Wapiticrossing Ranch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wapiticrossing Ranch clear sky chart from 2005-11-06 to 2026-01-02.

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	7% 13% 4 9% 5% 4 4 3 5% 6% 39%	130912
	Night	6% 13% 5% 10% 5% 5% 5% 4 5% 6% 36%	129166
Transparency	Day	28% 37% 8% 15% 9% 3	130631
	Night	30% 37% 9% 14% 8% 2	129023
Seeing	Day	19% 16% 27% 22% 12% 4	16490
	Night	16% 11% 23% 31% 18% 2	25786

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	4 29% 15% 18% 6% 4 4 3 3 4 11%	3508
	11th to 20th	Day	6% 19% 7% 17% 6% 6% 4 3 3 5% 24%	3616
	21st to end	Day	7% 19% 5% 10% 5% 5% 4 3 4 5% 32%	4004
February	1st to 10th	Day	8% 27% 10% 15% 6% 4 4 3 4 4 15%	1629
	11th to 20th	Day	7% 29% 8% 13% 6% 4 4 3 4 5% 16%	1862
	21st to end	Day	7% 27% 10% 15% 7% 4 3 3 4 4 17%	1650
March	1st to 10th	Day	5% 15% 5% 12% 6% 4 4 3 7% 11% 26%	4518
	11th to 20th	Day	4 22% 7% 12% 7% 5% 3 3 3 4 31%	4859
	21st to end	Day	8% 26% 7% 15% 7% 5% 5% 4 5% 6% 12%	5678
April	1st to 10th	Day	11% 24% 6% 11% 6% 5% 5% 4 5% 5% 17%	2400
	11th to 20th	Day	10% 21% 5% 10% 6% 5% 5% 3 4 5% 26%	2517
	21st to end	Day	13% 18% 3 9% 6% 6% 6% 3 4 6% 25%	2600
May	1st to 10th	Day	10% 14% 3 7% 4 4 4 3 4 5% 40%	5918
	11th to 20th	Day	8% 13% 4 10% 6% 5% 6% 5% 6% 9% 28%	6277
	21st to end	Day	10% 10% 3 7% 6% 5% 6% 5% 6% 7% 36%	7305
June	1st to 10th	Day	18% 10% 3 8% 6% 6% 5% 4 5% 7% 29%	3000
	11th to 20th	Day	17% 9% 3 9% 6% 5% 5% 4 7% 6% 28%	3000
	21st to end	Day	7% 5% 2 6% 4 5% 4 5% 6% 7% 49%	3000
July	1st to 10th	Day	4 2 1 2 2 2 3 3 5% 6% 69%	6744
	11th to 20th	Day	4 2 1 2 2 2 2 2 3 4 76%	6320
	21st to end	Day	3 2 1 3 2 3 3 3 5% 8% 69%	6874
August	1st to 10th	Day	4 3 1 4 3 3 4 4 5% 8% 62%	4510
	11th to 20th	Day	4 4 2 4 3 3 4 3 5% 7% 61%	4158
	21st to end	Day	4 3 1 4 3 4 5% 3 5% 8% 60%	4573
September	1st to 10th	Day	6% 4 1 5% 3 3 4 4 5% 8% 58%	2400
	11th to 20th	Day	9% 8% 3 6% 5% 5% 5% 3 6% 7% 45%	2210
	21st to end	Day	9% 7% 3 7% 4 4 4 4 5% 8% 44%	2200
October	1st to 10th	Day	7% 7% 2 6% 4 3 3 3 4 7% 55%	3600
	11th to 20th	Day	8% 12% 3 8% 5% 4 5% 4 4 7% 39%	2983
	21st to end	Day	12% 17% 6% 10% 5% 5% 5% 3 4 5% 27%	3200
November	1st to 10th	Day	14% 26% 5% 9% 6% 4 4 3 5% 6% 19%	1854
	11th to 20th	Day	9% 25% 8% 12% 6% 5% 5% 2 5% 5% 18%	1806
	21st to end	Day	6% 24% 9% 11% 6% 6% 5% 3 5% 6% 19%	1492
December	1st to 10th	Day	5% 16% 10% 10% 4 4 4 4 4 7% 34%	2360
	11th to 20th	Day	6% 24% 10% 17% 8% 5% 5% 3 4 5% 12%	2712
	21st to end	Day	4 24% 11% 18% 6% 4 4 3 5% 6% 15%	3575
January	1st to 10th	Night	4 25% 12% 16% 7% 6% 6% 3 5% 5% 11%	6490
	11th to 20th	Night	5% 15% 8% 15% 7% 6% 5% 4 5% 7% 24%	6282
	21st to end	Night	6% 19% 5% 10% 6% 5% 5% 3 4 6% 30%	6952
February	1st to 10th	Night	8% 25% 7% 14% 7% 4 4 3 4 5% 19%	2770
	11th to 20th	Night	7% 23% 8% 13% 6% 5% 4 3 4 5% 23%	2423
