Balsam Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Balsam Lake clear sky chart from 2005-11-06 to 2025-10-19.

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% 4 4 4 5% 7% 38%	127201
	Night	11% 9% 4 9% 5% 5% 4 4 5% 6% 37%	122811
Transparency	Day	44% 6% 13% 25% 11% 1	130727
	Night	45% 6% 12% 23% 12% 1	127346
Seeing	Day	16% 11% 32% 26% 13% 3	17398
	Night	15% 9% 33% 31% 10% 1	27210

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	8% 12% 4 18% 9% 5% 5% 3 4 5% 26%	3617
	11th to 20th	Day	5% 11% 5% 13% 8% 8% 8% 7% 9% 6% 20%	3620
	21st to end	Day	6% 14% 8% 15% 5% 4 4 3 5% 5% 30%	4368
February	1st to 10th	Day	8% 12% 5% 10% 7% 5% 6% 5% 6% 7% 30%	1800
	11th to 20th	Day	7% 11% 5% 9% 7% 5% 5% 4 5% 6% 35%	1754
	21st to end	Day	9% 12% 5% 10% 6% 5% 4 4 5% 8% 33%	1575
March	1st to 10th	Day	11% 9% 3 6% 4 4 4 3 5% 8% 44%	4705
	11th to 20th	Day	9% 10% 3 7% 4 6% 4 4 5% 8% 40%	4980
	21st to end	Day	19% 11% 3 10% 6% 4 5% 3 5% 6% 27%	5613
April	1st to 10th	Day	17% 11% 3 7% 4 5% 4 3 7% 7% 32%	2400
	11th to 20th	Day	19% 13% 5% 8% 4 4 4 3 4 6% 30%	2374
	21st to end	Day	20% 12% 3 9% 5% 5% 4 3 5% 5% 30%	2573
May	1st to 10th	Day	13% 6% 2 6% 4 3 3 3 4 6% 49%	6263
	11th to 20th	Day	15% 8% 3 7% 4 4 4 4 5% 6% 41%	6319
	21st to end	Day	16% 8% 3 7% 4 4 4 4 5% 8% 37%	6935
June	1st to 10th	Day	12% 6% 2 5% 4 4 5% 4 7% 8% 44%	2800
	11th to 20th	Day	14% 7% 2 7% 5% 5% 5% 4 7% 9% 35%	2800
	21st to end	Day	12% 5% 2 6% 5% 5% 5% 5% 8% 10% 39%	2800
July	1st to 10th	Day	9% 4 2 5% 3 4 5% 4 6% 9% 47%	6360
	11th to 20th	Day	8% 4 2 5% 3 3 3 3 5% 7% 56%	6360
	21st to end	Day	9% 5% 2 6% 4 4 5% 4 6% 9% 47%	6924
August	1st to 10th	Day	12% 6% 2 6% 4 4 4 4 7% 9% 42%	4310
	11th to 20th	Day	11% 5% 2 6% 5% 5% 5% 4 7% 8% 41%	4171
	21st to end	Day	12% 6% 2 7% 4 5% 5% 3 6% 7% 43%	4421
September	1st to 10th	Day	10% 5% 2 7% 4 5% 4 4 7% 7% 45%	2400
	11th to 20th	Day	12% 6% 2 5% 4 5% 5% 4 7% 7% 44%	2400
	21st to end	Day	15% 7% 2 5% 4 4 3 3 6% 7% 44%	2094
October	1st to 10th	Day	15% 7% 2 5% 4 4 5% 4 5% 7% 43%	2000
	11th to 20th	Day	15% 13% 3 7% 5% 4 4 4 5% 5% 34%	1980
	21st to end	Day	17% 12% 3 9% 5% 3 4 3 4 6% 35%	2013
November	1st to 10th	Day	12% 14% 4 9% 5% 4 4 3 6% 6% 34%	1672
	11th to 20th	Day	13% 13% 7% 10% 8% 4 5% 3 5% 6% 26%	1600
	21st to end	Day	13% 11% 5% 8% 6% 4 5% 3 6% 7% 31%	1600
December	1st to 10th	Day	7% 11% 5% 16% 15% 6% 5% 4 5% 5% 21%	2610
	11th to 20th	Day	10% 16% 8% 11% 6% 5% 4 3 5% 5% 27%	3008
	21st to end	Day	19% 19% 7% 19% 7% 4 4 2 3 3 13%	3982
January	1st to 10th	Night	8% 10% 4 15% 10% 6% 4 3 4 5% 30%	6348
	11th to 20th	Night	6% 10% 5% 12% 7% 7% 8% 9% 9% 6% 21%	6360
	21st to end	Night	7% 15% 8% 13% 6% 5% 4 3 5% 6% 29%	6605
February	1st to 10th	Night	6% 11% 5% 11% 7% 6% 5% 4 6% 7% 33%	2600
	11th to 20th	Night	6% 10% 4 10% 6% 6% 6% 4 5% 7% 37%	2533
