Waiparous Valley Viewpoint
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Waiparous Valley Viewpoint clear sky chart from 2005-11-06 to 2025-09-19.

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	7% 9% 3 9% 5% 5% 5% 4 6% 8% 37%	130677
	Night	5% 9% 3 8% 5% 5% 5% 4 7% 8% 41%	127086
Transparency	Day	42% 8% 15% 22% 11% 2	130384
	Night	39% 8% 16% 23% 12% 2	126956
Seeing	Day	16% 17% 32% 23% 10% 2	16463
	Night	11% 14% 36% 27% 11% 1	25387

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 3 13% 7% 7% 7% 5% 7% 8% 38%	3179
	11th to 20th	Day	1 6% 4 10% 7% 8% 6% 5% 7% 8% 38%	3315
	21st to end	Day	1 4 2 8% 5% 4 5% 4 7% 11% 48%	4004
February	1st to 10th	Day	1 6% 3 10% 7% 9% 8% 6% 7% 8% 35%	1600
	11th to 20th	Day	1 7% 5% 11% 6% 6% 7% 6% 8% 9% 35%	1691
	21st to end	Day	1 8% 6% 15% 7% 5% 5% 4 7% 8% 33%	1645
March	1st to 10th	Day	1 8% 3 9% 6% 4 4 4 6% 12% 43%	4518
	11th to 20th	Day	2 8% 4 10% 5% 4 5% 4 6% 8% 42%	4860
	21st to end	Day	3 16% 8% 17% 5% 4 4 4 6% 7% 25%	5693
April	1st to 10th	Day	5% 16% 5% 11% 6% 6% 5% 4 6% 7% 29%	2420
	11th to 20th	Day	7% 18% 6% 12% 5% 4 4 3 6% 8% 27%	2570
	21st to end	Day	9% 19% 5% 9% 5% 5% 4 4 5% 6% 30%	2600
May	1st to 10th	Day	10% 17% 4 7% 4 3 4 3 5% 6% 38%	6250
	11th to 20th	Day	11% 13% 4 10% 6% 5% 6% 5% 7% 8% 25%	6734
	21st to end	Day	13% 11% 3 8% 6% 5% 5% 4 5% 7% 34%	7405
June	1st to 10th	Day	18% 11% 3 8% 6% 4 5% 5% 6% 7% 26%	3000
	11th to 20th	Day	23% 11% 3 8% 6% 5% 6% 4 5% 7% 22%	3000
	21st to end	Day	13% 7% 3 8% 6% 6% 6% 4 6% 8% 33%	3000
July	1st to 10th	Day	8% 6% 2 7% 5% 6% 7% 6% 7% 8% 38%	6780
	11th to 20th	Day	12% 5% 2 6% 5% 5% 6% 6% 7% 8% 38%	6780
	21st to end	Day	10% 7% 2 6% 4 4 5% 4 7% 8% 43%	7110
August	1st to 10th	Day	12% 6% 3 7% 5% 5% 5% 5% 7% 7% 37%	4541
	11th to 20th	Day	10% 5% 2 7% 6% 5% 6% 5% 8% 8% 37%	4284
	21st to end	Day	9% 6% 2 6% 4 4 4 3 6% 8% 47%	4664
September	1st to 10th	Day	12% 7% 2 6% 3 4 4 4 5% 6% 44%	2447
	11th to 20th	Day	12% 9% 2 6% 4 4 4 3 5% 6% 45%	2204
	21st to end	Day	9% 8% 3 4 4 5% 6% 4 8% 8% 42%	2090
October	1st to 10th	Day	6% 8% 2 7% 4 4 4 4 6% 8% 46%	3386
	11th to 20th	Day	5% 9% 3 6% 5% 4 5% 4 6% 9% 44%	2842
	21st to end	Day	3 9% 4 6% 5% 6% 5% 4 5% 7% 47%	3101
November	1st to 10th	Day	3 11% 5% 8% 7% 5% 6% 5% 6% 7% 36%	1674
	11th to 20th	Day	2 9% 4 7% 5% 5% 5% 5% 6% 8% 45%	1460
