Steinbach
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Steinbach clear sky chart from 2005-11-06 to 2026-04-02.

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	11% 9% 4 9% 6% 5% 5% 4 6% 8% 34%	135135
	Night	9% 10% 4 10% 6% 5% 5% 4 6% 7% 32%	135497
Transparency	Day	47% 6% 15% 23% 8% 1	134833
	Night	50% 6% 13% 22% 9% 1	135382
Seeing	Day	15% 9% 32% 28% 13% 3	18087
	Night	15% 7% 32% 32% 12% 1	28198

By Month

Percentage Cloud Cover NW (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	5% 15% 7% 15% 8% 6% 8% 6% 6% 7% 18%	4125
	11th to 20th	Day	4 11% 6% 14% 10% 10% 10% 10% 9% 6% 11%	4119
	21st to end	Day	5% 12% 6% 15% 8% 8% 8% 4 7% 8% 17%	5165
February	1st to 10th	Day	7% 12% 6% 13% 9% 7% 8% 5% 8% 6% 18%	1839
	11th to 20th	Day	7% 10% 4 9% 6% 9% 9% 7% 8% 9% 24%	1844
	21st to end	Day	6% 11% 4 14% 9% 7% 8% 6% 5% 7% 23%	1622
March	1st to 10th	Day	8% 11% 4 10% 10% 6% 5% 4 6% 7% 29%	4766
	11th to 20th	Day	8% 10% 4 15% 11% 7% 5% 4 6% 7% 23%	5088
	21st to end	Day	11% 13% 6% 11% 7% 5% 5% 4 5% 6% 27%	5585
April	1st to 10th	Day	10% 12% 4 8% 6% 4 5% 4 5% 7% 34%	2434
	11th to 20th	Day	13% 10% 4 8% 6% 5% 5% 4 5% 8% 32%	2572
	21st to end	Day	17% 10% 3 8% 4 4 4 4 5% 7% 33%	2600
May	1st to 10th	Day	13% 8% 3 6% 4 3 4 4 5% 7% 45%	6122
	11th to 20th	Day	17% 9% 2 6% 5% 4 4 4 6% 8% 33%	6530
	21st to end	Day	14% 7% 3 6% 3 4 4 3 5% 6% 46%	7428
June	1st to 10th	Day	14% 7% 3 7% 5% 5% 4 4 6% 9% 36%	3000
	11th to 20th	Day	14% 8% 2 6% 5% 4 6% 4 6% 8% 37%	3000
	21st to end	Day	12% 7% 2 7% 6% 5% 6% 5% 7% 8% 35%	3000
July	1st to 10th	Day	8% 4 2 5% 4 5% 5% 5% 7% 9% 45%	6800
	11th to 20th	Day	10% 5% 2 6% 5% 5% 5% 4 6% 9% 44%	6800
	21st to end	Day	8% 5% 2 6% 4 5% 5% 4 7% 9% 45%	7342
August	1st to 10th	Day	8% 5% 2 6% 4 4 5% 5% 7% 9% 46%	4339
	11th to 20th	Day	11% 6% 2 5% 4 4 4 4 6% 8% 46%	4171
	21st to end	Day	13% 5% 2 5% 4 4 4 3 6% 9% 45%	4675
September	1st to 10th	Day	10% 5% 2 5% 3 4 4 3 6% 8% 48%	2482
	11th to 20th	Day	15% 7% 3 6% 5% 4 4 4 5% 9% 38%	2200
	21st to end	Day	15% 7% 2 5% 4 4 4 3 5% 9% 41%	2200
October	1st to 10th	Day	12% 7% 2 6% 4 4 5% 3 5% 6% 47%	3295
	11th to 20th	Day	12% 9% 3 8% 5% 3 4 3 6% 7% 40%	3220
	21st to end	Day	15% 12% 3 7% 5% 5% 5% 5% 5% 8% 32%	3190
November	1st to 10th	Day	14% 16% 5% 11% 6% 5% 4 3 5% 5% 27%	1662
	11th to 20th	Day	11% 15% 7% 14% 7% 4 4 3 4 5% 24%	1680
