Maramec Spring Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Maramec Spring Park clear sky chart from 2005-11-06 to 2025-12-03.

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% 8% 3 6% 4 4 4 4 5% 7% 43%	126895
	Night	13% 8% 3 7% 4 4 4 3 5% 6% 44%	124059
Transparency	Day	40% 4 11% 25% 17% 3	130491
	Night	40% 4 10% 24% 18% 3	128539
Seeing	Day	18% 12% 28% 25% 14% 4	17047
	Night	18% 12% 30% 26% 12% 1	26847

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	13% 12% 4 12% 5% 4 4 3 4 5% 35%	3734
	11th to 20th	Day	9% 11% 4 8% 4 5% 4 3 5% 5% 43%	4080
	21st to end	Day	17% 9% 4 7% 3 3 3 3 5% 5% 39%	4488
February	1st to 10th	Day	14% 13% 4 9% 5% 4 4 3 4 7% 34%	1800
	11th to 20th	Day	15% 11% 3 6% 4 4 4 4 5% 6% 38%	1876
	21st to end	Day	13% 11% 3 7% 4 3 5% 3 5% 6% 40%	1650
March	1st to 10th	Day	15% 12% 3 5% 3 3 3 2 3 5% 46%	4771
	11th to 20th	Day	10% 6% 2 5% 3 3 4 3 5% 7% 53%	4980
	21st to end	Day	12% 9% 3 7% 6% 5% 6% 4 6% 7% 35%	5632
April	1st to 10th	Day	12% 7% 3 6% 4 4 4 4 5% 8% 44%	2400
	11th to 20th	Day	17% 8% 2 6% 4 5% 4 3 6% 6% 41%	2374
	21st to end	Day	19% 9% 3 7% 5% 5% 4 4 6% 6% 34%	2400
May	1st to 10th	Day	15% 8% 3 8% 5% 5% 5% 4 7% 9% 31%	5488
	11th to 20th	Day	14% 8% 3 7% 5% 5% 5% 4 5% 8% 35%	6174
	21st to end	Day	17% 8% 2 6% 4 4 4 3 5% 6% 41%	6935
June	1st to 10th	Day	10% 5% 2 6% 5% 5% 5% 5% 6% 8% 44%	2800
	11th to 20th	Day	7% 5% 2 5% 4 4 4 4 7% 10% 48%	2800
	21st to end	Day	6% 3 1 5% 4 4 6% 5% 8% 9% 49%	2800
July	1st to 10th	Day	10% 6% 2 6% 4 4 4 3 6% 9% 45%	6360
	11th to 20th	Day	5% 5% 2 7% 5% 6% 6% 5% 7% 11% 41%	6143
	21st to end	Day	6% 5% 2 6% 4 5% 6% 5% 8% 11% 40%	6422
August	1st to 10th	Day	5% 3 2 5% 4 4 4 4 7% 11% 51%	4234
	11th to 20th	Day	11% 6% 2 6% 5% 5% 4 4 5% 8% 45%	3914
	21st to end	Day	7% 5% 2 6% 4 4 4 4 6% 8% 51%	4312
September	1st to 10th	Day	12% 5% 2 4 4 4 4 3 6% 8% 48%	2400
	11th to 20th	Day	10% 5% 2 6% 4 4 4 4 5% 7% 50%	2400
	21st to end	Day	8% 5% 2 6% 4 3 4 4 4 7% 51%	2129
October	1st to 10th	Day	10% 5% 1 4 4 4 3 3 4 6% 57%	2000
	11th to 20th	Day	14% 6% 1 5% 3 3 3 2 4 5% 55%	2000
	21st to end	Day	17% 8% 2 5% 3 3 3 2 4 5% 47%	2200
November	1st to 10th	Day	12% 5% 2 6% 3 3 3 3 4 5% 53%	1934
	11th to 20th	Day	13% 8% 3 5% 4 3 3 2 4 7% 47%	1890
	21st to end	Day	14% 11% 3 5% 4 3 3 3 4 5% 45%	1759
December	1st to 10th	Day	9% 10% 3 7% 4 3 3 3 4 5% 50%	2626
	11th to 20th	Day	12% 11% 5% 7% 4 3 4 3 4 6% 41%	3008
	21st to end	Day	19% 19% 5% 10% 4 4 3 2 3 4 26%	3982
January	1st to 10th	Night	14% 11% 6% 12% 5% 4 4 3 3 5% 32%	6228
	11th to 20th	Night	11% 9% 4 13% 5% 4 6% 3 3 4 39%	5900
	21st to end	Night	17% 11% 5% 8% 4 3 3 2 4 4 40%	6490
February	1st to 10th	Night	17% 10% 4 8% 4 3 3 3 5% 5% 37%	2600
	11th to 20th	Night	15% 9% 3 8% 4 4 2 3 5% 6% 41%	2411
	21st to end	Night	15% 9% 3 8% 4 3 3 3 5% 5% 42%	1980