	21st to end	Day	2 9% 4 11% 6% 5% 5% 4 6% 9% 40%	1400
December	1st to 10th	Day	2 6% 3 9% 6% 6% 7% 6% 8% 12% 36%	2290
	11th to 20th	Day	1 7% 3 9% 6% 6% 7% 5% 7% 10% 38%	2642
	21st to end	Day	1 8% 5% 11% 6% 4 4 4 5% 7% 45%	3498
January	1st to 10th	Night	1 7% 6% 13% 7% 8% 7% 5% 8% 9% 29%	6766
	11th to 20th	Night	1 6% 3 10% 7% 7% 7% 4 8% 9% 38%	6629
	21st to end	Night	1 7% 4 9% 6% 6% 5% 4 7% 9% 43%	6952
February	1st to 10th	Night	1 7% 3 10% 7% 6% 7% 5% 8% 10% 36%	2800
	11th to 20th	Night	1 9% 4 10% 7% 7% 7% 5% 7% 9% 34%	2596
	21st to end	Night	1 7% 4 12% 7% 7% 6% 5% 6% 8% 37%	1981
March	1st to 10th	Night	1 8% 3 10% 7% 6% 5% 5% 7% 10% 39%	5376
	11th to 20th	Night	2 7% 3 9% 6% 5% 5% 4 8% 10% 41%	5138
	21st to end	Night	3 15% 7% 14% 7% 5% 5% 3 6% 8% 27%	5280
April	1st to 10th	Night	4 12% 5% 10% 7% 5% 4 5% 6% 7% 34%	1979
	11th to 20th	Night	5% 13% 7% 11% 6% 5% 5% 4 6% 7% 32%	1781
	21st to end	Night	7% 14% 4 9% 4 5% 4 4 6% 7% 34%	1800
May	1st to 10th	Night	9% 16% 3 7% 4 4 3 3 4 6% 41%	3698
	11th to 20th	Night	9% 13% 5% 9% 5% 5% 5% 4 6% 8% 31%	3159
	21st to end	Night	10% 8% 2 7% 5% 4 4 3 5% 7% 44%	3470
June	1st to 10th	Night	17% 10% 3 6% 4 4 5% 4 6% 7% 35%	1400
	11th to 20th	Night	20% 9% 3 6% 5% 5% 5% 3 6% 7% 31%	1400
	21st to end	Night	10% 5% 2 6% 5% 5% 4 5% 7% 8% 44%	1400
July	1st to 10th	Night	8% 7% 2 6% 4 4 5% 4 6% 6% 47%	3180
	11th to 20th	Night	11% 5% 1 4 3 3 4 3 6% 7% 52%	3180
	21st to end	Night	10% 6% 2 5% 3 3 4 3 4 7% 52%	3730
August	1st to 10th	Night	13% 6% 2 5% 4 4 4 3 7% 10% 42%	2609
	11th to 20th	Night	9% 6% 2 5% 4 4 4 4 7% 11% 45%	2769
	21st to end	Night	9% 5% 2 4 4 3 4 3 5% 8% 53%	3245
September	1st to 10th	Night	10% 8% 2 4 3 3 4 3 5% 7% 51%	1950
	11th to 20th	Night	11% 10% 3 6% 4 3 4 3 5% 7% 45%	2153
	21st to end	Night	7% 9% 2 5% 4 4 4 3 5% 7% 49%	2090
October	1st to 10th	Night	5% 8% 2 5% 4 3 4 3 6% 7% 51%	3590
	11th to 20th	Night	4 7% 2 5% 3 4 5% 4 7% 9% 50%	4086
	21st to end	Night	3 10% 3 7% 4 4 5% 4 6% 8% 48%	4457
November	1st to 10th	Night	3 11% 5% 9% 5% 5% 5% 5% 7% 8% 37%	2605
	11th to 20th	Night	2 8% 2 8% 5% 5% 5% 4 7% 10% 44%	2939
	21st to end	Night	2 8% 4 10% 7% 4 5% 4 7% 9% 40%	3000
December	1st to 10th	Night	1 6% 4 10% 6% 5% 5% 5% 8% 10% 40%	4890
	11th to 20th	Night	1 8% 4 9% 7% 7% 7% 6% 8% 9% 34%	5550
