Sturgeon Point State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sturgeon Point State Park clear sky chart from 2005-11-06 to 2026-03-18.

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% 9% 3 8% 5% 5% 5% 4 6% 7% 34%	130640
	Night	13% 11% 4 9% 5% 5% 5% 4 6% 7% 32%	131018
Transparency	Day	47% 5% 13% 22% 12% 1	134158
	Night	51% 5% 12% 21% 11% 1	135587
Seeing	Day	16% 8% 27% 30% 15% 4	17149
	Night	19% 8% 29% 29% 13% 2	26765

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	14% 11% 5% 15% 7% 6% 5% 4 6% 6% 21%	4609
	11th to 20th	Day	11% 15% 6% 14% 9% 7% 6% 4 6% 6% 16%	4679
	21st to end	Day	11% 15% 5% 9% 5% 5% 6% 5% 7% 8% 22%	5357
February	1st to 10th	Day	12% 13% 4 12% 6% 7% 6% 5% 6% 6% 23%	1890
	11th to 20th	Day	11% 13% 4 12% 7% 6% 6% 4 7% 6% 25%	1927
	21st to end	Day	12% 11% 3 12% 8% 6% 7% 4 6% 7% 24%	1730
March	1st to 10th	Day	12% 10% 3 9% 5% 5% 5% 4 5% 7% 34%	4666
	11th to 20th	Day	11% 10% 5% 10% 6% 6% 5% 4 7% 8% 27%	5057
	21st to end	Day	19% 9% 4 10% 6% 5% 5% 3 5% 6% 26%	5465
April	1st to 10th	Day	16% 12% 4 9% 5% 5% 6% 4 5% 5% 30%	2346
	11th to 20th	Day	16% 9% 3 7% 4 5% 4 4 5% 6% 37%	2572
	21st to end	Day	14% 9% 3 8% 5% 4 4 4 6% 6% 37%	2600
May	1st to 10th	Day	16% 8% 3 7% 5% 4 4 3 5% 6% 37%	5888
	11th to 20th	Day	13% 8% 3 8% 4 4 5% 4 6% 7% 39%	5861
	21st to end	Day	13% 7% 2 6% 4 4 4 4 5% 6% 42%	7122
June	1st to 10th	Day	11% 6% 2 6% 5% 4 5% 4 7% 8% 42%	3000
	11th to 20th	Day	11% 5% 2 6% 5% 5% 5% 4 7% 8% 42%	3000
	21st to end	Day	11% 7% 2 7% 4 4 5% 4 7% 8% 41%	3000
July	1st to 10th	Day	10% 5% 2 6% 5% 5% 5% 4 8% 9% 41%	6692
	11th to 20th	Day	7% 6% 3 6% 4 5% 4 4 7% 8% 46%	6360
	21st to end	Day	6% 4 2 5% 4 4 5% 4 7% 10% 50%	6795
August	1st to 10th	Day	9% 4 2 6% 4 5% 5% 5% 8% 9% 44%	4234
	11th to 20th	Day	12% 5% 2 5% 4 4 5% 5% 7% 9% 43%	4174
	21st to end	Day	11% 5% 2 7% 5% 5% 5% 4 6% 9% 41%	4675
September	1st to 10th	Day	9% 6% 2 7% 4 4 5% 4 7% 9% 41%	2307
	11th to 20th	Day	11% 5% 2 5% 3 3 5% 4 6% 9% 47%	2200
	21st to end	Day	15% 7% 3 8% 5% 4 5% 5% 6% 8% 35%	2200
October	1st to 10th	Day	15% 7% 2 8% 5% 4 4 3 5% 7% 40%	2120
	11th to 20th	Day	20% 9% 4 7% 5% 5% 5% 4 6% 7% 29%	2000
	21st to end	Day	19% 10% 3 9% 6% 5% 6% 5% 8% 6% 22%	1993
November	1st to 10th	Day	13% 12% 3 9% 6% 5% 5% 5% 5% 8% 29%	1852
	11th to 20th	Day	13% 13% 5% 9% 5% 7% 6% 5% 7% 7% 25%	1797
	21st to end	Day	19% 13% 5% 9% 6% 6% 5% 4 6% 7% 20%	1680
December	1st to 10th	Day	13% 15% 5% 13% 7% 6% 6% 5% 7% 8% 15%	2548
	11th to 20th	Day	18% 17% 5% 10% 6% 6% 5% 4 5% 6% 19%	2691
	21st to end	Day	24% 22% 9% 12% 6% 5% 4 3 3 4 8%	3553
January	1st to 10th	Night	13% 12% 5% 13% 7% 6% 6% 5% 7% 7% 22%	8310
	11th to 20th	Night	10% 16% 6% 15% 8% 7% 6% 4 6% 6% 15%	8236
	21st to end	Night	8% 12% 5% 12% 7% 6% 6% 4 6% 7% 25%	8844
February	1st to 10th	Night	10% 15% 4 11% 7% 5% 6% 5% 6% 6% 25%	2730