	21st to end	Night	5% 19% 8% 15% 9% 6% 5% 4 4 5% 21%	1980
March	1st to 10th	Night	3 13% 5% 11% 6% 5% 5% 4 5% 8% 36%	5376
	11th to 20th	Night	4 14% 6% 14% 7% 5% 5% 3 4 4 34%	5139
	21st to end	Night	8% 18% 6% 15% 8% 6% 6% 5% 6% 7% 15%	5284
April	1st to 10th	Night	8% 14% 5% 9% 6% 5% 6% 5% 7% 7% 29%	2000
	11th to 20th	Night	8% 14% 3 9% 7% 7% 5% 3 5% 6% 33%	1832
	21st to end	Night	8% 11% 3 9% 5% 5% 6% 5% 7% 7% 35%	1800
May	1st to 10th	Night	8% 12% 2 6% 4 4 5% 4 6% 7% 42%	4057
	11th to 20th	Night	10% 7% 3 7% 5% 6% 6% 5% 8% 8% 35%	3616
	21st to end	Night	11% 9% 2 7% 5% 4 5% 4 6% 7% 42%	3570
June	1st to 10th	Night	13% 9% 3 8% 4 5% 4 4 7% 6% 38%	1400
	11th to 20th	Night	13% 7% 2 6% 5% 5% 4 4 6% 7% 40%	1400
	21st to end	Night	6% 5% 2 5% 4 4 5% 4 7% 6% 53%	1400
July	1st to 10th	Night	2 1 1 1 1 1 2 2 3 6% 79%	3212
	11th to 20th	Night	2 2 1 2 2 2 2 2 2 4 79%	3640
	21st to end	Night	1 3 1 4 2 2 3 3 5% 7% 69%	3969
August	1st to 10th	Night	3 3 1 4 2 3 3 3 5% 7% 66%	2641
	11th to 20th	Night	4 3 1 4 3 3 4 4 6% 8% 62%	2901
	21st to end	Night	3 3 1 3 2 3 4 3 4 6% 66%	3336
September	1st to 10th	Night	5% 3 1 4 3 3 4 3 5% 7% 62%	2000
	11th to 20th	Night	7% 6% 2 5% 4 4 5% 4 5% 7% 52%	2190
	21st to end	Night	9% 7% 2 5% 3 3 3 3 5% 7% 53%	2200
October	1st to 10th	Night	5% 7% 2 6% 4 4 5% 4 6% 6% 52%	3600
	11th to 20th	Night	7% 9% 3 6% 4 5% 5% 4 6% 7% 44%	4163
	21st to end	Night	8% 14% 4 10% 6% 5% 5% 3 5% 6% 35%	4600
November	1st to 10th	Night	12% 18% 5% 10% 6% 5% 5% 4 5% 7% 23%	2665
	11th to 20th	Night	9% 21% 6% 12% 6% 5% 4 3 5% 5% 22%	2791
	21st to end	Night	6% 18% 7% 11% 7% 7% 6% 3 5% 6% 23%	3124
December	1st to 10th	Night	4 15% 9% 10% 5% 4 4 4 5% 7% 33%	5040
	11th to 20th	Night	5% 19% 8% 18% 9% 6% 6% 4 5% 5% 14%	5700
	21st to end	Night	4 21% 10% 18% 7% 6% 5% 3 5% 5% 15%	7623

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	61% 26% 7% 5%	3508
	11th to 20th	Day	47% 26% 11% 13% 3	3640
	21st to end	Day	35% 28% 13% 18% 6%	4004
February	1st to 10th	Day	31% 61% 3 2 2	1629
	11th to 20th	Day	29% 61% 3 5% 2	1871
	21st to end	Day	26% 61% 1 8% 2 1	1650
March	1st to 10th	Day	31% 30% 9% 15% 15%	4518
	11th to 20th	Day	40% 27% 13% 19% 1	4860
	21st to end	Day	52% 29% 9% 8% 2	5678
April	1st to 10th	Day	25% 62% 7% 5% 1	2400
	11th to 20th	Day	21% 62% 4 10% 3	2517
	21st to end	Day	23% 61% 3 9% 3	2600
May	1st to 10th	Day	31% 29% 7% 20% 13%	5918
	11th to 20th	Day	37% 30% 12% 19% 3	6280
	21st to end	Day	28% 29% 14% 20% 7% 1	7306
June	1st to 10th	Day	14% 62% 7% 13% 5%	3000
	11th to 20th	Day	19% 62% 4 9% 6% 1	3000
	21st to end	Day	15% 60% 5% 12% 8% 1	3000
July	1st to 10th	Day	12% 25% 6% 14% 28% 15%	6670
	11th to 20th	Day	10% 24% 2 19% 17% 27%	6245
	21st to end	Day	12% 25% 5% 26% 21% 11%	6681
August	1st to 10th	Day	14% 36% 4 18% 22% 8%	4493
	11th to 20th	Day	17% 36% 6% 29% 12% 1	4197
