Magazine Mountain
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Magazine Mountain clear sky chart from 2005-11-06 to 2024-09-14.

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% 6% 2 6% 4 4 4 3 5% 7% 45%	100244
	Night	13% 6% 2 5% 4 3 3 3 5% 6% 50%	97705
Transparency	Day	39% 4 10% 25% 18% 4	100054
	Night	35% 3 10% 25% 21% 5%	97566
Seeing	Day	15% 9% 21% 26% 22% 7%	15230
	Night	15% 8% 20% 35% 20% 2	24981

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	17% 8% 3 5% 4 3 3 2 3 5% 46%	2847
	11th to 20th	Day	11% 8% 2 7% 4 3 3 3 4 5% 50%	2850
	21st to end	Day	24% 7% 2 5% 3 2 2 2 3 4 46%	3135
February	1st to 10th	Day	20% 9% 2 5% 3 4 3 3 3 5% 43%	1710
	11th to 20th	Day	17% 8% 2 6% 3 3 3 3 5% 5% 44%	1707
	21st to end	Day	19% 9% 3 7% 4 4 3 2 5% 5% 38%	1703
March	1st to 10th	Day	20% 9% 3 6% 4 3 3 2 4 5% 43%	3436
	11th to 20th	Day	14% 7% 2 6% 4 4 4 4 4 6% 46%	3480
	21st to end	Day	16% 8% 3 7% 4 3 3 3 4 6% 41%	3814
April	1st to 10th	Day	13% 6% 2 7% 5% 5% 4 3 5% 6% 44%	2218
	11th to 20th	Day	17% 5% 3 5% 4 3 4 3 4 6% 43%	2254
	21st to end	Day	18% 8% 2 6% 5% 4 4 3 4 6% 40%	2280
May	1st to 10th	Day	18% 8% 3 7% 5% 4 4 3 5% 6% 37%	3921
	11th to 20th	Day	13% 6% 2 7% 4 5% 5% 4 5% 7% 41%	4082
	21st to end	Day	16% 7% 3 8% 5% 6% 5% 4 6% 7% 34%	4477
June	1st to 10th	Day	9% 7% 2 7% 5% 5% 5% 4 7% 9% 41%	2470
	11th to 20th	Day	5% 4 2 6% 6% 6% 6% 6% 6% 9% 44%	2470
	21st to end	Day	4 4 1 5% 5% 5% 5% 5% 7% 10% 50%	2470
July	1st to 10th	Day	10% 5% 2 5% 5% 5% 5% 4 7% 9% 44%	4120
	11th to 20th	Day	5% 3 1 4 4 4 4 4 6% 8% 55%	4120
	21st to end	Day	9% 6% 3 7% 6% 6% 6% 5% 8% 10% 34%	4465
August	1st to 10th	Day	4 2 1 4 4 4 4 4 6% 9% 58%	4104
	11th to 20th	Day	10% 5% 2 6% 4 4 4 4 6% 10% 44%	3887
	21st to end	Day	5% 3 1 4 4 5% 5% 4 7% 9% 53%	4180
September	1st to 10th	Day	11% 5% 2 5% 3 4 4 3 6% 7% 49%	2280
	11th to 20th	Day	13% 5% 2 5% 4 4 4 4 5% 7% 48%	2099
	21st to end	Day	9% 5% 2 5% 4 3 4 3 5% 6% 54%	1926
October	1st to 10th	Day	8% 4 2 6% 4 4 4 3 4 6% 55%	1800
	11th to 20th	Day	14% 6% 2 4 3 3 3 3 4 5% 55%	1800
	21st to end	Day	19% 6% 1 5% 3 3 3 2 4 4 49%	1980
November	1st to 10th	Day	11% 5% 1 4 3 3 4 3 4 5% 55%	1858
	11th to 20th	Day	11% 6% 2 5% 3 3 3 3 5% 6% 54%	1900
	21st to end	Day	17% 7% 2 6% 3 3 3 3 3 5% 48%	1660
December	1st to 10th	Day	17% 5% 2 5% 3 4 3 3 5% 6% 47%	1520
	11th to 20th	Day	13% 9% 3 7% 5% 4 5% 3 4 5% 43%	2086
	21st to end	Day	17% 11% 3 7% 5% 4 5% 3 4 5% 36%	3135
January	1st to 10th	Night	15% 7% 4 6% 4 4 3 3 4 5% 45%	4108
	11th to 20th	Night	13% 6% 2 4 3 2 2 2 3 5% 57%	4120
	21st to end	Night	23% 7% 2 4 3 2 2 2 3 5% 47%	4532
February	1st to 10th	Night	18% 8% 2 6% 5% 2 3 3 5% 5% 43%	2470
	11th to 20th	Night	16% 8% 2 6% 4 3 3 2 4 6% 47%	2358
	21st to end	Night	18% 7% 3 5% 3 3 3 3 4 5% 47%	1765