	11th to 20th	Night	12% 13% 4 8% 6% 6% 5% 4 6% 8% 29%	2578
	21st to end	Night	14% 16% 5% 9% 6% 5% 4 4 5% 7% 25%	2076
March	1st to 10th	Night	13% 9% 3 8% 5% 4 4 3 5% 7% 38%	5394
	11th to 20th	Night	10% 9% 3 8% 5% 5% 5% 4 7% 9% 35%	5057
	21st to end	Night	18% 10% 3 8% 5% 4 4 4 5% 5% 34%	5467
April	1st to 10th	Night	18% 10% 2 8% 4 5% 4 4 5% 6% 36%	2069
	11th to 20th	Night	17% 9% 3 8% 4 3 3 3 5% 7% 38%	1777
	21st to end	Night	16% 9% 3 8% 6% 4 4 4 5% 6% 35%	1800
May	1st to 10th	Night	14% 9% 3 8% 6% 5% 5% 4 5% 7% 34%	4053
	11th to 20th	Night	14% 7% 3 9% 5% 4 4 4 6% 7% 37%	4032
	21st to end	Night	17% 6% 3 6% 4 4 4 3 4 6% 42%	3749
June	1st to 10th	Night	12% 6% 2 5% 5% 4 5% 5% 6% 8% 43%	1400
	11th to 20th	Night	10% 5% 2 7% 4 4 4 4 7% 10% 44%	1400
	21st to end	Night	9% 7% 4 7% 4 5% 5% 3 5% 7% 44%	1400
July	1st to 10th	Night	10% 5% 2 7% 5% 4 4 4 7% 8% 45%	3269
	11th to 20th	Night	8% 5% 2 4 4 4 4 4 6% 8% 50%	3620
	21st to end	Night	7% 5% 1 5% 3 4 4 4 5% 9% 52%	4070
August	1st to 10th	Night	8% 5% 2 6% 4 4 3 3 6% 9% 49%	2915
	11th to 20th	Night	12% 5% 1 4 3 2 4 4 6% 9% 50%	2875
	21st to end	Night	7% 6% 3 5% 4 5% 4 4 5% 8% 49%	3223
September	1st to 10th	Night	9% 4 2 6% 4 4 4 5% 6% 8% 47%	2069
	11th to 20th	Night	9% 4 2 5% 3 4 5% 4 6% 7% 51%	2200
	21st to end	Night	15% 6% 3 7% 5% 3 4 5% 5% 8% 39%	2200
October	1st to 10th	Night	15% 6% 2 5% 4 5% 4 4 6% 7% 41%	2280
	11th to 20th	Night	18% 11% 3 6% 4 4 5% 4 5% 6% 33%	2400
	21st to end	Night	20% 12% 3 7% 4 4 5% 3 5% 6% 30%	2845
November	1st to 10th	Night	13% 10% 4 8% 5% 4 4 3 7% 8% 34%	2666
	11th to 20th	Night	13% 12% 3 10% 7% 5% 6% 4 6% 7% 27%	2820
	21st to end	Night	18% 14% 4 8% 5% 5% 6% 4 6% 8% 22%	2940
December	1st to 10th	Night	14% 13% 4 9% 6% 6% 6% 5% 7% 8% 23%	4851
	11th to 20th	Night	13% 17% 6% 11% 6% 6% 5% 4 5% 6% 21%	5736
	21st to end	Night	24% 20% 8% 11% 6% 5% 4 3 4 5% 10%	7667

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	62% 5% 13% 14% 5% 1	4610
	11th to 20th	Day	68% 4 10% 11% 7%	4710
	21st to end	Day	56% 5% 13% 15% 11%	5357
February	1st to 10th	Day	60% 5% 10% 20% 5%	1890
	11th to 20th	Day	57% 5% 13% 15% 10% 1	1936
	21st to end	Day	58% 5% 11% 18% 7% 1	1730
March	1st to 10th	Day	48% 4 17% 19% 11% 2	4669
	11th to 20th	Day	52% 5% 14% 18% 8% 2	5057
	21st to end	Day	56% 6% 11% 16% 10%	5465
April	1st to 10th	Day	54% 5% 9% 20% 10% 1	2346
	11th to 20th	Day	46% 5% 11% 20% 17% 1	2572
	21st to end	Day	46% 5% 13% 19% 14% 3	2600
May	1st to 10th	Day	46% 4 10% 20% 18% 2	5897
	11th to 20th	Day	43% 4 11% 23% 16% 3	5865
	21st to end	Day	40% 4 12% 21% 18% 5%	7122
June	1st to 10th	Day	37% 6% 12% 28% 15% 2	3000
	11th to 20th	Day	38% 6% 11% 26% 17% 2	3000
	21st to end	Day	39% 5% 14% 27% 14% 2	3000
July	1st to 10th	Day	36% 8% 14% 26% 15% 1	6621
	11th to 20th	Day	32% 7% 13% 34% 13% 1	6285
	21st to end	Day	29% 7% 14% 31% 19% 1	6599
August	1st to 10th	Day	33% 7% 14% 32% 13% 1	4221
