Selkirk Shores State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Selkirk Shores State Park clear sky chart from 2005-11-06 to 2026-05-17.

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	18% 11% 4 9% 5% 4 4 3 5% 6% 30%	132247
	Night	20% 15% 5% 10% 5% 4 4 3 4 5% 24%	130559
Transparency	Day	53% 7% 12% 18% 9% 1	135764
	Night	60% 7% 10% 15% 8% 1	135129
Seeing	Day	26% 16% 29% 19% 8% 2	16482
	Night	27% 15% 26% 22% 8% 1	25765

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	16% 22% 10% 20% 8% 4 4 2 3 4 7%	4661
	11th to 20th	Day	12% 25% 8% 21% 10% 5% 4 3 4 3 6%	4650
	21st to end	Day	15% 18% 8% 14% 11% 8% 6% 3 4 4 11%	5641
February	1st to 10th	Day	18% 18% 6% 15% 8% 6% 4 3 3 4 14%	1890
	11th to 20th	Day	19% 16% 6% 13% 6% 5% 5% 3 4 4 17%	1864
	21st to end	Day	20% 17% 5% 12% 7% 4 4 4 5% 6% 18%	1730
March	1st to 10th	Day	19% 17% 5% 10% 5% 5% 3 2 3 4 26%	4667
	11th to 20th	Day	14% 18% 4 8% 4 4 4 3 5% 6% 31%	5090
	21st to end	Day	20% 11% 3 9% 4 4 3 3 4 5% 33%	5838
April	1st to 10th	Day	21% 12% 3 6% 4 4 3 3 4 5% 34%	2520
	11th to 20th	Day	21% 9% 2 6% 4 3 4 3 4 6% 38%	2494
	21st to end	Day	23% 8% 3 6% 4 4 4 4 4 6% 35%	2573
May	1st to 10th	Day	27% 9% 3 7% 4 4 4 3 4 5% 28%	6437
	11th to 20th	Day	17% 8% 3 8% 5% 5% 4 3 5% 6% 37%	6402
	21st to end	Day	24% 8% 2 6% 4 3 4 3 5% 8% 33%	6949
June	1st to 10th	Day	19% 6% 2 6% 4 4 4 4 6% 8% 36%	2800
	11th to 20th	Day	16% 6% 2 5% 5% 4 4 4 7% 9% 38%	2800
	21st to end	Day	15% 6% 2 6% 4 5% 4 4 6% 9% 39%	2800
July	1st to 10th	Day	13% 5% 2 6% 4 4 4 4 7% 10% 41%	6360
	11th to 20th	Day	12% 5% 2 6% 4 4 4 4 6% 9% 42%	6360
	21st to end	Day	13% 4 2 5% 4 4 4 4 5% 9% 47%	6926
August	1st to 10th	Day	17% 6% 2 6% 4 4 4 3 5% 7% 42%	4310
	11th to 20th	Day	16% 6% 2 7% 4 4 4 4 6% 8% 38%	4085
	21st to end	Day	16% 5% 2 5% 3 4 4 4 6% 7% 44%	4312
September	1st to 10th	Day	16% 6% 2 5% 4 4 4 3 5% 8% 44%	2400
	11th to 20th	Day	15% 5% 2 5% 3 3 4 3 5% 8% 46%	2400
	21st to end	Day	18% 7% 2 7% 4 4 5% 4 5% 7% 36%	2127
October	1st to 10th	Day	21% 9% 2 6% 4 5% 4 3 5% 7% 35%	2000
	11th to 20th	Day	24% 10% 3 7% 4 3 5% 3 5% 7% 28%	2000
	21st to end	Day	29% 11% 2 6% 5% 4 4 4 5% 4 24%	2100
November	1st to 10th	Day	18% 14% 3 8% 6% 4 5% 4 5% 6% 28%	1851
	11th to 20th	Day	18% 17% 5% 10% 5% 4 3 4 6% 5% 24%	1736
	21st to end	Day	23% 22% 6% 10% 5% 4 3 3 4 4 16%	1680
December	1st to 10th	Day	21% 29% 8% 13% 6% 4 3 2 3 3 8%	2680
	11th to 20th	Day	21% 23% 9% 12% 5% 4 3 3 4 4 13%	3066
	21st to end	Day	23% 18% 7% 12% 5% 5% 4 3 3 5% 16%	4048
January	1st to 10th	Night	17% 28% 10% 20% 6% 4 3 2 2 2 7%	8234
	11th to 20th	Night	15% 22% 10% 21% 8% 5% 4 2 3 3 6%	8235
	21st to end	Night	15% 16% 7% 18% 11% 8% 5% 3 4 4 9%	8539
February	1st to 10th	Night	18% 20% 7% 15% 7% 5% 3 3 3 4 15%	2730
	11th to 20th	Night	18% 18% 7% 15% 7% 5% 4 3 3 4 16%	2642
