Mill Ridge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mill Ridge clear sky chart from 2005-11-06 to 2024-10-20.

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	11% 9% 4 8% 5% 5% 5% 4 6% 7% 35%	100957
	Night	11% 9% 4 9% 5% 5% 5% 4 6% 7% 36%	97690
Transparency	Day	44% 10% 12% 19% 12% 3	100770
	Night	43% 10% 13% 18% 13% 3	97547
Seeing	Day	19% 15% 25% 22% 14% 6%	14945
	Night	17% 12% 22% 29% 17% 3	24986

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	10% 10% 5% 15% 6% 5% 3 3 6% 7% 30%	2836
	11th to 20th	Day	10% 11% 6% 14% 6% 7% 4 3 4 4 30%	2840
	21st to end	Day	13% 17% 7% 9% 4 4 4 3 4 5% 31%	3124
February	1st to 10th	Day	12% 10% 5% 10% 6% 5% 4 4 4 6% 33%	1800
	11th to 20th	Day	13% 12% 6% 10% 6% 5% 5% 3 4 6% 32%	1848
	21st to end	Day	14% 13% 3 10% 4 4 4 3 6% 5% 35%	1570
March	1st to 10th	Day	16% 12% 5% 8% 4 5% 4 3 5% 5% 33%	3334
	11th to 20th	Day	10% 9% 3 7% 4 4 4 3 4 5% 46%	3480
	21st to end	Day	14% 11% 3 7% 5% 4 4 4 5% 7% 36%	3815
April	1st to 10th	Day	9% 10% 3 5% 5% 5% 4 5% 7% 9% 40%	2090
	11th to 20th	Day	14% 8% 2 6% 4 5% 4 4 5% 6% 40%	2294
	21st to end	Day	12% 8% 3 7% 5% 4 6% 4 6% 7% 39%	2470
May	1st to 10th	Day	12% 9% 4 9% 6% 6% 6% 4 6% 7% 31%	4082
	11th to 20th	Day	13% 10% 3 9% 6% 6% 6% 5% 7% 6% 28%	4081
	21st to end	Day	8% 7% 2 8% 5% 6% 7% 5% 8% 10% 34%	4476
June	1st to 10th	Day	10% 7% 2 7% 6% 7% 7% 6% 7% 9% 32%	2470
	11th to 20th	Day	6% 6% 3 9% 6% 7% 7% 6% 8% 10% 32%	2470
	21st to end	Day	9% 6% 3 7% 6% 7% 8% 5% 8% 9% 32%	2470
July	1st to 10th	Day	6% 6% 3 8% 7% 7% 7% 6% 8% 10% 33%	4120
	11th to 20th	Day	9% 6% 3 8% 7% 7% 7% 5% 8% 8% 32%	4120
	21st to end	Day	12% 10% 4 13% 9% 8% 7% 6% 7% 8% 16%	4466
August	1st to 10th	Day	10% 6% 3 8% 7% 6% 8% 6% 8% 11% 27%	4104
	11th to 20th	Day	7% 6% 3 8% 7% 6% 7% 6% 9% 10% 30%	4044
	21st to end	Day	6% 5% 2 6% 5% 5% 6% 4 6% 8% 46%	4198
September	1st to 10th	Day	9% 7% 3 9% 5% 5% 6% 4 7% 8% 37%	2090
	11th to 20th	Day	13% 8% 3 9% 6% 4 5% 4 5% 8% 35%	2090
	21st to end	Day	13% 7% 3 7% 4 5% 5% 5% 6% 7% 38%	2090
October	1st to 10th	Day	12% 6% 2 6% 4 4 4 4 5% 7% 46%	2066
	11th to 20th	Day	10% 8% 3 6% 4 3 3 4 5% 6% 49%	1890
	21st to end	Day	12% 9% 2 5% 3 3 4 3 5% 6% 48%	1980
November	1st to 10th	Day	10% 7% 2 5% 4 3 4 3 4 6% 52%	1742
	11th to 20th	Day	9% 9% 2 7% 5% 4 4 3 6% 6% 46%	1710
	21st to end	Day	10% 10% 3 6% 4 4 5% 3 6% 6% 44%	1710
December	1st to 10th	Day	14% 12% 4 9% 5% 5% 4 5% 5% 5% 32%	1710
	11th to 20th	Day	10% 12% 5% 9% 3 4 5% 5% 7% 6% 35%	2153
	21st to end	Day	14% 11% 7% 8% 5% 6% 6% 4 5% 6% 29%	3124
January	1st to 10th	Night	13% 11% 6% 15% 6% 5% 4 3 4 6% 28%	4109
	11th to 20th	Night	13% 10% 4 11% 7% 6% 5% 3 4 6% 31%	4120
	21st to end	Night	14% 16% 5% 9% 5% 4 5% 3 5% 5% 30%	4532
February	1st to 10th	Night	11% 11% 4 9% 5% 5% 4 4 6% 6% 36%	2377
	11th to 20th	Night	16% 13% 4 10% 5% 3 4 3 5% 5% 32%	2218