	11th to 20th	Day	35% 6% 18% 29% 12% 1	4213
	21st to end	Day	36% 7% 16% 31% 9% 1	4674
September	1st to 10th	Day	36% 7% 14% 30% 12% 1	2307
	11th to 20th	Day	33% 6% 17% 31% 12% 1	2200
	21st to end	Day	45% 6% 15% 25% 9%	2200
October	1st to 10th	Day	34% 5% 12% 35% 14% 1	3458
	11th to 20th	Day	49% 5% 10% 24% 12%	3240
	21st to end	Day	54% 5% 12% 21% 8%	3193
November	1st to 10th	Day	52% 6% 11% 22% 8% 1	1852
	11th to 20th	Day	56% 4 18% 14% 8%	1797
	21st to end	Day	65% 4 13% 14% 4	1680
December	1st to 10th	Day	66% 6% 15% 11% 2	2548
	11th to 20th	Day	65% 6% 10% 11% 6%	2691
	21st to end	Day	82% 3 5% 8% 2	3553
January	1st to 10th	Night	61% 6% 12% 16% 5%	8310
	11th to 20th	Night	69% 5% 9% 11% 5%	8280
	21st to end	Night	57% 4 9% 18% 13%	8844
February	1st to 10th	Night	58% 3 12% 18% 8% 1	2730
	11th to 20th	Night	54% 4 12% 22% 8%	2580
	21st to end	Night	60% 3 13% 17% 8%	2076
March	1st to 10th	Night	47% 3 17% 20% 12% 1	5404
	11th to 20th	Night	45% 4 20% 22% 8% 1	5058
	21st to end	Night	52% 4 10% 21% 13% 1	5467
April	1st to 10th	Night	50% 5% 8% 21% 14% 1	2069
	11th to 20th	Night	45% 4 8% 23% 17% 3	1777
	21st to end	Night	49% 4 9% 19% 17% 4	1800
May	1st to 10th	Night	48% 5% 8% 17% 18% 3	4060
	11th to 20th	Night	46% 4 7% 25% 17% 1	4033
	21st to end	Night	44% 3 9% 23% 16% 5%	3750
June	1st to 10th	Night	39% 4 11% 26% 18% 2	1400
	11th to 20th	Night	35% 5% 14% 26% 19% 2	1400
	21st to end	Night	39% 5% 13% 23% 16% 3	1400
July	1st to 10th	Night	35% 5% 15% 23% 18% 3	3232
	11th to 20th	Night	31% 7% 10% 34% 16% 1	3572
	21st to end	Night	29% 6% 15% 30% 19% 1	3952
August	1st to 10th	Night	32% 5% 15% 31% 17% 1	2904
	11th to 20th	Night	32% 5% 17% 31% 13% 2	2902
	21st to end	Night	33% 5% 15% 36% 11% 1	3223
September	1st to 10th	Night	34% 6% 15% 28% 16% 1	2069
	11th to 20th	Night	31% 4 16% 35% 14%	2200
	21st to end	Night	43% 5% 15% 25% 12%	2200
October	1st to 10th	Night	31% 4 12% 35% 17% 1	3722
	11th to 20th	Night	48% 3 11% 24% 14%	3899
	21st to end	Night	48% 4 15% 27% 7%	4595
November	1st to 10th	Night	48% 5% 14% 24% 8% 1	2666
	11th to 20th	Night	56% 5% 14% 18% 7% 1	2820
	21st to end	Night	62% 4 16% 15% 3	2940
December	1st to 10th	Night	59% 7% 19% 12% 3	4851
	11th to 20th	Night	65% 5% 11% 12% 8%	5735
	21st to end	Night	78% 5% 7% 8% 3	7667

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	22% 11% 30% 28% 8% 1	314
	11th to 20th	Day	18% 9% 37% 30% 5% 1	330
	21st to end	Day	24% 10% 26% 32% 7% 1	363
February	1st to 10th	Day	21% 13% 38% 23% 5% 1	330
	11th to 20th	Day	17% 15% 39% 25% 4	330
	21st to end	Day	18% 18% 38% 22% 4	273
March	1st to 10th	Day	20% 11% 40% 22% 6% 1	367
	11th to 20th	Day	21% 12% 33% 24% 8% 1	528
	21st to end	Day	25% 9% 31% 25% 8% 1	550
April	1st to 10th	Day	21% 15% 31% 24% 7% 2	500
	11th to 20th	Day	20% 13% 30% 23% 10% 4	492
	21st to end	Day	19% 9% 32% 28% 10% 2	500