March	1st to 10th	Night	21% 7% 3 5% 3 3 3 2 4 5% 43%	3419
	11th to 20th	Night	16% 7% 2 5% 3 3 3 3 4 5% 49%	3480
	21st to end	Night	14% 6% 3 6% 4 4 4 3 5% 7% 43%	3817
April	1st to 10th	Night	13% 6% 2 5% 4 3 3 3 5% 7% 49%	1960
	11th to 20th	Night	12% 6% 3 5% 4 4 4 4 5% 6% 49%	1875
	21st to end	Night	16% 6% 2 5% 4 3 4 3 5% 6% 45%	1900
May	1st to 10th	Night	15% 7% 3 7% 4 4 4 3 4 7% 41%	2962
	11th to 20th	Night	13% 6% 2 6% 4 5% 4 4 6% 7% 43%	2823
	21st to end	Night	16% 7% 2 5% 5% 3 4 3 6% 7% 41%	3090
June	1st to 10th	Night	5% 4 1 5% 3 4 4 4 6% 10% 55%	1710
	11th to 20th	Night	4 4 1 3 3 2 4 3 7% 11% 59%	1710
	21st to end	Night	4 2 2 3 2 3 3 3 6% 8% 63%	1710
July	1st to 10th	Night	7% 4 2 5% 3 5% 5% 4 6% 9% 49%	2850
	11th to 20th	Night	5% 3 1 3 3 3 3 3 5% 8% 63%	2850
	21st to end	Night	6% 6% 2 7% 5% 5% 4 4 7% 9% 44%	3098
August	1st to 10th	Night	2 2 1 3 4 4 3 3 6% 9% 64%	2836
	11th to 20th	Night	5% 3 1 4 4 4 4 3 6% 8% 57%	2946
	21st to end	Night	4 3 1 4 3 3 5% 3 6% 9% 58%	3476
September	1st to 10th	Night	8% 5% 2 4 3 3 4 3 5% 6% 58%	1900
	11th to 20th	Night	10% 5% 2 6% 3 4 3 4 5% 7% 52%	1934
	21st to end	Night	8% 4 1 4 3 3 3 3 6% 6% 58%	2015
October	1st to 10th	Night	8% 4 1 4 3 3 3 3 5% 7% 60%	2160
	11th to 20th	Night	13% 5% 2 4 2 2 3 2 4 4 59%	2160
	21st to end	Night	17% 6% 2 4 3 2 2 2 4 4 54%	2376
November	1st to 10th	Night	12% 4 2 4 3 2 3 3 3 6% 57%	2220
	11th to 20th	Night	12% 4 2 4 3 2 4 3 5% 5% 57%	2280
	21st to end	Night	15% 6% 2 5% 4 3 3 3 4 6% 50%	2505
December	1st to 10th	Night	17% 6% 2 5% 4 4 3 2 3 6% 47%	2660
	11th to 20th	Night	15% 8% 2 5% 5% 4 3 3 4 5% 47%	3098
	21st to end	Night	17% 7% 3 7% 4 4 4 4 5% 6% 41%	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	43% 1 5% 25% 22% 3	2848
	11th to 20th	Day	38% 2 11% 23% 22% 4	2850
	21st to end	Day	45% 1 6% 19% 21% 8%	3135
February	1st to 10th	Day	46% 2 10% 21% 17% 4	1710
	11th to 20th	Day	43% 3 6% 23% 19% 5%	1716
	21st to end	Day	49% 2 6% 17% 18% 8%	1703
March	1st to 10th	Day	47% 1 6% 17% 17% 11%	3436
	11th to 20th	Day	41% 2 10% 23% 19% 4	3480
	21st to end	Day	45% 2 9% 25% 17% 1	3814
April	1st to 10th	Day	41% 3 9% 21% 21% 5%	2218
	11th to 20th	Day	42% 3 9% 22% 18% 6%	2254
	21st to end	Day	46% 4 7% 23% 18% 2	2280
May	1st to 10th	Day	50% 3 8% 22% 15% 2	3956
	11th to 20th	Day	41% 3 11% 27% 16% 1	4086
	21st to end	Day	49% 4 11% 20% 14% 2	4489
June	1st to 10th	Day	38% 6% 14% 26% 15% 2	2470
	11th to 20th	Day	34% 6% 14% 26% 19% 2	2470
	21st to end	Day	28% 7% 14% 28% 20% 4	2470
July	1st to 10th	Day	35% 5% 18% 29% 11% 2	4056
	11th to 20th	Day	25% 5% 10% 36% 21% 2	4051
	21st to end	Day	42% 6% 17% 25% 8% 1	4325
August	1st to 10th	Day	23% 4 15% 29% 23% 6%	4090
	11th to 20th	Day	36% 5% 15% 30% 13% 1	3926
	21st to end	Day	26% 5% 16% 35% 16% 2	4179
September	1st to 10th	Day	34% 4 10% 25% 18% 9%	2280
