 14% 28% 16% 1	3197
	11th to 20th	Day	41% 4 10% 28% 16%	3140
	21st to end	Day	50% 5% 13% 25% 7%	3126
November	1st to 10th	Day	55% 6% 13% 18% 7% 1	1604
	11th to 20th	Day	63% 6% 11% 13% 7%	1520
	21st to end	Day	61% 8% 12% 12% 6%	1517
December	1st to 10th	Day	64% 9% 12% 11% 4	1330
	11th to 20th	Day	63% 8% 13% 12% 4	1680
	21st to end	Day	69% 6% 8% 13% 4	2442
January	1st to 10th	Night	61% 9% 12% 14% 4	4737
	11th to 20th	Night	69% 6% 9% 12% 3	4683
	21st to end	Night	64% 7% 10% 14% 4	4866
February	1st to 10th	Night	54% 7% 14% 17% 8%	2470
	11th to 20th	Night	48% 8% 14% 19% 11%	2404
	21st to end	Night	53% 5% 12% 20% 9% 1	1984
March	1st to 10th	Night	50% 8% 13% 20% 9%	3592
	11th to 20th	Night	46% 8% 16% 20% 10%	3480
	21st to end	Night	57% 5% 10% 19% 7% 1	3817
April	1st to 10th	Night	43% 6% 12% 24% 14% 2	1905
	11th to 20th	Night	49% 5% 10% 19% 13% 2	1689
	21st to end	Night	48% 5% 11% 25% 10% 2	1710
May	1st to 10th	Night	43% 7% 13% 26% 10% 1	2759
	11th to 20th	Night	41% 8% 11% 25% 13% 2	2460
	21st to end	Night	41% 6% 12% 30% 11% 1	2414
June	1st to 10th	Night	34% 7% 19% 28% 10% 2	1330
	11th to 20th	Night	35% 9% 14% 27% 13% 2	1330
	21st to end	Night	32% 9% 20% 31% 7% 2	1330
July	1st to 10th	Night	26% 10% 24% 30% 9% 1	2185
	11th to 20th	Night	21% 5% 18% 44% 12%	2178
	21st to end	Night	27% 8% 22% 32% 10% 1	2451
August	1st to 10th	Night	27% 6% 16% 36% 14% 1	2813
	11th to 20th	Night	29% 7% 19% 34% 11% 1	2825
	21st to end	Night	32% 5% 20% 30% 13%	3135
September	1st to 10th	Night	28% 5% 17% 36% 14% 1	1839
	11th to 20th	Night	31% 6% 21% 30% 11% 1	2090
	21st to end	Night	37% 6% 13% 32% 13%	2090
October	1st to 10th	Night	35% 4 12% 34% 13% 2	3731
	11th to 20th	Night	41% 4 12% 30% 13%	3779
	21st to end	Night	48% 5% 11% 27% 9%	4430
November	1st to 10th	Night	53% 6% 13% 19% 8% 1	2679
	11th to 20th	Night	60% 6% 13% 14% 6% 1	2660
	21st to end	Night	56% 7% 17% 14% 6%	2660
December	1st to 10th	Night	62% 7% 14% 13% 3	2850
	11th to 20th	Night	63% 6% 14% 14% 4	3516
	21st to end	Night	64% 6% 11% 14% 5%	5225