May	1st to 10th	Day	19% 8% 31% 28% 11% 3	503
	11th to 20th	Day	15% 7% 28% 32% 14% 5%	527
	21st to end	Day	13% 6% 24% 36% 17% 4	708
June	1st to 10th	Day	12% 4 27% 39% 16% 2	730
	11th to 20th	Day	15% 4 25% 34% 20% 3	730
	21st to end	Day	14% 5% 21% 38% 18% 4	730
July	1st to 10th	Day	9% 2 19% 39% 26% 5%	721
	11th to 20th	Day	9% 3 21% 39% 21% 6%	718
	21st to end	Day	10% 4 22% 35% 22% 8%	739
August	1st to 10th	Day	11% 3 18% 33% 25% 9%	526
	11th to 20th	Day	8% 2 18% 37% 29% 7%	519
	21st to end	Day	10% 5% 21% 35% 23% 6%	583
September	1st to 10th	Day	12% 7% 23% 32% 19% 8%	530
	11th to 20th	Day	11% 5% 19% 29% 22% 14%	530
	21st to end	Day	18% 5% 23% 28% 18% 7%	530
October	1st to 10th	Day	21% 8% 25% 25% 18% 3	530
	11th to 20th	Day	23% 10% 30% 28% 8% 1	530
	21st to end	Day	24% 9% 33% 24% 9% 1	376
November	1st to 10th	Day	18% 11% 33% 27% 10% 1	330
	11th to 20th	Day	23% 12% 36% 19% 8% 1	280
	21st to end	Day	25% 14% 35% 23% 4	220
December	1st to 10th	Day	21% 11% 33% 25% 8% 1	220
	11th to 20th	Day	27% 15% 40% 14% 5%	220
	21st to end	Day	28% 15% 33% 19% 6%	242
January	1st to 10th	Night	19% 11% 35% 29% 6% 1	1050
	11th to 20th	Night	22% 12% 33% 25% 8%	1050
	21st to end	Night	16% 8% 36% 33% 7% 1	1084
February	1st to 10th	Night	18% 10% 38% 28% 7%	840
	11th to 20th	Night	19% 10% 37% 26% 8%	823
	21st to end	Night	24% 10% 34% 27% 5%	692
March	1st to 10th	Night	16% 10% 35% 29% 9% 1	840
	11th to 20th	Night	18% 11% 33% 28% 9% 1	829
	21st to end	Night	22% 9% 29% 29% 10% 1	880
April	1st to 10th	Night	23% 10% 34% 26% 7% 1	670
	11th to 20th	Night	20% 9% 25% 31% 12% 3	593
	21st to end	Night	21% 8% 28% 31% 12% 1	600
May	1st to 10th	Night	16% 5% 28% 34% 14% 4	600
	11th to 20th	Night	17% 3 21% 38% 19% 2	591
	21st to end	Night	16% 2 22% 31% 26% 3	497
June	1st to 10th	Night	14% 3 22% 40% 20% 2	400
	11th to 20th	Night	13% 3 22% 33% 27% 3	400
	21st to end	Night	11% 3 16% 43% 24% 4	400
July	1st to 10th	Night	7% 1 13% 43% 33% 3	432
	11th to 20th	Night	9% 2 14% 40% 28% 7%	582
	21st to end	Night	9% 2 16% 39% 29% 4	657
August	1st to 10th	Night	9% 3 14% 38% 30% 6%	597
	11th to 20th	Night	10% 2 16% 30% 34% 8%	594
	21st to end	Night	12% 5% 16% 37% 27% 4	660
September	1st to 10th	Night	13% 4 21% 33% 21% 8%	700
	11th to 20th	Night	12% 4 19% 30% 25% 10%	800
	21st to end	Night	19% 7% 19% 28% 22% 6%	800
October	1st to 10th	Night	19% 5% 27% 31% 15% 3	800
	11th to 20th	Night	25% 9% 32% 25% 9% 1	800
	21st to end	Night	28% 10% 30% 26% 6% 1	880
November	1st to 10th	Night	20% 10% 35% 25% 9% 1	820
	11th to 20th	Night	20% 14% 36% 21% 8% 1	840
	21st to end	Night	25% 13% 38% 20% 3	840
December	1st to 10th	Night	23% 14% 37% 20% 5%	919
	11th to 20th	Night	22% 12% 41% 19% 5% 1	1050
	21st to end	Night	28% 12% 36% 19% 5%	1155

Page generated at 2026-03-15 02:23:52. Version ac07

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