	21st to end	Night	10% 13% 4 8% 6% 5% 5% 4 5% 6% 34%	2054
March	1st to 10th	Night	9% 7% 3 7% 5% 4 4 3 5% 7% 47%	5190
	11th to 20th	Night	8% 7% 3 10% 5% 5% 6% 4 7% 9% 35%	4980
	21st to end	Night	22% 11% 4 11% 5% 3 3 3 4 5% 29%	5315
April	1st to 10th	Night	17% 12% 3 7% 5% 4 4 3 4 6% 35%	2000
	11th to 20th	Night	20% 9% 4 7% 4 4 4 3 3 6% 36%	1975
	21st to end	Night	18% 10% 3 6% 5% 4 4 4 5% 7% 34%	1824
May	1st to 10th	Night	12% 7% 2 6% 4 4 4 3 4 5% 50%	3652
	11th to 20th	Night	14% 7% 2 5% 3 3 3 3 5% 7% 50%	3596
	21st to end	Night	13% 9% 3 7% 4 4 4 4 6% 8% 39%	3942
June	1st to 10th	Night	11% 6% 2 6% 4 4 4 4 6% 8% 45%	1600
	11th to 20th	Night	10% 6% 2 7% 5% 5% 4 3 6% 7% 45%	1600
	21st to end	Night	8% 5% 2 5% 4 4 6% 4 7% 8% 46%	1600
July	1st to 10th	Night	8% 3 1 5% 4 4 4 4 6% 9% 51%	3618
	11th to 20th	Night	6% 4 1 4 3 4 4 4 7% 8% 55%	3617
	21st to end	Night	8% 5% 2 5% 4 4 4 4 5% 8% 51%	3947
August	1st to 10th	Night	11% 5% 3 7% 4 4 3 3 6% 8% 47%	2847
	11th to 20th	Night	13% 5% 2 5% 4 3 4 4 7% 8% 46%	2888
	21st to end	Night	11% 7% 3 6% 5% 4 4 4 5% 7% 44%	3480
September	1st to 10th	Night	9% 5% 2 5% 4 4 4 3 5% 8% 52%	2000
	11th to 20th	Night	9% 6% 2 5% 4 3 4 4 6% 8% 51%	2000
	21st to end	Night	13% 5% 2 5% 4 4 3 3 5% 7% 49%	2280
October	1st to 10th	Night	13% 6% 2 5% 3 4 3 3 6% 6% 49%	2400
	11th to 20th	Night	15% 10% 2 7% 4 4 4 4 4 6% 40%	2377
	21st to end	Night	17% 11% 3 6% 5% 4 4 3 5% 7% 35%	2584
November	1st to 10th	Night	14% 10% 3 7% 5% 4 4 3 6% 6% 38%	2624
	11th to 20th	Night	13% 12% 4 12% 5% 5% 4 4 5% 4 33%	2800
	21st to end	Night	13% 10% 4 9% 6% 4 4 4 6% 6% 34%	2800
December	1st to 10th	Night	6% 9% 4 15% 8% 9% 6% 4 5% 7% 26%	4580
	11th to 20th	Night	10% 17% 6% 14% 7% 5% 5% 4 5% 6% 21%	5199
	21st to end	Night	21% 17% 6% 15% 6% 4 4 3 4 4 17%	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	60% 5% 8% 18% 10%	3618
	11th to 20th	Day	59% 5% 8% 17% 10%	3620
	21st to end	Day	56% 5% 15% 17% 8%	4368
February	1st to 10th	Day	52% 5% 13% 20% 9% 1	1800
	11th to 20th	Day	50% 4 11% 24% 9% 1	1763
	21st to end	Day	50% 5% 13% 22% 10% 1	1575
March	1st to 10th	Day	39% 5% 17% 24% 12% 3	4705
	11th to 20th	Day	42% 5% 14% 27% 10% 1	4980
	21st to end	Day	57% 5% 9% 19% 9% 1	5615
April	1st to 10th	Day	51% 6% 10% 19% 13% 1	2400
	11th to 20th	Day	55% 5% 10% 17% 12% 1	2374
	21st to end	Day	55% 6% 10% 19% 9%	2573
May	1st to 10th	Day	36% 5% 13% 28% 16% 2	6302
	11th to 20th	Day	43% 6% 12% 20% 14% 5%	6323
	21st to end	Day	45% 7% 9% 28% 11% 1	6949
June	1st to 10th	Day	36% 8% 14% 30% 12% 1	2800
	11th to 20th	Day	43% 8% 15% 21% 12% 1	2800
	21st to end	Day	37% 9% 18% 26% 9% 1	2800
July	1st to 10th	Day	31% 7% 17% 35% 9%	6291
	11th to 20th	Day	26% 6% 17% 36% 14% 1	6285
	21st to end	Day	32% 7% 15% 30% 16%	6728
August	1st to 10th	Day	37% 7% 15% 26% 13% 1	4295
	11th to 20th	Day	37% 7% 14% 32% 9%	4210