March	1st to 10th	Night	17% 13% 2 5% 3 3 3 2 4 4 43%	5125
	11th to 20th	Night	11% 9% 2 5% 3 3 3 3 5% 6% 49%	4980
	21st to end	Night	14% 10% 3 8% 5% 5% 5% 4 5% 7% 34%	5295
April	1st to 10th	Night	11% 6% 2 6% 4 3 4 3 5% 8% 49%	2000
	11th to 20th	Night	14% 8% 3 5% 4 3 3 4 5% 6% 46%	1975
	21st to end	Night	19% 7% 3 5% 5% 4 4 4 5% 7% 39%	2000
May	1st to 10th	Night	17% 10% 3 6% 4 3 4 4 6% 8% 36%	4407
	11th to 20th	Night	12% 9% 3 7% 4 3 4 4 5% 8% 41%	3739
	21st to end	Night	17% 8% 3 7% 4 5% 4 3 5% 6% 37%	3942
June	1st to 10th	Night	8% 5% 2 6% 4 4 4 4 6% 8% 50%	1600
	11th to 20th	Night	6% 3 1 4 4 3 3 5% 7% 11% 53%	1600
	21st to end	Night	3 2 1 3 4 3 5% 4 6% 8% 60%	1600
July	1st to 10th	Night	10% 5% 2 6% 3 4 4 4 6% 10% 45%	3618
	11th to 20th	Night	5% 4 2 5% 4 4 4 4 6% 9% 54%	3816
	21st to end	Night	5% 4 2 7% 5% 5% 4 5% 7% 11% 46%	4449
August	1st to 10th	Night	4 3 1 4 3 4 3 3 6% 8% 60%	2926
	11th to 20th	Night	9% 6% 2 6% 4 4 4 3 6% 9% 48%	3135
	21st to end	Night	5% 3 1 4 4 3 4 3 5% 9% 59%	3586
September	1st to 10th	Night	11% 5% 2 5% 4 4 4 3 4 6% 53%	2000
	11th to 20th	Night	8% 5% 2 6% 4 3 3 3 6% 7% 51%	2000
	21st to end	Night	9% 5% 2 5% 4 3 4 3 4 6% 55%	2245
October	1st to 10th	Night	7% 3 1 4 3 3 3 3 5% 8% 61%	2400
	11th to 20th	Night	14% 6% 2 4 3 3 3 3 4 5% 54%	2400
	21st to end	Night	19% 8% 2 4 3 3 3 2 3 5% 48%	2640
November	1st to 10th	Night	11% 6% 2 5% 3 3 3 2 4 5% 55%	2582
	11th to 20th	Night	13% 7% 2 5% 3 3 4 2 5% 7% 50%	2730
	21st to end	Night	16% 11% 3 5% 4 3 3 3 4 5% 44%	2856
December	1st to 10th	Night	12% 8% 3 7% 4 3 3 3 4 6% 47%	4609
	11th to 20th	Night	15% 10% 3 7% 5% 3 4 3 4 5% 43%	5199
	21st to end	Night	22% 17% 5% 9% 5% 4 4 3 4 4 24%	6996

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	53% 3 9% 20% 13% 2	3735
	11th to 20th	Day	44% 3 7% 25% 17% 4	4080
	21st to end	Day	48% 3 9% 15% 17% 9%	4488
February	1st to 10th	Day	52% 4 10% 22% 12% 1	1800
	11th to 20th	Day	47% 5% 10% 19% 14% 5%	1885
	21st to end	Day	45% 4 7% 23% 15% 5%	1650
March	1st to 10th	Day	43% 3 5% 21% 18% 10%	4771
	11th to 20th	Day	33% 3 7% 25% 23% 9%	4980
	21st to end	Day	47% 5% 12% 26% 9% 1	5634
April	1st to 10th	Day	39% 5% 13% 23% 19% 2	2400
	11th to 20th	Day	44% 5% 11% 22% 15% 3	2374
	21st to end	Day	49% 6% 11% 20% 12% 1	2400
May	1st to 10th	Day	48% 7% 12% 21% 13% 1	5523
	11th to 20th	Day	46% 6% 10% 22% 14% 2	6178
	21st to end	Day	44% 5% 8% 25% 17% 1	6949
June	1st to 10th	Day	36% 7% 14% 26% 16% 2	2800
	11th to 20th	Day	30% 6% 13% 29% 18% 3	2800
	21st to end	Day	28% 7% 17% 27% 16% 5%	2800
July	1st to 10th	Day	36% 4 11% 28% 19% 2	6291
	11th to 20th	Day	36% 6% 15% 30% 11% 2	6068
	21st to end	Day	36% 4 17% 32% 10% 1	6240
August	1st to 10th	Day	27% 6% 17% 32% 18%	4220
	11th to 20th	Day	39% 5% 13% 25% 17% 2	3951
	21st to end	Day	31% 4 15% 35% 12% 4	4311