	21st to end	Night	2 11% 4 10% 6% 5% 5% 4 6% 8% 39%	7458

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	41% 6% 14% 23% 13% 3	3179
	11th to 20th	Day	40% 8% 14% 17% 17% 4	3336
	21st to end	Day	27% 9% 20% 29% 15% 1	4004
February	1st to 10th	Day	42% 11% 13% 20% 10% 4	1600
	11th to 20th	Day	42% 11% 14% 21% 11% 2	1700
	21st to end	Day	46% 8% 14% 17% 13% 2	1645
March	1st to 10th	Day	35% 7% 16% 21% 20% 1	4518
	11th to 20th	Day	37% 7% 17% 22% 16% 1	4861
	21st to end	Day	56% 9% 12% 14% 8% 1	5693
April	1st to 10th	Day	53% 9% 16% 14% 8%	2420
	11th to 20th	Day	54% 9% 13% 15% 8% 1	2570
	21st to end	Day	54% 7% 14% 17% 6% 1	2600
May	1st to 10th	Day	46% 6% 11% 24% 12% 1	6250
	11th to 20th	Day	51% 10% 14% 19% 6%	6738
	21st to end	Day	48% 8% 14% 21% 9%	7406
June	1st to 10th	Day	53% 9% 14% 15% 8% 1	3000
	11th to 20th	Day	60% 8% 13% 11% 7% 1	3000
	21st to end	Day	45% 10% 16% 20% 9% 1	3000
July	1st to 10th	Day	38% 9% 14% 18% 17% 4	6706
	11th to 20th	Day	40% 8% 16% 26% 9% 2	6699
	21st to end	Day	37% 7% 13% 23% 16% 4	6910
August	1st to 10th	Day	42% 8% 13% 28% 8% 1	4524
	11th to 20th	Day	38% 10% 21% 23% 7% 1	4326
	21st to end	Day	33% 7% 19% 29% 10% 2	4663
September	1st to 10th	Day	37% 7% 16% 24% 12% 3	2447
	11th to 20th	Day	39% 7% 15% 25% 12% 2	2204
	21st to end	Day	37% 9% 18% 23% 11% 3	2090
October	1st to 10th	Day	34% 7% 17% 33% 9% 1	3386
	11th to 20th	Day	35% 8% 21% 21% 12% 3	2842
	21st to end	Day	36% 5% 12% 31% 13% 1	3101
November	1st to 10th	Day	44% 11% 14% 20% 11% 1	1674
	11th to 20th	Day	35% 10% 21% 22% 11% 2	1460
	21st to end	Day	39% 9% 19% 23% 7% 4	1400
December	1st to 10th	Day	39% 9% 21% 21% 9% 1	2290
	11th to 20th	Day	39% 10% 18% 23% 9% 1	2644
	21st to end	Day	37% 6% 10% 24% 18% 5%	3498
January	1st to 10th	Night	48% 10% 14% 19% 8% 2	6766
	11th to 20th	Night	42% 7% 13% 18% 14% 6%	6670
	21st to end	Night	35% 8% 18% 23% 14% 1	6952
February	1st to 10th	Night	42% 10% 15% 19% 12% 3	2800
	11th to 20th	Night	44% 9% 17% 18% 11% 2	2597
	21st to end	Night	44% 6% 12% 23% 13% 2	1981
March	1st to 10th	Night	39% 7% 17% 19% 15% 3	5376
	11th to 20th	Night	35% 8% 17% 23% 16% 1	5138
	21st to end	Night	54% 7% 13% 16% 9% 1	5280
April	1st to 10th	Night	47% 8% 15% 18% 11% 1	1979
	11th to 20th	Night	49% 6% 15% 19% 9% 1	1781
	21st to end	Night	46% 10% 15% 21% 7% 2	1800