	21st to end	Day	14% 36% 8% 24% 16% 2	4572
September	1st to 10th	Day	12% 57% 6% 16% 8% 3	2400
	11th to 20th	Day	19% 57% 6% 12% 6% 1	2210
	21st to end	Day	20% 58% 6% 11% 5% 1	2200
October	1st to 10th	Day	15% 35% 9% 27% 14%	3600
	11th to 20th	Day	26% 35% 15% 16% 7%	2983
	21st to end	Day	40% 35% 8% 13% 3 1	3200
November	1st to 10th	Day	33% 54% 7% 6% 1	1854
	11th to 20th	Day	30% 55% 8% 5% 3	1806
	21st to end	Day	29% 54% 7% 7% 3	1492
December	1st to 10th	Day	32% 35% 15% 17% 2	2360
	11th to 20th	Day	52% 30% 10% 7% 1	2714
	21st to end	Day	52% 25% 13% 7% 3	3575
January	1st to 10th	Night	59% 27% 8% 5% 1	6490
	11th to 20th	Night	43% 27% 12% 11% 6% 1	6320
	21st to end	Night	38% 28% 11% 16% 6%	6952
February	1st to 10th	Night	29% 62% 3 4 2	2770
	11th to 20th	Night	26% 61% 5% 6% 3	2424
	21st to end	Night	23% 62% 3 8% 3 1	1980
March	1st to 10th	Night	27% 31% 10% 16% 16% 1	5376
	11th to 20th	Night	37% 28% 12% 22% 2	5139
	21st to end	Night	48% 30% 10% 10% 2	5284
April	1st to 10th	Night	16% 62% 10% 9% 3	2000
	11th to 20th	Night	17% 62% 6% 10% 4 1	1832
	21st to end	Night	17% 63% 5% 11% 5%	1800
May	1st to 10th	Night	29% 28% 10% 18% 15%	4054
	11th to 20th	Night	33% 29% 12% 18% 8%	3616
	21st to end	Night	26% 29% 11% 26% 8%	3570
June	1st to 10th	Night	11% 62% 5% 16% 6% 1	1400
	11th to 20th	Night	14% 62% 4 11% 7% 2	1400
	21st to end	Night	12% 60% 6% 13% 8% 2	1400
July	1st to 10th	Night	7% 24% 6% 21% 26% 17%	3177
	11th to 20th	Night	8% 24% 3 20% 17% 28%	3592
	21st to end	Night	13% 24% 6% 23% 19% 15%	3857
August	1st to 10th	Night	13% 35% 3 16% 22% 10%	2633
	11th to 20th	Night	15% 35% 7% 30% 13% 1	2928
	21st to end	Night	12% 35% 7% 28% 15% 4	3336
September	1st to 10th	Night	11% 57% 6% 14% 9% 3	2000
	11th to 20th	Night	14% 57% 6% 14% 8% 1	2190
	21st to end	Night	15% 57% 8% 13% 7% 1	2200
October	1st to 10th	Night	19% 35% 7% 25% 13%	3600
	11th to 20th	Night	22% 36% 13% 15% 13%	4163
	21st to end	Night	32% 36% 10% 17% 5% 1	4600
November	1st to 10th	Night	30% 54% 8% 7% 1	2665
	11th to 20th	Night	27% 55% 7% 7% 3 1	2791
	21st to end	Night	25% 55% 7% 9% 5%	3124
December	1st to 10th	Night	30% 35% 17% 14% 4	5040
	11th to 20th	Night	49% 32% 11% 7% 1	5697
	21st to end	Night	52% 25% 13% 6% 3	7623

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	20% 20% 27% 22% 10% 1	202
	11th to 20th	Day	23% 20% 28% 14% 13% 3	200
	21st to end	Day	22% 21% 24% 22% 6% 4	220
February	1st to 10th	Day	28% 27% 27% 13% 3 1	215
	11th to 20th	Day	24% 21% 30% 19% 6%	407
	21st to end	Day	31% 17% 30% 16% 5% 1	414
March	1st to 10th	Day	26% 23% 25% 18% 7% 1	500
	11th to 20th	Day	26% 18% 26% 17% 11% 2	500
	21st to end	Day	32% 22% 26% 15% 4 1	550
April	1st to 10th	Day	28% 23% 27% 15% 6% 1	500
	11th to 20th	Day	27% 25% 28% 13% 5% 2	492
	21st to end	Day	26% 21% 26% 19% 5% 3	500
