Malbie River
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Malbie River clear sky chart from 2005-11-06 to 2026-02-16.

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	16% 11% 4 8% 5% 5% 5% 4 5% 7% 31%	130907
	Night	16% 11% 4 9% 5% 4 4 3 5% 6% 33%	130155
Transparency	Day	32% 39% 10% 13% 5%	134360
	Night	34% 38% 8% 13% 6%	134794
Seeing	Day	21% 8% 27% 29% 13% 2	18299
	Night	23% 10% 27% 27% 12% 2	25915

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	9% 20% 7% 11% 5% 4 4 3 5% 7% 24%	4093
	11th to 20th	Day	11% 14% 6% 16% 4 5% 5% 4 6% 7% 21%	4084
	21st to end	Day	4 8% 5% 11% 6% 6% 5% 5% 6% 8% 37%	5289
February	1st to 10th	Day	8% 12% 4 10% 7% 5% 5% 5% 5% 6% 32%	1890
	11th to 20th	Day	10% 16% 5% 11% 7% 5% 4 3 6% 6% 28%	1798
	21st to end	Day	10% 12% 5% 10% 7% 5% 5% 4 6% 6% 32%	1485
March	1st to 10th	Day	17% 15% 5% 10% 5% 4 4 3 5% 6% 26%	4768
	11th to 20th	Day	15% 21% 5% 11% 5% 4 4 3 4 5% 22%	4980
	21st to end	Day	20% 18% 6% 9% 4 3 4 3 4 4 25%	5481
April	1st to 10th	Day	19% 13% 4 9% 6% 5% 5% 3 4 6% 27%	2400
	11th to 20th	Day	17% 12% 3 7% 5% 4 5% 4 6% 6% 31%	2551
	21st to end	Day	24% 13% 4 7% 4 3 4 3 4 6% 30%	2600
May	1st to 10th	Day	22% 14% 4 9% 5% 4 4 3 4 5% 26%	6293
	11th to 20th	Day	18% 11% 4 8% 4 4 4 3 5% 6% 32%	6318
	21st to end	Day	22% 11% 3 6% 4 4 4 3 5% 6% 32%	7256
June	1st to 10th	Day	22% 11% 3 7% 5% 4 4 4 4 6% 29%	3000
	11th to 20th	Day	18% 9% 3 6% 4 4 5% 4 5% 8% 34%	3000
	21st to end	Day	24% 11% 3 7% 5% 4 5% 4 5% 6% 25%	3000
July	1st to 10th	Day	13% 6% 2 7% 5% 5% 6% 5% 7% 9% 34%	6820
	11th to 20th	Day	11% 7% 3 7% 5% 5% 6% 5% 7% 8% 35%	6820
	21st to end	Day	13% 6% 2 6% 4 5% 5% 4 6% 8% 41%	7123
August	1st to 10th	Day	16% 6% 3 8% 6% 6% 6% 5% 7% 7% 31%	4349
	11th to 20th	Day	16% 6% 2 6% 5% 5% 5% 5% 6% 9% 35%	4175
	21st to end	Day	14% 5% 2 5% 4 4 4 3 5% 7% 46%	4614
September	1st to 10th	Day	18% 6% 2 6% 4 5% 4 3 5% 7% 39%	2400
	11th to 20th	Day	18% 7% 3 6% 4 4 3 3 5% 5% 43%	2323
	21st to end	Day	19% 7% 2 6% 4 4 4 3 4 6% 39%	2140
October	1st to 10th	Day	17% 6% 2 8% 5% 6% 5% 4 5% 6% 38%	2000
	11th to 20th	Day	21% 11% 3 7% 4 4 4 3 5% 6% 32%	2000
	21st to end	Day	22% 12% 3 7% 4 6% 4 3 5% 6% 29%	2047
November	1st to 10th	Day	17% 11% 3 9% 5% 6% 5% 4 5% 6% 30%	1645
	11th to 20th	Day	21% 10% 5% 9% 5% 5% 5% 5% 4 6% 25%	1680
	21st to end	Day	19% 15% 5% 9% 4 4 4 3 5% 6% 25%	1680
December	1st to 10th	Day	13% 14% 4 10% 4 4 5% 3 5% 4 32%	2564
	11th to 20th	Day	17% 13% 4 10% 6% 5% 4 3 5% 6% 29%	2688
	21st to end	Day	14% 12% 5% 13% 5% 4 4 2 4 6% 30%	3553
January	1st to 10th	Night	11% 18% 6% 13% 5% 5% 5% 3 5% 6% 22%	8831
	11th to 20th	Night	14% 12% 4 14% 5% 5% 5% 3 5% 6% 27%	8831
	21st to end	Night	4 9% 4 9% 5% 7% 4 4 5% 7% 43%	8897