May	1st to 10th	Night	44% 6% 12% 23% 14% 1	3695
	11th to 20th	Night	47% 8% 14% 26% 5%	3159
	21st to end	Night	38% 7% 15% 29% 10% 1	3470
June	1st to 10th	Night	45% 9% 14% 21% 10% 1	1400
	11th to 20th	Night	51% 9% 14% 16% 9% 2	1400
	21st to end	Night	34% 12% 18% 26% 8% 2	1400
July	1st to 10th	Night	36% 7% 14% 27% 13% 5%	3145
	11th to 20th	Night	31% 6% 21% 28% 10% 4	3138
	21st to end	Night	32% 5% 19% 27% 15% 2	3625
August	1st to 10th	Night	36% 7% 15% 31% 10%	2601
	11th to 20th	Night	30% 8% 28% 27% 6%	2793
	21st to end	Night	29% 5% 23% 31% 12% 1	3245
September	1st to 10th	Night	32% 6% 19% 27% 13% 3	1950
	11th to 20th	Night	39% 6% 15% 25% 12% 4	2153
	21st to end	Night	34% 6% 18% 27% 13% 2	2090
October	1st to 10th	Night	32% 7% 16% 27% 15% 3	3590
	11th to 20th	Night	30% 7% 18% 31% 12% 1	4086
	21st to end	Night	35% 6% 14% 32% 13%	4457
November	1st to 10th	Night	42% 9% 15% 22% 11% 2	2605
	11th to 20th	Night	34% 10% 19% 23% 13% 1	2939
	21st to end	Night	38% 8% 19% 22% 9% 4	3000
December	1st to 10th	Night	38% 8% 22% 22% 8% 2	4890
	11th to 20th	Night	42% 12% 18% 17% 11% 1	5547
	21st to end	Night	39% 8% 12% 21% 15% 4	7458

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	9% 14% 37% 26% 10% 5%	200
	11th to 20th	Day	6% 16% 44% 26% 8% 2	200
	21st to end	Day	9% 22% 41% 18% 8% 2	220
February	1st to 10th	Day	13% 20% 39% 20% 6% 4	200
	11th to 20th	Day	9% 19% 39% 27% 6%	267
	21st to end	Day	11% 24% 33% 23% 8% 1	409
March	1st to 10th	Day	13% 23% 36% 19% 7% 2	500
	11th to 20th	Day	10% 24% 37% 20% 5% 2	500
	21st to end	Day	15% 26% 31% 18% 7% 2	550
April	1st to 10th	Day	18% 23% 36% 18% 5% 1	500
	11th to 20th	Day	19% 22% 32% 19% 7% 1	492
	21st to end	Day	19% 23% 31% 16% 9% 2	500
May	1st to 10th	Day	19% 21% 27% 23% 8% 1	508
	11th to 20th	Day	19% 13% 24% 29% 13% 2	725
	21st to end	Day	23% 12% 22% 28% 12% 2	789
June	1st to 10th	Day	21% 15% 32% 21% 9% 1	730
	11th to 20th	Day	26% 16% 26% 21% 9% 2	730
	21st to end	Day	16% 12% 28% 27% 14% 3	730
July	1st to 10th	Day	13% 10% 30% 27% 17% 3	721
	11th to 20th	Day	15% 13% 28% 29% 13% 2	718
	21st to end	Day	11% 14% 30% 29% 14% 3	681
August	1st to 10th	Day	12% 12% 31% 31% 10% 3	527
	11th to 20th	Day	10% 12% 37% 27% 11% 3	517
	21st to end	Day	13% 14% 33% 26% 12% 2	583
September	1st to 10th	Day	17% 16% 32% 21% 11% 3	530