	21st to end	Night	18% 18% 6% 13% 6% 5% 4 3 4 5% 18%	2076
March	1st to 10th	Night	20% 13% 7% 11% 8% 4 4 3 4 5% 22%	5390
	11th to 20th	Night	18% 18% 4 8% 4 3 3 3 4 6% 29%	5089
	21st to end	Night	25% 11% 4 9% 4 4 4 3 4 5% 28%	5322
April	1st to 10th	Night	23% 14% 4 7% 4 4 4 3 5% 4 28%	2100
	11th to 20th	Night	23% 11% 2 7% 4 4 3 3 4 5% 34%	2075
	21st to end	Night	23% 9% 2 5% 4 4 3 3 4 6% 35%	2063
May	1st to 10th	Night	31% 10% 3 7% 5% 4 4 3 4 5% 23%	3721
	11th to 20th	Night	17% 9% 3 7% 4 4 4 3 6% 7% 35%	3623
	21st to end	Night	24% 9% 3 6% 3 4 4 3 5% 6% 33%	3926
June	1st to 10th	Night	18% 7% 3 8% 6% 5% 4 3 6% 7% 34%	1600
	11th to 20th	Night	15% 6% 2 6% 5% 4 5% 4 6% 8% 39%	1600
	21st to end	Night	15% 8% 2 7% 5% 4 5% 4 6% 6% 37%	1600
July	1st to 10th	Night	13% 6% 2 7% 5% 5% 4 5% 6% 8% 38%	3600
	11th to 20th	Night	16% 5% 3 7% 4 5% 4 4 5% 6% 41%	3600
	21st to end	Night	12% 6% 2 6% 3 4 3 4 6% 8% 46%	3926
August	1st to 10th	Night	16% 6% 2 6% 4 4 4 3 6% 8% 41%	2836
	11th to 20th	Night	16% 7% 3 7% 5% 4 5% 3 5% 8% 38%	2931
	21st to end	Night	11% 5% 2 6% 5% 6% 5% 4 8% 8% 41%	3586
September	1st to 10th	Night	17% 7% 2 6% 4 5% 4 3 4 7% 42%	2000
	11th to 20th	Night	16% 6% 3 5% 3 3 4 2 5% 6% 47%	2000
	21st to end	Night	18% 7% 2 7% 4 4 4 4 5% 7% 37%	2268
October	1st to 10th	Night	24% 7% 2 7% 5% 5% 4 3 5% 5% 33%	2400
	11th to 20th	Night	25% 9% 3 7% 4 5% 4 4 5% 6% 28%	2400
	21st to end	Night	33% 12% 2 8% 4 3 4 2 4 4 23%	2740
November	1st to 10th	Night	23% 15% 4 6% 5% 5% 4 3 4 5% 27%	2667
	11th to 20th	Night	21% 18% 4 8% 5% 4 3 3 4 5% 25%	2882
	21st to end	Night	24% 23% 5% 9% 5% 4 3 3 4 5% 15%	2940
December	1st to 10th	Night	23% 31% 8% 10% 5% 4 3 2 3 4 7%	4720
	11th to 20th	Night	24% 23% 7% 11% 5% 4 3 3 3 3 13%	5348
	21st to end	Night	27% 19% 5% 10% 5% 5% 3 2 4 4 16%	7150

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	79% 8% 8% 5%	4662
	11th to 20th	Day	80% 8% 5% 4 3	4680
	21st to end	Day	74% 7% 8% 8% 3	5641
February	1st to 10th	Day	72% 7% 9% 10% 2	1890
	11th to 20th	Day	69% 8% 10% 11% 3	1873
	21st to end	Day	68% 7% 11% 10% 4	1730
March	1st to 10th	Day	64% 6% 11% 13% 6% 1	4670
	11th to 20th	Day	53% 8% 20% 10% 8% 1	5090
	21st to end	Day	53% 7% 9% 18% 13% 1	5838
April	1st to 10th	Day	53% 6% 10% 19% 10% 2	2520
	11th to 20th	Day	47% 7% 10% 21% 13% 2	2494
	21st to end	Day	50% 7% 10% 19% 11% 3	2573
May	1st to 10th	Day	58% 7% 9% 15% 9% 1	6448
	11th to 20th	Day	47% 8% 12% 21% 11% 1	6406
	21st to end	Day	49% 8% 13% 20% 10% 1	6949
June	1st to 10th	Day	45% 8% 14% 19% 13% 1	2800
	11th to 20th	Day	41% 9% 14% 24% 10% 2	2800
	21st to end	Day	43% 9% 15% 20% 12% 1	2800
July	1st to 10th	Day	39% 7% 14% 27% 13%	6290
	11th to 20th	Day	37% 8% 14% 27% 13% 1	6285
	21st to end	Day	36% 6% 14% 32% 12%	6728
August	1st to 10th	Day	42% 8% 15% 21% 13% 1	4296