	11th to 20th	Day	35% 5% 10% 22% 22% 5%	2099
	21st to end	Day	31% 4 9% 21% 27% 7%	1926
October	1st to 10th	Day	30% 3 8% 22% 28% 8%	1800
	11th to 20th	Day	33% 3 5% 20% 28% 11%	1800
	21st to end	Day	39% 3 7% 23% 20% 9%	1980
November	1st to 10th	Day	32% 3 7% 27% 24% 7%	1858
	11th to 20th	Day	31% 3 7% 24% 27% 8%	1900
	21st to end	Day	41% 2 7% 19% 26% 5%	1660
December	1st to 10th	Day	38% 2 10% 25% 19% 5%	1520
	11th to 20th	Day	44% 2 5% 20% 25% 5%	2084
	21st to end	Day	49% 3 7% 20% 15% 5%	3135
January	1st to 10th	Night	43% 2 5% 21% 26% 3	4108
	11th to 20th	Night	32% 1 13% 25% 25% 4	4120
	21st to end	Night	43% 1 10% 19% 23% 5%	4532
February	1st to 10th	Night	43% 3 7% 25% 17% 5%	2470
	11th to 20th	Night	40% 2 8% 23% 20% 7%	2359
	21st to end	Night	41% 2 7% 20% 21% 9%	1765
March	1st to 10th	Night	45% 2 8% 17% 18% 11%	3419
	11th to 20th	Night	39% 3 7% 28% 17% 7%	3480
	21st to end	Night	41% 3 10% 27% 17% 2	3817
April	1st to 10th	Night	35% 3 10% 22% 21% 9%	1960
	11th to 20th	Night	36% 3 8% 23% 20% 9%	1875
	21st to end	Night	39% 4 10% 24% 21% 2	1900
May	1st to 10th	Night	45% 4 10% 23% 14% 4	2992
	11th to 20th	Night	40% 3 14% 26% 15% 1	2824
	21st to end	Night	43% 4 14% 24% 13% 3	3099
June	1st to 10th	Night	25% 5% 15% 33% 19% 3	1710
	11th to 20th	Night	20% 5% 12% 35% 24% 3	1710
	21st to end	Night	19% 4 14% 31% 25% 6%	1710
July	1st to 10th	Night	30% 6% 20% 26% 17% 2	2805
	11th to 20th	Night	19% 4 11% 39% 25% 2	2796
	21st to end	Night	35% 6% 17% 28% 14% 1	2999
August	1st to 10th	Night	17% 4 15% 34% 26% 4	2826
	11th to 20th	Night	25% 4 19% 33% 17% 2	2973
	21st to end	Night	23% 5% 14% 32% 24% 3	3476
September	1st to 10th	Night	28% 4 9% 28% 22% 9%	1900
	11th to 20th	Night	32% 5% 10% 23% 24% 6%	1934
	21st to end	Night	26% 4 8% 24% 31% 8%	2015
October	1st to 10th	Night	25% 3 12% 24% 25% 10%	2160
	11th to 20th	Night	30% 2 6% 19% 32% 12%	2160
	21st to end	Night	35% 2 7% 21% 24% 11%	2376
November	1st to 10th	Night	30% 3 7% 24% 26% 10%	2220
	11th to 20th	Night	30% 3 6% 25% 27% 10%	2280
	21st to end	Night	36% 3 7% 22% 27% 6%	2505
December	1st to 10th	Night	40% 2 8% 21% 22% 6%	2660
	11th to 20th	Night	41% 3 6% 22% 22% 6%	3099
	21st to end	Night	43% 3 7% 25% 18% 4	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	24% 14% 33% 20% 8%	270
	11th to 20th	Day	21% 20% 34% 19% 6%	270
	21st to end	Day	22% 20% 32% 18% 7% 1	297
February	1st to 10th	Day	27% 14% 35% 17% 7%	270
	11th to 20th	Day	25% 20% 33% 17% 4 1	270
	21st to end	Day	33% 22% 30% 12% 3	225
March	1st to 10th	Day	24% 16% 32% 22% 5%	270
	11th to 20th	Day	27% 22% 33% 16% 2	270
	21st to end	Day	23% 21% 37% 15% 3 1	297
April	1st to 10th	Day	22% 17% 31% 19% 9% 2	398
	11th to 20th	Day	24% 13% 31% 22% 9% 1	452
	21st to end	Day	23% 12% 32% 23% 8% 2	460