	21st to end	Day	39% 7% 15% 25% 12% 1	4420
September	1st to 10th	Day	36% 7% 14% 32% 11%	2400
	11th to 20th	Day	37% 8% 18% 30% 7%	2400
	21st to end	Day	38% 7% 14% 31% 9% 1	2094
October	1st to 10th	Day	29% 5% 10% 37% 19%	3260
	11th to 20th	Day	40% 6% 10% 26% 17% 2	3220
	21st to end	Day	46% 4 16% 25% 9%	3290
November	1st to 10th	Day	51% 6% 12% 18% 12% 1	1672
	11th to 20th	Day	59% 7% 11% 15% 7% 1	1600
	21st to end	Day	52% 7% 15% 20% 5% 2	1600
December	1st to 10th	Day	64% 6% 11% 14% 4	2610
	11th to 20th	Day	59% 5% 9% 19% 8%	3005
	21st to end	Day	77% 4 7% 7% 5%	3982
January	1st to 10th	Night	56% 5% 10% 17% 12%	6348
	11th to 20th	Night	57% 6% 11% 14% 11%	6360
	21st to end	Night	55% 5% 12% 21% 7%	6605
February	1st to 10th	Night	50% 6% 11% 22% 10% 2	2600
	11th to 20th	Night	46% 6% 13% 24% 9% 1	2534
	21st to end	Night	50% 6% 12% 20% 11% 1	2054
March	1st to 10th	Night	37% 5% 15% 21% 18% 4	5190
	11th to 20th	Night	43% 5% 15% 23% 13% 1	4980
	21st to end	Night	59% 4 10% 14% 13%	5315
April	1st to 10th	Night	50% 6% 7% 20% 16% 1	2000
	11th to 20th	Night	50% 5% 9% 19% 14% 2	1975
	21st to end	Night	48% 6% 10% 21% 14% 1	1824
May	1st to 10th	Night	37% 6% 10% 27% 19% 1	3676
	11th to 20th	Night	34% 5% 13% 22% 19% 7%	3597
	21st to end	Night	42% 7% 12% 26% 12% 1	3950
June	1st to 10th	Night	33% 8% 14% 29% 14% 1	1600
	11th to 20th	Night	37% 7% 14% 23% 18% 2	1600
	21st to end	Night	32% 8% 16% 28% 13% 3	1600
July	1st to 10th	Night	28% 7% 20% 33% 11% 1	3580
	11th to 20th	Night	25% 7% 15% 36% 15% 1	3572
	21st to end	Night	31% 6% 15% 29% 18% 2	3832
August	1st to 10th	Night	36% 6% 12% 29% 14% 3	2838
	11th to 20th	Night	35% 7% 14% 32% 11% 1	2915
	21st to end	Night	37% 7% 16% 27% 10% 2	3480
September	1st to 10th	Night	30% 6% 14% 34% 14% 1	2000
	11th to 20th	Night	30% 6% 18% 32% 14%	2000
	21st to end	Night	35% 6% 13% 33% 13% 1	2280
October	1st to 10th	Night	25% 4 8% 35% 24% 4	3920
	11th to 20th	Night	37% 6% 12% 22% 22% 1	3876
	21st to end	Night	47% 5% 11% 25% 12%	4244
November	1st to 10th	Night	45% 6% 12% 23% 12% 1	2624
	11th to 20th	Night	53% 6% 13% 17% 11% 1	2800
	21st to end	Night	50% 5% 16% 21% 6% 1	2800
December	1st to 10th	Night	56% 8% 16% 17% 3	4580
	11th to 20th	Night	64% 4 10% 16% 6%	5201
	21st to end	Night	71% 5% 8% 12% 5%	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	13% 13% 36% 27% 8% 3	300
	11th to 20th	Day	15% 11% 40% 28% 6% 1	300
	21st to end	Day	13% 9% 45% 22% 10% 1	330
February	1st to 10th	Day	16% 14% 46% 17% 5% 1	300
	11th to 20th	Day	13% 18% 42% 20% 6% 1	300
	21st to end	Day	14% 16% 47% 22% 1	249
March	1st to 10th	Day	16% 14% 42% 19% 8% 1	300
	11th to 20th	Day	19% 12% 39% 22% 6% 1	300
	21st to end	Day	22% 16% 32% 19% 9% 3	391
April	1st to 10th	Day	22% 17% 36% 20% 5% 1	500
	11th to 20th	Day	28% 13% 27% 25% 7% 1	492