	11th to 20th	Day	43% 7% 17% 25% 8%	4124
	21st to end	Day	38% 7% 15% 32% 8% 1	4312
September	1st to 10th	Day	38% 7% 14% 29% 11% 1	2400
	11th to 20th	Day	36% 7% 12% 30% 14% 1	2400
	21st to end	Day	46% 9% 12% 24% 9% 1	2127
October	1st to 10th	Day	48% 6% 12% 26% 8%	3260
	11th to 20th	Day	49% 6% 14% 21% 9%	3240
	21st to end	Day	49% 7% 16% 20% 7%	3377
November	1st to 10th	Day	56% 9% 13% 13% 8%	1851
	11th to 20th	Day	60% 8% 11% 12% 7% 1	1736
	21st to end	Day	70% 7% 12% 9% 2	1680
December	1st to 10th	Day	83% 5% 7% 4	2680
	11th to 20th	Day	76% 7% 7% 8% 2	3066
	21st to end	Day	70% 6% 9% 12% 4	4048
January	1st to 10th	Night	81% 7% 6% 4 1	8234
	11th to 20th	Night	81% 7% 5% 5% 2	8280
	21st to end	Night	75% 7% 7% 6% 4	8539
February	1st to 10th	Night	72% 6% 9% 10% 3	2730
	11th to 20th	Night	71% 6% 10% 10% 4	2644
	21st to end	Night	67% 7% 12% 10% 4	2076
March	1st to 10th	Night	63% 7% 9% 12% 7% 1	5400
	11th to 20th	Night	54% 7% 17% 14% 5% 3	5090
	21st to end	Night	58% 6% 8% 19% 8% 1	5322
April	1st to 10th	Night	58% 6% 9% 17% 7% 2	2100
	11th to 20th	Night	53% 6% 9% 17% 13% 1	2075
	21st to end	Night	50% 7% 10% 18% 14% 3	2063
May	1st to 10th	Night	62% 7% 8% 11% 10% 2	3727
	11th to 20th	Night	46% 8% 15% 19% 12% 1	3624
	21st to end	Night	50% 8% 11% 17% 14% 1	3927
June	1st to 10th	Night	48% 8% 12% 19% 12% 1	1600
	11th to 20th	Night	41% 9% 13% 19% 16% 1	1600
	21st to end	Night	44% 8% 13% 21% 14% 1	1600
July	1st to 10th	Night	44% 6% 14% 21% 14% 1	3560
	11th to 20th	Night	43% 6% 11% 23% 16% 1	3552
	21st to end	Night	35% 7% 11% 30% 17% 1	3809
August	1st to 10th	Night	42% 7% 15% 24% 12% 1	2826
	11th to 20th	Night	44% 7% 17% 23% 9%	2958
	21st to end	Night	36% 9% 14% 30% 10% 1	3586
September	1st to 10th	Night	42% 8% 13% 24% 12% 1	2000
	11th to 20th	Night	37% 6% 13% 28% 16% 1	2000
	21st to end	Night	44% 8% 13% 23% 11% 1	2268
October	1st to 10th	Night	50% 7% 9% 23% 10% 1	3920
	11th to 20th	Night	51% 9% 12% 17% 11% 1	3899
	21st to end	Night	55% 5% 11% 23% 5% 1	4413
November	1st to 10th	Night	59% 7% 9% 15% 8% 2	2667
	11th to 20th	Night	61% 7% 10% 14% 7% 2	2882
	21st to end	Night	70% 8% 11% 9% 2	2940
December	1st to 10th	Night	84% 6% 6% 4 1	4720
	11th to 20th	Night	75% 7% 6% 10% 2	5348
	21st to end	Night	69% 8% 7% 9% 6%	7150

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	33% 20% 34% 10% 3	220
	11th to 20th	Day	39% 25% 27% 8% 1	220
	21st to end	Day	33% 23% 33% 9% 2	338
February	1st to 10th	Day	35% 27% 27% 10% 2	330
	11th to 20th	Day	37% 25% 31% 7% 1	351
	21st to end	Day	36% 20% 33% 10% 1	446
March	1st to 10th	Day	32% 22% 30% 14% 2	540
	11th to 20th	Day	34% 23% 28% 12% 2	540
	21st to end	Day	35% 21% 29% 11% 4	594
April	1st to 10th	Day	34% 22% 28% 12% 4	540
	11th to 20th	Day	32% 24% 22% 13% 8% 2	532
	21st to end	Day	32% 20% 28% 14% 6% 1	540