	21st to end	Day	13% 13% 6% 14% 9% 7% 5% 3 5% 5% 21%	1596
December	1st to 10th	Day	9% 16% 6% 15% 9% 8% 6% 5% 5% 6% 14%	2360
	11th to 20th	Day	8% 16% 6% 13% 6% 4 4 5% 8% 10% 19%	2709
	21st to end	Day	8% 14% 7% 20% 8% 7% 8% 5% 7% 5% 11%	3575
January	1st to 10th	Night	4 13% 7% 17% 9% 8% 8% 5% 6% 7% 16%	8799
	11th to 20th	Night	4 15% 6% 14% 9% 9% 10% 9% 7% 5% 12%	8809
	21st to end	Night	5% 14% 6% 12% 6% 5% 7% 6% 7% 8% 22%	9045
February	1st to 10th	Night	7% 14% 5% 12% 7% 7% 7% 6% 6% 6% 24%	2779
	11th to 20th	Night	6% 10% 3 8% 7% 7% 7% 6% 7% 8% 31%	2663
	21st to end	Night	6% 11% 5% 14% 8% 6% 6% 4 5% 6% 29%	2202
March	1st to 10th	Night	8% 11% 4 10% 7% 5% 5% 4 6% 6% 32%	5319
	11th to 20th	Night	6% 11% 4 10% 6% 5% 5% 4 6% 8% 35%	5090
	21st to end	Night	12% 12% 5% 12% 5% 4 3 4 5% 5% 33%	5588
April	1st to 10th	Night	10% 11% 2 7% 5% 5% 4 4 5% 7% 40%	1983
	11th to 20th	Night	13% 11% 4 8% 5% 4 4 3 5% 6% 36%	1779
	21st to end	Night	13% 9% 3 7% 5% 5% 5% 4 5% 6% 37%	1800
May	1st to 10th	Night	13% 7% 3 6% 4 3 4 3 5% 7% 44%	3857
	11th to 20th	Night	16% 8% 3 7% 5% 5% 4 3 6% 8% 37%	3384
	21st to end	Night	13% 7% 2 5% 3 3 3 3 5% 7% 49%	3470
June	1st to 10th	Night	12% 6% 3 5% 4 5% 5% 4 5% 8% 43%	1400
	11th to 20th	Night	12% 5% 2 6% 5% 4 4 3 6% 8% 44%	1400
	21st to end	Night	11% 4 3 5% 5% 5% 6% 3 7% 8% 43%	1400
July	1st to 10th	Night	7% 4 2 5% 4 4 4 5% 6% 9% 49%	3180
	11th to 20th	Night	7% 3 2 4 3 5% 4 4 7% 9% 52%	3180
	21st to end	Night	6% 4 2 5% 4 4 5% 5% 7% 10% 47%	3509
August	1st to 10th	Night	5% 5% 2 6% 4 4 5% 4 7% 10% 48%	2821
	11th to 20th	Night	11% 4 2 4 3 4 5% 3 6% 8% 50%	2888
	21st to end	Night	10% 5% 2 6% 4 4 4 4 5% 9% 47%	3234
September	1st to 10th	Night	10% 4 2 5% 4 3 4 4 5% 7% 53%	1914
	11th to 20th	Night	15% 5% 2 6% 4 4 4 4 6% 8% 44%	2200
	21st to end	Night	14% 7% 2 5% 4 4 4 4 5% 7% 43%	2200
October	1st to 10th	Night	15% 7% 3 6% 3 4 3 2 5% 7% 46%	3851
	11th to 20th	Night	12% 10% 3 7% 4 5% 4 3 4 6% 41%	3916
	21st to end	Night	11% 11% 4 8% 5% 4 4 3 5% 6% 37%	4610
November	1st to 10th	Night	13% 15% 5% 10% 6% 5% 4 3 5% 5% 29%	2855
	11th to 20th	Night	11% 17% 6% 12% 6% 5% 4 3 5% 5% 27%	2940
	21st to end	Night	11% 13% 5% 15% 8% 6% 5% 3 4 5% 23%	3019
December	1st to 10th	Night	8% 16% 6% 17% 14% 8% 6% 3 4 5% 13%	5050
	11th to 20th	Night	7% 15% 6% 15% 8% 5% 5% 5% 7% 7% 21%	5718
	21st to end	Night	8% 13% 6% 19% 9% 8% 6% 4 6% 5% 17%	7645