May	1st to 10th	Day	19% 13% 29% 27% 12%	554
	11th to 20th	Day	16% 7% 26% 28% 19% 4	675
	21st to end	Day	11% 7% 25% 33% 18% 7%	734
June	1st to 10th	Day	11% 4 16% 28% 32% 9%	680
	11th to 20th	Day	6% 3 15% 34% 32% 11%	680
	21st to end	Day	4 4 15% 37% 30% 10%	680
July	1st to 10th	Day	7% 2 11% 31% 33% 15%	671
	11th to 20th	Day	5% 2 12% 30% 33% 19%	668
	21st to end	Day	6% 2 9% 28% 38% 18%	739
August	1st to 10th	Day	7% 2 9% 34% 37% 12%	676
	11th to 20th	Day	13% 3 9% 28% 36% 12%	576
	21st to end	Day	9% 2 5% 23% 40% 21%	539
September	1st to 10th	Day	10% 1 8% 24% 41% 15%	490
	11th to 20th	Day	10% 3 12% 27% 35% 13%	365
	21st to end	Day	12% 4 13% 35% 28% 9%	270
October	1st to 10th	Day	6% 4 23% 36% 27% 4	270
	11th to 20th	Day	13% 12% 30% 28% 14% 2	270
	21st to end	Day	28% 15% 22% 21% 11% 2	297
November	1st to 10th	Day	16% 8% 30% 28% 16% 3	270
	11th to 20th	Day	14% 14% 36% 25% 10% 1	270
	21st to end	Day	24% 17% 22% 22% 13% 1	270
December	1st to 10th	Day	20% 14% 34% 20% 8% 2	270
	11th to 20th	Day	24% 15% 30% 24% 7%	270
	21st to end	Day	23% 16% 36% 18% 6%	297
January	1st to 10th	Night	20% 13% 26% 35% 6%	950
	11th to 20th	Night	20% 14% 29% 32% 6%	950
	21st to end	Night	18% 12% 33% 31% 5%	1045
February	1st to 10th	Night	23% 12% 27% 34% 5%	950
	11th to 20th	Night	21% 13% 33% 30% 2	884
	21st to end	Night	23% 14% 32% 29% 2	509
March	1st to 10th	Night	19% 10% 25% 41% 5%	570
	11th to 20th	Night	22% 10% 27% 35% 6% 1	570
	21st to end	Night	22% 9% 29% 33% 8%	627
April	1st to 10th	Night	16% 11% 29% 36% 7%	570
	11th to 20th	Night	14% 12% 28% 33% 12% 1	563
	21st to end	Night	18% 9% 31% 30% 11%	570
May	1st to 10th	Night	13% 6% 25% 42% 13% 1	570
	11th to 20th	Night	14% 7% 19% 38% 21% 2	561
	21st to end	Night	10% 6% 17% 38% 26% 4	617
June	1st to 10th	Night	6% 3 9% 35% 45% 3	570
	11th to 20th	Night	5% 1 7% 44% 39% 3	570
	21st to end	Night	4 2 7% 36% 46% 5%	570
July	1st to 10th	Night	5% 2 7% 31% 48% 8%	555
	11th to 20th	Night	4 1 5% 34% 46% 11%	552
	21st to end	Night	4 1 2 31% 51% 11%	624
August	1st to 10th	Night	4 2 6% 32% 51% 6%	567
	11th to 20th	Night	10% 1 7% 32% 44% 7%	564
	21st to end	Night	7% 3 4 27% 51% 8%	627
September	1st to 10th	Night	10% 1 5% 30% 48% 5%	570
	11th to 20th	Night	12% 2 7% 33% 42% 5%	552
	21st to end	Night	10% 1 10% 36% 38% 4	575
October	1st to 10th	Night	9% 4 11% 38% 35% 4	720
	11th to 20th	Night	14% 6% 22% 40% 18%	720
	21st to end	Night	20% 8% 22% 32% 17% 2	792
November	1st to 10th	Night	13% 6% 19% 43% 19% 1	740
	11th to 20th	Night	14% 9% 25% 39% 14%	760
	21st to end	Night	20% 10% 23% 34% 13%	902
December	1st to 10th	Night	21% 9% 26% 36% 8%	950
	11th to 20th	Night	23% 10% 22% 38% 7%	950
	21st to end	Night	21% 15% 24% 34% 6%	1045

Page generated at 2024-09-11 09:00:07. Version ac07

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