September	1st to 10th	Day	33% 7% 11% 26% 19% 5%	2400
	11th to 20th	Day	35% 4 8% 26% 25% 2	2400
	21st to end	Day	32% 5% 9% 25% 25% 3	2129
October	1st to 10th	Day	18% 3 5% 19% 43% 11%	3260
	11th to 20th	Day	24% 2 6% 22% 36% 11%	3240
	21st to end	Day	32% 3 7% 30% 25% 3	3538
November	1st to 10th	Day	34% 4 10% 23% 23% 6%	1934
	11th to 20th	Day	39% 3 8% 23% 21% 6%	1890
	21st to end	Day	42% 4 9% 27% 17% 1	1759
December	1st to 10th	Day	39% 2 8% 35% 15% 1	2626
	11th to 20th	Day	45% 3 9% 23% 19% 1	3005
	21st to end	Day	63% 4 10% 13% 9% 1	3982
January	1st to 10th	Night	57% 3 8% 19% 12% 1	6228
	11th to 20th	Night	51% 3 6% 23% 15% 2	5900
	21st to end	Night	50% 3 8% 19% 17% 3	6490
February	1st to 10th	Night	50% 4 10% 20% 14% 2	2600
	11th to 20th	Night	45% 3 11% 21% 16% 3	2412
	21st to end	Night	46% 4 8% 22% 16% 4	1980
March	1st to 10th	Night	46% 3 6% 22% 19% 4	5125
	11th to 20th	Night	37% 4 8% 23% 20% 8%	4980
	21st to end	Night	49% 6% 11% 22% 10% 1	5295
April	1st to 10th	Night	34% 5% 12% 27% 19% 3	2000
	11th to 20th	Night	38% 5% 11% 25% 16% 5%	1975
	21st to end	Night	45% 5% 9% 24% 16% 1	2000
May	1st to 10th	Night	46% 7% 13% 20% 12% 2	4437
	11th to 20th	Night	42% 5% 11% 23% 16% 3	3740
	21st to end	Night	47% 6% 11% 22% 13% 2	3950
June	1st to 10th	Night	31% 6% 17% 27% 17% 3	1600
	11th to 20th	Night	24% 8% 14% 29% 22% 4	1600
	21st to end	Night	20% 7% 18% 28% 20% 7%	1600
July	1st to 10th	Night	36% 5% 11% 25% 21% 2	3580
	11th to 20th	Night	29% 4 15% 37% 15% 2	3771
	21st to end	Night	33% 4 18% 32% 13% 1	4320
August	1st to 10th	Night	22% 5% 18% 32% 22% 1	2916
	11th to 20th	Night	34% 4 17% 27% 15% 3	3164
	21st to end	Night	24% 4 15% 38% 17% 3	3586
September	1st to 10th	Night	32% 5% 9% 26% 22% 6%	2000
	11th to 20th	Night	31% 5% 9% 25% 27% 2	2000
	21st to end	Night	30% 6% 9% 24% 28% 3	2245
October	1st to 10th	Night	14% 3 7% 18% 49% 11%	3920
	11th to 20th	Night	23% 2 6% 21% 33% 14%	3899
	21st to end	Night	34% 2 7% 27% 27% 3	4252
November	1st to 10th	Night	32% 4 10% 27% 21% 5%	2582
	11th to 20th	Night	36% 3 8% 24% 23% 5%	2730
	21st to end	Night	44% 3 9% 25% 18% 2	2856
December	1st to 10th	Night	40% 3 9% 32% 15% 1	4609
	11th to 20th	Night	46% 2 9% 23% 19% 1	5201
	21st to end	Night	64% 4 10% 15% 6% 1	6996

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	26% 25% 35% 11% 2	300
	11th to 20th	Day	31% 24% 35% 10%	300
	21st to end	Day	23% 28% 35% 12% 2	330
February	1st to 10th	Day	27% 21% 37% 13% 1	300
	11th to 20th	Day	30% 29% 28% 10% 3	300
	21st to end	Day	27% 24% 37% 12% 1	249
March	1st to 10th	Day	25% 23% 41% 10% 1	300
	11th to 20th	Day	31% 22% 33% 11% 2 1	300
	21st to end	Day	32% 21% 36% 10% 1	397
April	1st to 10th	Day	24% 18% 35% 17% 5%	500
	11th to 20th	Day	28% 20% 29% 16% 5% 1	492
	21st to end	Day	24% 20% 30% 20% 5% 1	500