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	64% 5% 9% 16% 6%	4125
	11th to 20th	Day	68% 5% 10% 13% 5%	4140
	21st to end	Day	62% 5% 8% 19% 5%	5165
February	1st to 10th	Day	62% 5% 13% 12% 7%	1839
	11th to 20th	Day	52% 7% 14% 20% 7%	1853
	21st to end	Day	58% 6% 12% 15% 8%	1622
March	1st to 10th	Day	52% 7% 16% 15% 10%	4766
	11th to 20th	Day	58% 7% 13% 16% 6%	5090
	21st to end	Day	55% 7% 11% 21% 6%	5585
April	1st to 10th	Day	48% 6% 11% 24% 11% 1	2434
	11th to 20th	Day	49% 5% 12% 22% 10% 1	2572
	21st to end	Day	50% 5% 15% 21% 8% 2	2600
May	1st to 10th	Day	38% 5% 13% 25% 18%	6122
	11th to 20th	Day	47% 6% 11% 26% 10%	6534
	21st to end	Day	39% 6% 8% 25% 19% 4	7428
June	1st to 10th	Day	43% 7% 16% 24% 9%	3000
	11th to 20th	Day	44% 7% 15% 25% 9% 1	3000
	21st to end	Day	43% 9% 18% 23% 7%	3000
July	1st to 10th	Day	31% 9% 25% 28% 6%	6726
	11th to 20th	Day	35% 7% 22% 31% 5%	6719
	21st to end	Day	34% 8% 21% 31% 7%	7136
August	1st to 10th	Day	32% 9% 19% 30% 10%	4323
	11th to 20th	Day	35% 7% 20% 33% 5%	4210
	21st to end	Day	35% 6% 22% 30% 6%	4674
September	1st to 10th	Day	33% 6% 19% 32% 10% 1	2482
	11th to 20th	Day	42% 7% 21% 25% 5%	2200
	21st to end	Day	42% 5% 15% 31% 7%	2200
October	1st to 10th	Day	38% 5% 15% 29% 12%	3295
	11th to 20th	Day	42% 5% 13% 26% 15%	3220
	21st to end	Day	51% 5% 15% 24% 5%	3190
November	1st to 10th	Day	58% 6% 13% 18% 5% 1	1662
	11th to 20th	Day	61% 5% 15% 13% 5% 1	1680
	21st to end	Day	65% 6% 13% 13% 3	1596
December	1st to 10th	Day	69% 8% 10% 8% 5%	2360
	11th to 20th	Day	59% 5% 14% 15% 7%	2710
	21st to end	Day	71% 5% 7% 12% 4	3575
January	1st to 10th	Night	64% 7% 11% 12% 7%	8800
	11th to 20th	Night	68% 6% 8% 15% 4	8850
	21st to end	Night	57% 6% 11% 20% 6%	9045
February	1st to 10th	Night	57% 6% 13% 15% 8%	2779
	11th to 20th	Night	46% 7% 16% 21% 9%	2664
	21st to end	Night	55% 5% 11% 18% 10%	2202
March	1st to 10th	Night	49% 7% 15% 16% 10% 3	5319
	11th to 20th	Night	46% 6% 15% 22% 11%	5090
	21st to end	Night	52% 5% 9% 22% 11%	5588
April	1st to 10th	Night	43% 4 12% 23% 15% 2	1983
	11th to 20th	Night	49% 5% 8% 22% 15% 2	1779
	21st to end	Night	46% 6% 10% 26% 10% 2	1800
May	1st to 10th	Night	38% 5% 11% 26% 20%	3857
	11th to 20th	Night	44% 6% 10% 25% 14% 2	3384
	21st to end	Night	34% 5% 9% 25% 22% 5%	3470
June	1st to 10th	Night	37% 8% 16% 25% 14% 1	1400
	11th to 20th	Night	37% 8% 17% 25% 12% 2	1400
	21st to end	Night	37% 9% 20% 27% 7% 1	1400
July	1st to 10th	Night	28% 10% 24% 29% 8% 2	3145
	11th to 20th	Night	27% 6% 20% 38% 8%	3138
	21st to end	Night	28% 9% 25% 32% 6% 1	3411
August	1st to 10th	Night	28% 7% 17% 34% 13% 1	2813
	11th to 20th	Night	29% 7% 25% 30% 9%	2915
	21st to end	Night	33% 7% 19% 32% 9%	3234
September	1st to 10th	Night	30% 5% 16% 35% 13% 1	1914
	11th to 20th	Night	37% 7% 18% 27% 10% 1	2200
	21st to end	Night	39% 7% 12% 30% 11% 1	2200
October	1st to 10th	Night	39% 4 11% 34% 12% 1	3851
	11th to 20th	Night	43% 5% 12% 30% 10%	3916
	21st to end	Night	47% 5% 13% 28% 7%	4610
November	1st to 10th	Night	56% 6% 14% 17% 6% 1	2855
	11th to 20th	Night	58% 7% 15% 15% 5% 1	2940
	21st to end	Night	64% 6% 13% 13% 5%	3019
December	1st to 10th	Night	73% 6% 11% 8% 2	5050
	11th to 20th	Night	60% 6% 12% 12% 11%	5716
	21st to end	Night	67% 5% 9% 15% 4	7645