	21st to end	Night	14% 13% 4 9% 4 5% 4 3 6% 6% 33%	1884
March	1st to 10th	Night	17% 15% 4 10% 6% 5% 5% 3 4 5% 26%	3518
	11th to 20th	Night	10% 9% 3 7% 4 4 4 4 6% 7% 43%	3480
	21st to end	Night	12% 8% 3 7% 5% 5% 4 4 6% 6% 40%	3817
April	1st to 10th	Night	10% 9% 3 6% 5% 4 4 4 6% 7% 41%	2090
	11th to 20th	Night	10% 10% 3 6% 4 4 3 4 4 8% 42%	1850
	21st to end	Night	10% 7% 3 7% 5% 4 4 5% 6% 6% 42%	1710
May	1st to 10th	Night	11% 11% 4 9% 6% 5% 5% 5% 6% 8% 31%	2813
	11th to 20th	Night	12% 11% 4 10% 5% 5% 5% 5% 7% 8% 29%	2812
	21st to end	Night	6% 8% 3 9% 6% 4 5% 5% 8% 10% 35%	3079
June	1st to 10th	Night	8% 6% 3 7% 6% 5% 6% 5% 9% 12% 34%	1710
	11th to 20th	Night	4 5% 2 7% 5% 6% 5% 5% 8% 14% 38%	1710
	21st to end	Night	7% 6% 3 6% 6% 6% 5% 4 8% 11% 39%	1710
July	1st to 10th	Night	7% 6% 3 8% 5% 6% 7% 6% 8% 12% 31%	2840
	11th to 20th	Night	6% 4 3 8% 6% 4 6% 5% 10% 12% 36%	2840
	21st to end	Night	9% 10% 5% 12% 8% 7% 7% 6% 8% 8% 20%	3087
August	1st to 10th	Night	6% 6% 3 9% 6% 6% 6% 6% 9% 12% 32%	2825
	11th to 20th	Night	7% 7% 3 10% 6% 5% 6% 4 8% 8% 35%	2785
	21st to end	Night	5% 4 2 6% 4 3 4 5% 8% 10% 47%	3422
September	1st to 10th	Night	9% 7% 2 8% 5% 5% 5% 5% 7% 8% 40%	2090
	11th to 20th	Night	12% 9% 4 8% 5% 5% 5% 4 6% 8% 36%	2090
	21st to end	Night	11% 7% 3 8% 5% 4 4 3 5% 6% 45%	2090
October	1st to 10th	Night	13% 7% 2 6% 4 3 4 3 4 7% 48%	2113
	11th to 20th	Night	11% 7% 2 6% 4 4 4 3 5% 5% 48%	2275
	21st to end	Night	10% 10% 3 5% 4 4 3 3 4 6% 48%	2376
November	1st to 10th	Night	11% 7% 3 6% 4 3 4 4 5% 5% 48%	2334
	11th to 20th	Night	10% 10% 3 7% 4 2 4 3 5% 7% 45%	2470
	21st to end	Night	10% 10% 3 6% 4 3 3 4 5% 7% 44%	2470
December	1st to 10th	Night	13% 12% 6% 11% 5% 4 5% 4 5% 6% 28%	2470
	11th to 20th	Night	12% 12% 5% 12% 4 4 4 3 4 5% 35%	3042
	21st to end	Night	14% 11% 5% 11% 6% 5% 5% 4 6% 7% 25%	4532

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	45% 9% 10% 18% 15% 3	2837
	11th to 20th	Day	51% 8% 8% 14% 17% 2	2840
	21st to end	Day	53% 6% 7% 15% 18% 1	3124
February	1st to 10th	Day	52% 7% 9% 15% 16% 3	1800
	11th to 20th	Day	53% 7% 9% 15% 14% 3	1858
	21st to end	Day	49% 7% 10% 14% 15% 6%	1570
March	1st to 10th	Day	47% 8% 9% 18% 13% 5%	3334
	11th to 20th	Day	38% 6% 10% 21% 17% 8%	3480
	21st to end	Day	45% 8% 9% 25% 10% 3	3815
April	1st to 10th	Day	39% 9% 12% 21% 17% 3	2090
	11th to 20th	Day	41% 9% 8% 18% 20% 4	2294
	21st to end	Day	42% 9% 12% 23% 12% 2	2470
May	1st to 10th	Day	47% 13% 12% 19% 8% 1	4120
	11th to 20th	Day	49% 13% 12% 20% 5% 1	4085
	21st to end	Day	37% 14% 15% 19% 13% 2	4489
June	1st to 10th	Day	43% 15% 17% 16% 8% 1	2470
	11th to 20th	Day	42% 15% 16% 15% 12% 1	2470
	21st to end	Day	43% 13% 14% 17% 11% 2	2470
July	1st to 10th	Day	41% 15% 17% 18% 8%	4055
	11th to 20th	Day	45% 13% 16% 19% 6% 1	4051
	21st to end	Day	63% 13% 11% 10% 4	4324
August	1st to 10th	Day	46% 15% 17% 19% 4	4091