May	1st to 10th	Day	18% 20% 27% 23% 10% 2	503
	11th to 20th	Day	26% 14% 28% 17% 11% 4	528
	21st to end	Day	22% 13% 22% 21% 16% 6%	741
June	1st to 10th	Day	20% 13% 25% 21% 16% 5%	730
	11th to 20th	Day	22% 19% 26% 19% 11% 3	730
	21st to end	Day	9% 13% 25% 28% 20% 5%	730
July	1st to 10th	Day	5% 11% 28% 29% 20% 7%	711
	11th to 20th	Day	9% 13% 34% 28% 11% 5%	524
	21st to end	Day	6% 11% 35% 30% 13% 5%	575
August	1st to 10th	Day	8% 12% 30% 29% 15% 5%	527
	11th to 20th	Day	6% 8% 31% 31% 18% 6%	517
	21st to end	Day	9% 14% 28% 27% 16% 6%	583
September	1st to 10th	Day	7% 12% 31% 25% 17% 7%	530
	11th to 20th	Day	15% 15% 27% 24% 13% 5%	530
	21st to end	Day	18% 18% 25% 22% 13% 5%	530
October	1st to 10th	Day	18% 10% 31% 26% 11% 4	530
	11th to 20th	Day	24% 15% 22% 21% 13% 5%	335
	21st to end	Day	29% 15% 28% 18% 7% 3	363
November	1st to 10th	Day	32% 16% 19% 25% 8%	330
	11th to 20th	Day	24% 20% 26% 17% 10% 2	330
	21st to end	Day	18% 22% 26% 26% 8%	231
December	1st to 10th	Day	25% 20% 22% 18% 12% 3	220
	11th to 20th	Day	30% 20% 24% 20% 6%	220
	21st to end	Day	25% 19% 28% 19% 8% 2	242
January	1st to 10th	Night	19% 17% 26% 27% 10% 1	883
	11th to 20th	Night	17% 13% 30% 27% 11% 2	800
	21st to end	Night	15% 13% 30% 30% 10% 1	880
February	1st to 10th	Night	20% 18% 30% 22% 9% 1	800
	11th to 20th	Night	21% 14% 27% 28% 9% 1	784
	21st to end	Night	20% 15% 26% 25% 13% 2	660
March	1st to 10th	Night	15% 13% 27% 31% 14% 1	800
	11th to 20th	Night	17% 15% 22% 30% 15% 1	800
	21st to end	Night	19% 12% 26% 31% 11% 1	880
April	1st to 10th	Night	17% 14% 22% 30% 15% 2	800
	11th to 20th	Night	16% 14% 29% 27% 13% 1	644
	21st to end	Night	14% 13% 26% 30% 15% 2	600
May	1st to 10th	Night	14% 8% 23% 33% 20% 2	583
	11th to 20th	Night	13% 5% 21% 30% 27% 5%	394
	21st to end	Night	19% 8% 13% 27% 28% 5%	433
June	1st to 10th	Night	17% 7% 17% 30% 25% 5%	400
	11th to 20th	Night	19% 9% 20% 34% 17% 3	400
	21st to end	Night	8% 6% 13% 40% 32% 2	400
July	1st to 10th	Night	1 3 15% 39% 40% 2	390
	11th to 20th	Night	4 4 13% 50% 27% 2	388
	21st to end	Night	3 2 10% 45% 38% 2	438
August	1st to 10th	Night	4 4 11% 38% 40% 4	417
	11th to 20th	Night	4 2 13% 40% 34% 7%	594
	21st to end	Night	6% 4 16% 38% 33% 3	712
September	1st to 10th	Night	6% 3 16% 37% 32% 7%	800
	11th to 20th	Night	11% 5% 14% 33% 32% 6%	800
	21st to end	Night	13% 7% 15% 36% 24% 5%	800
October	1st to 10th	Night	12% 8% 18% 41% 21% 1	800
	11th to 20th	Night	18% 8% 17% 32% 21% 4	800
	21st to end	Night	20% 14% 21% 29% 14% 3	880
November	1st to 10th	Night	23% 12% 26% 29% 11%	820
	11th to 20th	Night	23% 17% 25% 24% 11% 1	901
	21st to end	Night	16% 15% 27% 28% 13% 1	1050
December	1st to 10th	Night	18% 16% 23% 29% 12% 1	1050
	11th to 20th	Night	21% 15% 31% 26% 8%	1050
	21st to end	Night	21% 18% 30% 22% 8%	1155

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