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% 9% 33% 31% 13% 2	330
	11th to 20th	Day	11% 7% 36% 32% 14% 1	330
	21st to end	Day	13% 10% 33% 28% 13% 3	363
February	1st to 10th	Day	14% 13% 34% 29% 9% 1	330
	11th to 20th	Day	10% 9% 36% 30% 12% 3	330
	21st to end	Day	10% 7% 45% 26% 10% 1	273
March	1st to 10th	Day	15% 7% 38% 29% 10% 1	330
	11th to 20th	Day	14% 13% 34% 27% 10% 2	330
	21st to end	Day	17% 11% 32% 27% 11% 2	363
April	1st to 10th	Day	15% 10% 36% 26% 10% 3	526
	11th to 20th	Day	18% 13% 33% 25% 11% 1	690
	21st to end	Day	21% 9% 32% 25% 11% 2	700
May	1st to 10th	Day	17% 11% 33% 25% 12% 2	703
	11th to 20th	Day	23% 8% 29% 26% 12% 2	725
	21st to end	Day	20% 8% 25% 29% 15% 3	789
June	1st to 10th	Day	15% 12% 27% 28% 14% 5%	730
	11th to 20th	Day	17% 10% 32% 29% 9% 2	730
	21st to end	Day	13% 9% 28% 30% 15% 5%	730
July	1st to 10th	Day	10% 6% 29% 28% 20% 8%	721
	11th to 20th	Day	12% 6% 30% 28% 18% 5%	718
	21st to end	Day	7% 5% 28% 34% 17% 8%	794
August	1st to 10th	Day	9% 5% 26% 33% 22% 5%	726
	11th to 20th	Day	12% 7% 25% 32% 16% 9%	715
	21st to end	Day	14% 8% 28% 29% 17% 4	803
September	1st to 10th	Day	11% 9% 33% 31% 13% 3	612
	11th to 20th	Day	14% 12% 39% 24% 8% 2	330
	21st to end	Day	21% 8% 37% 25% 9% 2	330
October	1st to 10th	Day	20% 11% 27% 30% 9% 3	330
	11th to 20th	Day	19% 10% 39% 23% 8%	330
	21st to end	Day	30% 10% 28% 23% 7% 1	363
November	1st to 10th	Day	25% 10% 32% 22% 10% 2	330
	11th to 20th	Day	18% 13% 38% 23% 7% 1	330
	21st to end	Day	18% 13% 38% 23% 7%	330
December	1st to 10th	Day	17% 6% 39% 26% 10% 2	330
	11th to 20th	Day	17% 11% 38% 26% 8%	330
	21st to end	Day	14% 7% 34% 28% 13% 4	363
January	1st to 10th	Night	11% 8% 36% 29% 14% 2	1050
	11th to 20th	Night	15% 7% 34% 33% 10% 1	1050
	21st to end	Night	13% 8% 37% 31% 10% 1	1155
February	1st to 10th	Night	14% 9% 29% 36% 12% 1	1050
	11th to 20th	Night	12% 6% 30% 36% 13% 3	1029
	21st to end	Night	11% 8% 36% 31% 13% 1	818
March	1st to 10th	Night	16% 9% 30% 31% 13% 2	769
	11th to 20th	Night	12% 7% 41% 28% 10% 1	630
	21st to end	Night	19% 8% 29% 29% 13% 3	693
April	1st to 10th	Night	14% 8% 32% 34% 11% 1	603
	11th to 20th	Night	19% 7% 32% 32% 10% 1	593
	21st to end	Night	17% 7% 29% 36% 11% 1	600
May	1st to 10th	Night	19% 6% 38% 27% 10% 1	600
	11th to 20th	Night	19% 6% 32% 30% 12% 1	591
	21st to end	Night	19% 7% 30% 33% 10% 1	650
June	1st to 10th	Night	16% 5% 29% 35% 14% 1	600
	11th to 20th	Night	15% 6% 31% 34% 14% 1	600
	21st to end	Night	12% 5% 24% 40% 18% 1	600
July	1st to 10th	Night	6% 4 25% 42% 22% 2	585
	11th to 20th	Night	9% 6% 25% 41% 18% 1	582
	21st to end	Night	9% 2 22% 44% 20% 3	657
August	1st to 10th	Night	8% 4 22% 46% 19% 1	597
	11th to 20th	Night	12% 3 22% 39% 21% 3	594
	21st to end	Night	13% 5% 26% 38% 18% 1	660
September	1st to 10th	Night	12% 5% 29% 37% 15% 2	600
	11th to 20th	Night	18% 6% 29% 36% 11%	600
	21st to end	Night	18% 6% 32% 32% 10% 1	600
October	1st to 10th	Night	21% 9% 35% 29% 7%	757
	11th to 20th	Night	20% 9% 34% 27% 8% 1	805
	21st to end	Night	23% 9% 30% 29% 8% 1	1100
November	1st to 10th	Night	20% 9% 36% 25% 9% 1	1025
	11th to 20th	Night	20% 9% 33% 27% 9% 2	1050
	21st to end	Night	17% 12% 39% 24% 6% 1	1050
December	1st to 10th	Night	13% 8% 35% 32% 11% 1	1050
	11th to 20th	Night	17% 10% 35% 30% 7% 1	1050
	21st to end	Night	19% 8% 33% 28% 10% 2	1155

Page generated at 2026-03-30 01:18:41. Version ac07

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