	11th to 20th	Day	39% 14% 21% 16% 9% 1	4083
	21st to end	Day	33% 11% 14% 32% 9% 1	4198
September	1st to 10th	Day	42% 12% 12% 17% 14% 4	2090
	11th to 20th	Day	46% 9% 10% 18% 14% 1	2090
	21st to end	Day	44% 8% 13% 17% 14% 4	2090
October	1st to 10th	Day	36% 8% 10% 18% 22% 5%	2066
	11th to 20th	Day	35% 6% 9% 22% 20% 8%	1890
	21st to end	Day	37% 6% 8% 23% 22% 6%	1980
November	1st to 10th	Day	33% 6% 8% 19% 26% 8%	1742
	11th to 20th	Day	37% 6% 8% 20% 23% 5%	1710
	21st to end	Day	39% 6% 9% 22% 19% 5%	1710
December	1st to 10th	Day	51% 8% 9% 17% 13% 3	1710
	11th to 20th	Day	43% 7% 10% 17% 19% 3	2150
	21st to end	Day	48% 9% 10% 21% 10% 1	3124
January	1st to 10th	Night	53% 8% 8% 13% 14% 3	4109
	11th to 20th	Night	50% 6% 7% 12% 20% 4	4120
	21st to end	Night	53% 7% 7% 13% 18% 1	4532
February	1st to 10th	Night	46% 7% 11% 18% 15% 3	2377
	11th to 20th	Night	53% 6% 8% 16% 13% 4	2219
	21st to end	Night	50% 8% 10% 15% 13% 4	1884
March	1st to 10th	Night	54% 10% 10% 11% 12% 3	3518
	11th to 20th	Night	37% 8% 11% 22% 15% 7%	3480
	21st to end	Night	41% 9% 11% 23% 13% 3	3817
April	1st to 10th	Night	39% 8% 14% 21% 15% 3	2090
	11th to 20th	Night	40% 8% 10% 20% 19% 4	1850
	21st to end	Night	39% 9% 13% 26% 13% 1	1710
May	1st to 10th	Night	44% 13% 15% 21% 7% 1	2840
	11th to 20th	Night	45% 15% 14% 21% 5%	2813
	21st to end	Night	34% 17% 17% 23% 8% 1	3087
June	1st to 10th	Night	37% 14% 21% 18% 9%	1710
	11th to 20th	Night	33% 15% 22% 21% 9% 1	1710
	21st to end	Night	36% 12% 19% 19% 11% 2	1710
July	1st to 10th	Night	42% 15% 18% 19% 6%	2795
	11th to 20th	Night	35% 17% 23% 19% 4 1	2786
	21st to end	Night	57% 15% 13% 11% 4	2988
August	1st to 10th	Night	40% 15% 23% 18% 4	2814
	11th to 20th	Night	39% 15% 21% 17% 7%	2812
	21st to end	Night	29% 11% 19% 33% 9% 1	3422
September	1st to 10th	Night	40% 10% 15% 19% 13% 3	2090
	11th to 20th	Night	44% 10% 14% 16% 15% 1	2090
	21st to end	Night	39% 8% 12% 21% 17% 3	2090
October	1st to 10th	Night	36% 8% 12% 18% 22% 4	2113
	11th to 20th	Night	35% 8% 10% 22% 18% 5%	2275
	21st to end	Night	35% 6% 7% 21% 23% 7%	2376
November	1st to 10th	Night	36% 8% 9% 20% 22% 6%	2334
	11th to 20th	Night	38% 7% 7% 20% 22% 6%	2470
	21st to end	Night	39% 7% 7% 25% 18% 4	2470
December	1st to 10th	Night	53% 9% 10% 15% 10% 3	2470
	11th to 20th	Night	50% 7% 8% 13% 18% 4	3044
	21st to end	Night	50% 11% 13% 15% 10% 1	4532

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	31% 29% 29% 10% 1	270
	11th to 20th	Day	39% 22% 26% 11% 1	270
	21st to end	Day	32% 29% 29% 7% 3	297
February	1st to 10th	Day	29% 26% 34% 10% 1	270
	11th to 20th	Day	39% 33% 23% 5%	270
	21st to end	Day	40% 26% 28% 4 1	225
March	1st to 10th	Day	27% 24% 30% 12% 6%	393
	11th to 20th	Day	28% 28% 26% 13% 4 1	460
	21st to end	Day	27% 26% 27% 16% 5%	506
April	1st to 10th	Day	25% 22% 26% 18% 8% 1	460
	11th to 20th	Day	22% 22% 25% 21% 9% 2	452