May	1st to 10th	Day	29% 17% 30% 16% 6% 2	543
	11th to 20th	Day	20% 15% 32% 24% 7% 1	551
	21st to end	Day	21% 9% 31% 23% 14% 2	573
June	1st to 10th	Day	25% 13% 28% 25% 8% 2	530
	11th to 20th	Day	17% 14% 31% 26% 10% 2	530
	21st to end	Day	19% 14% 33% 23% 9% 1	530
July	1st to 10th	Day	13% 8% 32% 28% 16% 3	525
	11th to 20th	Day	14% 9% 29% 31% 16% 2	524
	21st to end	Day	13% 9% 33% 31% 12% 2	576
August	1st to 10th	Day	14% 8% 28% 29% 17% 4	526
	11th to 20th	Day	16% 8% 24% 31% 15% 5%	519
	21st to end	Day	15% 12% 31% 24% 14% 4	583
September	1st to 10th	Day	16% 11% 25% 26% 16% 6%	530
	11th to 20th	Day	12% 9% 24% 26% 18% 10%	530
	21st to end	Day	19% 12% 30% 22% 14% 3	530
October	1st to 10th	Day	24% 12% 29% 19% 12% 4	530
	11th to 20th	Day	28% 22% 27% 15% 7% 1	530
	21st to end	Day	39% 13% 30% 15% 3	528
November	1st to 10th	Day	33% 19% 26% 16% 6%	425
	11th to 20th	Day	35% 22% 26% 13% 3 1	276
	21st to end	Day	38% 25% 29% 8%	220
December	1st to 10th	Day	36% 25% 26% 10% 3	220
	11th to 20th	Day	38% 25% 29% 8%	220
	21st to end	Day	40% 22% 26% 11% 1	242
January	1st to 10th	Night	36% 23% 28% 11% 2	840
	11th to 20th	Night	35% 21% 27% 14% 3	840
	21st to end	Night	27% 23% 31% 17% 3	924
February	1st to 10th	Night	30% 23% 29% 16% 2	840
	11th to 20th	Night	29% 22% 34% 13% 2	823
	21st to end	Night	30% 19% 33% 15% 3	692
March	1st to 10th	Night	30% 18% 31% 19% 3	840
	11th to 20th	Night	31% 20% 27% 18% 4	840
	21st to end	Night	28% 17% 31% 18% 6%	924
April	1st to 10th	Night	30% 18% 28% 21% 3	840
	11th to 20th	Night	28% 18% 26% 21% 7%	831
	21st to end	Night	29% 13% 25% 23% 9%	803
May	1st to 10th	Night	30% 9% 24% 27% 9% 1	441
	11th to 20th	Night	18% 9% 31% 32% 9% 1	406
	21st to end	Night	16% 7% 26% 35% 16% 1	433
June	1st to 10th	Night	22% 8% 22% 37% 12% 1	400
	11th to 20th	Night	17% 9% 24% 33% 18% 1	400
	21st to end	Night	16% 7% 26% 40% 10% 1	400
July	1st to 10th	Night	12% 5% 19% 41% 23% 1	390
	11th to 20th	Night	12% 5% 24% 38% 19% 3	388
	21st to end	Night	14% 3 22% 44% 16% 1	438
August	1st to 10th	Night	13% 5% 22% 39% 20% 1	544
	11th to 20th	Night	15% 4 20% 33% 24% 3	624
	21st to end	Night	15% 7% 22% 37% 18% 1	880
September	1st to 10th	Night	18% 8% 20% 32% 18% 3	800
	11th to 20th	Night	16% 7% 20% 30% 22% 5%	800
	21st to end	Night	19% 11% 24% 28% 16% 3	800
October	1st to 10th	Night	28% 11% 22% 23% 14% 2	800
	11th to 20th	Night	29% 16% 28% 20% 7% 1	800
	21st to end	Night	36% 17% 27% 18% 2	880
November	1st to 10th	Night	32% 14% 28% 20% 6%	820
	11th to 20th	Night	33% 18% 28% 15% 5% 1	840
	21st to end	Night	38% 20% 26% 13% 3	840
December	1st to 10th	Night	38% 21% 27% 12% 2	840
	11th to 20th	Night	36% 21% 29% 11% 2	840
	21st to end	Night	38% 21% 26% 13% 2	924

Page generated at 2026-05-14 01:59:00. Version ac07

Copyright © 2026 Attilla Danko.