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	11% 7% 37% 29% 13% 3	270
	11th to 20th	Day	13% 8% 34% 33% 12%	270
	21st to end	Day	14% 9% 32% 31% 10% 3	297
February	1st to 10th	Day	12% 13% 37% 29% 6% 2	270
	11th to 20th	Day	9% 16% 41% 22% 11% 1	270
	21st to end	Day	10% 6% 45% 30% 8% 1	225
March	1st to 10th	Day	13% 13% 29% 34% 9% 1	270
	11th to 20th	Day	13% 10% 35% 24% 14% 4	270
	21st to end	Day	14% 12% 31% 30% 11% 3	297
April	1st to 10th	Day	15% 12% 36% 25% 9% 2	452
	11th to 20th	Day	19% 12% 32% 25% 10% 1	640
	21st to end	Day	22% 10% 29% 27% 12% 1	650
May	1st to 10th	Day	20% 11% 29% 27% 11% 2	653
	11th to 20th	Day	18% 8% 31% 26% 13% 3	675
	21st to end	Day	18% 9% 27% 28% 15% 2	734
June	1st to 10th	Day	14% 9% 27% 30% 15% 4	680
	11th to 20th	Day	14% 12% 34% 25% 13% 2	680
	21st to end	Day	13% 8% 29% 30% 16% 5%	680
July	1st to 10th	Day	7% 5% 26% 32% 21% 9%	671
	11th to 20th	Day	11% 6% 29% 28% 21% 5%	668
	21st to end	Day	5% 4 27% 35% 22% 7%	739
August	1st to 10th	Day	8% 5% 24% 32% 27% 5%	676
	11th to 20th	Day	11% 6% 23% 31% 20% 9%	665
	21st to end	Day	12% 8% 26% 32% 18% 4	748
September	1st to 10th	Day	12% 9% 30% 30% 17% 2	546
	11th to 20th	Day	14% 11% 34% 28% 11% 2	300
	21st to end	Day	17% 9% 37% 26% 10% 1	300
October	1st to 10th	Day	19% 11% 28% 30% 9% 3	300
	11th to 20th	Day	15% 10% 38% 27% 9%	300
	21st to end	Day	22% 12% 34% 22% 8% 1	330
November	1st to 10th	Day	21% 11% 30% 29% 8% 1	297
	11th to 20th	Day	16% 16% 36% 27% 5% 1	270
	21st to end	Day	18% 13% 41% 24% 4	270
December	1st to 10th	Day	15% 10% 33% 33% 7% 2	270
	11th to 20th	Day	16% 11% 37% 31% 4	270
	21st to end	Day	16% 8% 35% 26% 11% 3	297
January	1st to 10th	Night	11% 9% 35% 32% 12% 2	950
	11th to 20th	Night	15% 8% 37% 31% 9%	950
	21st to end	Night	14% 9% 38% 30% 9%	1045
February	1st to 10th	Night	13% 9% 30% 35% 12% 1	950
	11th to 20th	Night	12% 6% 38% 30% 11% 3	929
	21st to end	Night	11% 7% 37% 30% 13% 2	728
March	1st to 10th	Night	14% 9% 34% 31% 10% 2	683
	11th to 20th	Night	12% 6% 40% 33% 8% 1	570
	21st to end	Night	18% 9% 29% 30% 13% 2	627
April	1st to 10th	Night	16% 8% 35% 30% 10% 1	570
	11th to 20th	Night	18% 10% 31% 30% 10% 1	563
	21st to end	Night	21% 7% 26% 33% 12% 1	570
May	1st to 10th	Night	18% 9% 32% 32% 9% 1	570
	11th to 20th	Night	16% 9% 34% 30% 12%	561
	21st to end	Night	16% 6% 33% 33% 11%	617
June	1st to 10th	Night	13% 5% 28% 39% 14% 1	570
	11th to 20th	Night	14% 5% 32% 36% 12%	570
	21st to end	Night	9% 5% 27% 39% 18% 1	570
July	1st to 10th	Night	6% 2 24% 46% 20% 2	555
	11th to 20th	Night	5% 3 29% 44% 17% 1	552
	21st to end	Night	6% 3 22% 46% 21% 2	624
August	1st to 10th	Night	7% 3 20% 50% 20% 1	567
	11th to 20th	Night	9% 2 26% 37% 21% 3	564
	21st to end	Night	10% 4 28% 39% 18% 1	627
September	1st to 10th	Night	12% 4 29% 38% 14% 2	570
	11th to 20th	Night	14% 4 34% 36% 13%	570
	21st to end	Night	17% 6% 34% 34% 9% 1	570
October	1st to 10th	Night	19% 9% 35% 29% 8%	717
	11th to 20th	Night	21% 9% 36% 28% 7%	760
	21st to end	Night	21% 10% 32% 29% 7% 1	1020
November	1st to 10th	Night	18% 9% 36% 27% 9%	973
	11th to 20th	Night	16% 10% 33% 31% 8% 1	950
	21st to end	Night	17% 12% 41% 24% 5% 1	950
December	1st to 10th	Night	14% 10% 32% 33% 10% 1	950
	11th to 20th	Night	17% 10% 35% 31% 7% 1	950
	21st to end	Night	24% 8% 33% 25% 9% 1	1045

Page generated at 2024-11-07 05:55:45. Version ac07

Copyright © 2024 Attilla Danko.