May	1st to 10th	Day	21% 18% 33% 22% 5% 1	534
	11th to 20th	Day	19% 15% 28% 25% 11% 2	725
	21st to end	Day	14% 12% 34% 23% 14% 4	789
June	1st to 10th	Day	12% 6% 26% 28% 21% 7%	730
	11th to 20th	Day	9% 4 25% 37% 21% 3	730
	21st to end	Day	7% 7% 30% 37% 15% 4	730
July	1st to 10th	Day	12% 4 17% 30% 27% 10%	721
	11th to 20th	Day	7% 4 21% 38% 25% 5%	718
	21st to end	Day	10% 3 16% 34% 29% 7%	794
August	1st to 10th	Day	11% 2 19% 39% 24% 5%	726
	11th to 20th	Day	11% 4 19% 33% 25% 8%	560
	21st to end	Day	12% 2 16% 31% 30% 9%	583
September	1st to 10th	Day	14% 3 15% 36% 25% 6%	530
	11th to 20th	Day	10% 2 19% 31% 25% 12%	530
	21st to end	Day	11% 9% 25% 30% 20% 5%	430
October	1st to 10th	Day	14% 10% 32% 30% 11% 4	330
	11th to 20th	Day	19% 16% 35% 22% 8% 1	330
	21st to end	Day	34% 16% 31% 17% 2	363
November	1st to 10th	Day	18% 15% 41% 19% 6% 2	330
	11th to 20th	Day	22% 19% 38% 14% 5% 1	330
	21st to end	Day	31% 16% 33% 15% 5%	330
December	1st to 10th	Day	18% 28% 32% 14% 6% 2	306
	11th to 20th	Day	24% 23% 36% 13% 3 1	300
	21st to end	Day	29% 26% 32% 10% 2	330
January	1st to 10th	Night	21% 21% 37% 18% 3	1000
	11th to 20th	Night	22% 26% 33% 17% 3	1000
	21st to end	Night	20% 21% 37% 21% 1	1100
February	1st to 10th	Night	23% 20% 38% 17% 2	1000
	11th to 20th	Night	22% 20% 40% 17% 1	856
	21st to end	Night	23% 22% 35% 17% 2	660
March	1st to 10th	Night	25% 17% 37% 19% 2	695
	11th to 20th	Night	24% 15% 36% 22% 3	600
	21st to end	Night	26% 17% 35% 18% 4	660
April	1st to 10th	Night	15% 18% 40% 23% 4	600
	11th to 20th	Night	20% 17% 32% 26% 5% 1	593
	21st to end	Night	24% 12% 36% 21% 8%	600
May	1st to 10th	Night	19% 7% 36% 30% 8%	600
	11th to 20th	Night	18% 7% 31% 29% 15% 1	591
	21st to end	Night	13% 7% 30% 32% 16% 3	650
June	1st to 10th	Night	11% 5% 21% 34% 27% 3	600
	11th to 20th	Night	8% 2 24% 43% 21% 2	600
	21st to end	Night	4 2 27% 45% 21% 2	600
July	1st to 10th	Night	12% 1 13% 35% 33% 6%	585
	11th to 20th	Night	4 2 18% 40% 33% 3	582
	21st to end	Night	7% 1 17% 40% 32% 3	657
August	1st to 10th	Night	7% 2 17% 40% 32% 1	597
	11th to 20th	Night	7% 2 16% 41% 31% 3	594
	21st to end	Night	6% 2 16% 36% 35% 5%	660
September	1st to 10th	Night	14% 2 15% 37% 28% 4	600
	11th to 20th	Night	12% 2 14% 38% 28% 6%	600
	21st to end	Night	11% 6% 25% 31% 23% 5%	750
October	1st to 10th	Night	8% 6% 28% 32% 23% 3	800
	11th to 20th	Night	17% 12% 34% 25% 12% 1	800
	21st to end	Night	25% 14% 32% 23% 6%	880
November	1st to 10th	Night	15% 12% 38% 27% 8%	820
	11th to 20th	Night	20% 15% 34% 24% 8%	840
	21st to end	Night	25% 16% 33% 21% 5%	966
December	1st to 10th	Night	23% 16% 36% 21% 4	1011
	11th to 20th	Night	25% 15% 35% 22% 4	1000
	21st to end	Night	27% 19% 34% 18% 2	1100

Page generated at 2025-11-30 00:00:55. Version ac07

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