	11th to 20th	Day	18% 14% 28% 30% 7% 2	523
	21st to end	Day	19% 25% 28% 20% 6% 1	490
October	1st to 10th	Day	17% 17% 32% 21% 10% 3	443
	11th to 20th	Day	15% 19% 33% 22% 10% 1	300
	21st to end	Day	16% 22% 37% 18% 6% 2	330
November	1st to 10th	Day	13% 22% 39% 19% 5% 1	300
	11th to 20th	Day	17% 22% 42% 15% 4	230
	21st to end	Day	12% 21% 37% 17% 10% 4	200
December	1st to 10th	Day	9% 17% 44% 22% 8% 2	200
	11th to 20th	Day	11% 22% 41% 20% 6% 2	200
	21st to end	Day	9% 13% 37% 29% 9% 3	220
January	1st to 10th	Night	10% 18% 44% 21% 7% 1	1000
	11th to 20th	Night	8% 18% 46% 22% 5% 1	955
	21st to end	Night	11% 19% 42% 21% 7%	880
February	1st to 10th	Night	7% 17% 38% 25% 11% 3	800
	11th to 20th	Night	7% 16% 41% 27% 9% 1	784
	21st to end	Night	5% 16% 39% 26% 12% 2	660
March	1st to 10th	Night	5% 18% 41% 25% 10% 1	800
	11th to 20th	Night	7% 16% 43% 26% 8% 1	800
	21st to end	Night	8% 13% 37% 30% 10% 2	880
April	1st to 10th	Night	12% 12% 37% 27% 10% 1	779
	11th to 20th	Night	12% 15% 38% 26% 9%	593
	21st to end	Night	16% 14% 32% 29% 9%	600
May	1st to 10th	Night	17% 12% 24% 35% 11% 1	437
	11th to 20th	Night	11% 7% 31% 33% 17% 1	394
	21st to end	Night	20% 8% 22% 31% 18% 1	433
June	1st to 10th	Night	21% 9% 29% 28% 12% 2	400
	11th to 20th	Night	23% 9% 27% 28% 13% 1	400
	21st to end	Night	11% 8% 21% 35% 23% 2	400
July	1st to 10th	Night	12% 4 21% 42% 22%	390
	11th to 20th	Night	14% 5% 27% 36% 17% 2	388
	21st to end	Night	9% 6% 21% 40% 22% 3	438
August	1st to 10th	Night	11% 3 16% 37% 31% 2	398
	11th to 20th	Night	12% 5% 20% 40% 22% 2	510
	21st to end	Night	11% 6% 26% 40% 16% 1	660
September	1st to 10th	Night	15% 7% 25% 33% 16% 4	750
	11th to 20th	Night	17% 8% 23% 33% 16% 3	792
	21st to end	Night	13% 14% 34% 28% 10% 2	760
October	1st to 10th	Night	13% 11% 35% 29% 11% 1	760
	11th to 20th	Night	11% 13% 39% 28% 9% 1	760
	21st to end	Night	12% 16% 41% 26% 5% 1	836
November	1st to 10th	Night	11% 18% 44% 20% 6% 1	850
	11th to 20th	Night	11% 22% 43% 20% 3 1	1000
	21st to end	Night	8% 20% 43% 22% 6% 1	1000
December	1st to 10th	Night	8% 17% 43% 23% 8% 1	1000
	11th to 20th	Night	7% 17% 44% 24% 7% 1	1000
	21st to end	Night	6% 17% 42% 23% 9% 2	1100

Page generated at 2025-09-15 23:49:13. Version ac07

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