	21st to end	Day	25% 14% 31% 21% 8% 2	673
May	1st to 10th	Day	19% 13% 30% 26% 10% 2	703
	11th to 20th	Day	19% 12% 28% 26% 11% 4	725
	21st to end	Day	18% 11% 28% 25% 15% 3	789
June	1st to 10th	Day	11% 8% 29% 32% 17% 2	730
	11th to 20th	Day	14% 10% 36% 28% 10% 2	730
	21st to end	Day	13% 8% 33% 26% 15% 5%	730
July	1st to 10th	Day	8% 5% 24% 30% 24% 10%	721
	11th to 20th	Day	9% 6% 28% 30% 19% 8%	718
	21st to end	Day	7% 4 26% 35% 20% 8%	794
August	1st to 10th	Day	10% 6% 25% 32% 20% 7%	726
	11th to 20th	Day	14% 4 22% 30% 23% 6%	715
	21st to end	Day	12% 7% 24% 32% 20% 5%	653
September	1st to 10th	Day	13% 7% 30% 28% 16% 5%	530
	11th to 20th	Day	13% 6% 27% 33% 18% 3	530
	21st to end	Day	18% 10% 28% 24% 15% 6%	355
October	1st to 10th	Day	16% 15% 28% 22% 15% 3	330
	11th to 20th	Day	20% 19% 32% 22% 6%	324
	21st to end	Day	22% 15% 39% 15% 6% 2	330
November	1st to 10th	Day	20% 16% 35% 22% 7% 1	300
	11th to 20th	Day	20% 18% 36% 21% 4	300
	21st to end	Day	21% 14% 41% 19% 4	300
December	1st to 10th	Day	16% 13% 42% 21% 8%	300
	11th to 20th	Day	18% 20% 39% 20% 4	300
	21st to end	Day	26% 15% 38% 18% 2	330
January	1st to 10th	Night	12% 11% 39% 30% 8%	1000
	11th to 20th	Night	16% 10% 39% 27% 7% 1	1000
	21st to end	Night	17% 10% 37% 29% 6% 1	1100
February	1st to 10th	Night	12% 11% 42% 28% 7% 1	1000
	11th to 20th	Night	10% 12% 43% 27% 6% 1	979
	21st to end	Night	17% 11% 37% 27% 7%	734
March	1st to 10th	Night	16% 12% 38% 26% 7% 1	721
	11th to 20th	Night	15% 12% 40% 28% 6%	600
	21st to end	Night	21% 11% 32% 25% 9% 2	660
April	1st to 10th	Night	23% 11% 35% 25% 6%	600
	11th to 20th	Night	25% 9% 32% 26% 7% 1	593
	21st to end	Night	22% 10% 30% 29% 7% 1	600
May	1st to 10th	Night	19% 10% 35% 30% 6% 1	600
	11th to 20th	Night	17% 9% 29% 33% 10% 2	591
	21st to end	Night	12% 7% 30% 38% 13% 1	650
June	1st to 10th	Night	12% 6% 30% 39% 12% 1	600
	11th to 20th	Night	11% 6% 33% 41% 9% 1	600
	21st to end	Night	9% 6% 27% 42% 15% 2	600
July	1st to 10th	Night	6% 2 23% 41% 26% 2	585
	11th to 20th	Night	7% 4 25% 43% 19% 1	582
	21st to end	Night	5% 2 23% 44% 22% 3	657
August	1st to 10th	Night	9% 3 16% 51% 20% 1	597
	11th to 20th	Night	13% 3 18% 38% 25% 2	594
	21st to end	Night	11% 4 25% 36% 23% 2	660
September	1st to 10th	Night	11% 5% 23% 40% 18% 3	600
	11th to 20th	Night	10% 5% 29% 37% 17% 2	600
	21st to end	Night	14% 9% 30% 31% 16% 1	710
October	1st to 10th	Night	16% 9% 32% 30% 13% 1	800
	11th to 20th	Night	20% 13% 32% 28% 7%	793
	21st to end	Night	23% 12% 30% 27% 8%	836
November	1st to 10th	Night	21% 9% 34% 29% 6% 1	868
	11th to 20th	Night	18% 13% 35% 26% 7%	1000
	21st to end	Night	17% 16% 37% 24% 6%	1000
December	1st to 10th	Night	14% 11% 37% 29% 7% 1	1000
	11th to 20th	Night	19% 13% 37% 22% 7% 1	1000
	21st to end	Night	23% 12% 36% 22% 6%	1100

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