	21st to end	Day	21% 18% 27% 21% 10% 3	460
May	1st to 10th	Day	21% 17% 30% 17% 11% 5%	463
	11th to 20th	Day	18% 14% 25% 24% 12% 6%	487
	21st to end	Day	13% 11% 25% 26% 16% 9%	529
June	1st to 10th	Day	12% 9% 29% 26% 18% 7%	490
	11th to 20th	Day	8% 5% 27% 27% 24% 10%	490
	21st to end	Day	10% 10% 30% 25% 16% 10%	490
July	1st to 10th	Day	9% 5% 19% 29% 23% 15%	485
	11th to 20th	Day	9% 5% 16% 30% 24% 15%	484
	21st to end	Day	10% 5% 19% 27% 26% 13%	532
August	1st to 10th	Day	14% 8% 20% 24% 20% 13%	486
	11th to 20th	Day	11% 7% 21% 27% 23% 12%	479
	21st to end	Day	11% 3 15% 29% 25% 16%	539
September	1st to 10th	Day	9% 7% 17% 32% 25% 11%	490
	11th to 20th	Day	13% 8% 20% 24% 27% 9%	490
	21st to end	Day	19% 6% 21% 29% 20% 4	490
October	1st to 10th	Day	17% 8% 25% 26% 18% 6%	490
	11th to 20th	Day	16% 16% 24% 25% 16% 2	486
	21st to end	Day	20% 17% 22% 29% 11% 2	495
November	1st to 10th	Day	16% 18% 28% 26% 10% 2	340
	11th to 20th	Day	23% 20% 34% 18% 4	270
	21st to end	Day	20% 21% 36% 16% 6% 1	270
December	1st to 10th	Day	29% 27% 30% 11% 3	270
	11th to 20th	Day	25% 23% 32% 16% 5%	270
	21st to end	Day	26% 23% 36% 12% 3	297
January	1st to 10th	Night	25% 21% 28% 22% 4	760
	11th to 20th	Night	26% 20% 28% 21% 5%	760
	21st to end	Night	22% 21% 32% 22% 2	836
February	1st to 10th	Night	21% 18% 30% 27% 4	760
	11th to 20th	Night	30% 22% 30% 17% 1	743
	21st to end	Night	27% 25% 30% 17% 1	628
March	1st to 10th	Night	22% 19% 30% 24% 4	760
	11th to 20th	Night	24% 19% 28% 20% 8% 1	760
	21st to end	Night	21% 18% 32% 23% 6%	836
April	1st to 10th	Night	22% 17% 28% 25% 8%	760
	11th to 20th	Night	19% 15% 27% 27% 10% 1	626
	21st to end	Night	15% 12% 25% 36% 11% 1	570
May	1st to 10th	Night	16% 12% 26% 28% 17% 1	570
	11th to 20th	Night	13% 8% 24% 34% 20% 2	561
	21st to end	Night	11% 4 15% 37% 30% 4	617
June	1st to 10th	Night	8% 4 16% 40% 28% 4	570
	11th to 20th	Night	6% 4 14% 36% 31% 8%	570
	21st to end	Night	9% 3 13% 38% 33% 4	570
July	1st to 10th	Night	12% 2 11% 31% 38% 6%	555
	11th to 20th	Night	9% 3 9% 30% 41% 8%	552
	21st to end	Night	8% 3 8% 32% 39% 10%	624
August	1st to 10th	Night	9% 2 9% 34% 41% 5%	567
	11th to 20th	Night	10% 5% 10% 34% 35% 5%	564
	21st to end	Night	11% 3 8% 33% 38% 7%	660
September	1st to 10th	Night	11% 5% 12% 33% 33% 6%	760
	11th to 20th	Night	15% 5% 15% 31% 29% 5%	760
	21st to end	Night	16% 5% 18% 33% 26% 3	760
October	1st to 10th	Night	16% 8% 19% 29% 23% 6%	760
	11th to 20th	Night	16% 12% 22% 31% 16% 2	759
	21st to end	Night	16% 15% 21% 32% 12% 3	792
November	1st to 10th	Night	16% 9% 21% 34% 16% 3	740
	11th to 20th	Night	20% 14% 24% 31% 10% 1	760
	21st to end	Night	18% 15% 25% 29% 11% 1	760
December	1st to 10th	Night	24% 18% 26% 27% 6%	760
	11th to 20th	Night	20% 18% 26% 29% 7% 1	760
	21st to end	Night	25% 18% 27% 26% 4	836

Page generated at 2024-10-17 13:09:43. Version ac07

Copyright © 2024 Attilla Danko.