February	1st to 10th	Night	8% 14% 4 9% 6% 5% 5% 3 5% 6% 35%	2730
	11th to 20th	Night	12% 15% 5% 10% 5% 4 5% 3 5% 5% 31%	2599
	21st to end	Night	11% 14% 4 8% 5% 5% 4 4 5% 6% 34%	2145
March	1st to 10th	Night	15% 14% 5% 9% 6% 5% 4 4 5% 6% 28%	5057
	11th to 20th	Night	18% 18% 4 10% 6% 5% 4 3 4 5% 22%	4979
	21st to end	Night	23% 14% 4 9% 5% 3 3 2 4 5% 26%	5450
April	1st to 10th	Night	21% 12% 4 9% 4 5% 4 3 4 5% 29%	2000
	11th to 20th	Night	19% 10% 3 8% 5% 4 3 4 4 6% 34%	1797
	21st to end	Night	23% 12% 3 6% 3 4 4 3 4 4 33%	1800
May	1st to 10th	Night	20% 14% 4 7% 4 4 4 3 4 5% 31%	3664
	11th to 20th	Night	19% 9% 3 7% 4 4 4 3 4 6% 37%	3596
	21st to end	Night	17% 10% 4 9% 5% 4 4 4 6% 6% 32%	3683
June	1st to 10th	Night	25% 8% 2 6% 4 4 5% 3 6% 7% 30%	1400
	11th to 20th	Night	18% 9% 2 6% 4 5% 4 4 4 6% 38%	1400
	21st to end	Night	22% 8% 3 6% 5% 5% 5% 5% 7% 5% 31%	1400
July	1st to 10th	Night	15% 7% 2 6% 4 4 5% 4 6% 9% 37%	3160
	11th to 20th	Night	12% 6% 2 6% 5% 4 6% 4 7% 8% 40%	3160
	21st to end	Night	10% 5% 2 6% 4 4 5% 4 5% 7% 48%	3692
August	1st to 10th	Night	15% 7% 2 8% 6% 5% 5% 4 5% 6% 36%	2800
	11th to 20th	Night	14% 6% 3 6% 4 4 5% 4 6% 7% 42%	2872
	21st to end	Night	14% 5% 2 5% 3 3 4 3 5% 7% 47%	3284
September	1st to 10th	Night	19% 6% 2 5% 3 4 4 3 4 5% 44%	2000
	11th to 20th	Night	17% 6% 2 5% 3 3 3 3 5% 6% 47%	2075
	21st to end	Night	18% 7% 2 5% 3 4 3 3 4 6% 45%	2260
October	1st to 10th	Night	18% 8% 2 6% 3 4 5% 3 5% 5% 41%	2400
	11th to 20th	Night	21% 10% 3 6% 4 4 4 3 4 5% 37%	2400
	21st to end	Night	21% 10% 2 7% 4 4 4 4 4 6% 33%	2791
November	1st to 10th	Night	20% 11% 3 7% 4 4 5% 3 5% 5% 33%	2873
	11th to 20th	Night	22% 12% 4 8% 4 3 4 3 6% 6% 28%	2940
	21st to end	Night	21% 14% 4 9% 5% 4 4 3 5% 5% 25%	2940
December	1st to 10th	Night	13% 12% 4 9% 5% 4 4 3 5% 5% 37%	4841
	11th to 20th	Night	18% 12% 4 7% 5% 4 4 3 5% 6% 32%	5741
	21st to end	Night	17% 13% 4 12% 6% 4 4 4 5% 6% 25%	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	49% 27% 13% 10% 2	4094
	11th to 20th	Day	47% 27% 12% 9% 5%	4110
	21st to end	Day	34% 27% 14% 13% 11%	5289
February	1st to 10th	Day	21% 60% 5% 8% 5% 1	1890
	11th to 20th	Day	21% 61% 5% 7% 6%	1806
	21st to end	Day	17% 62% 2 12% 5% 2	1485
March	1st to 10th	Day	42% 33% 10% 9% 5% 1	4772
	11th to 20th	Day	48% 33% 6% 8% 3 3	4980
	21st to end	Day	47% 31% 5% 12% 4 1	5481
April	1st to 10th	Day	22% 62% 4 7% 5% 1	2400
	11th to 20th	Day	19% 64% 4 8% 4 1	2551
	21st to end	Day	24% 63% 5% 5% 3	2600
May	1st to 10th	Day	38% 34% 9% 14% 5%	6305
	11th to 20th	Day	37% 31% 11% 17% 4	6322
	21st to end	Day	35% 32% 9% 18% 5%	7256
June	1st to 10th	Day	19% 64% 6% 8% 4	3000
	11th to 20th	Day	19% 63% 6% 9% 3 1	3000
	21st to end	Day	20% 62% 6% 8% 4	3000
July	1st to 10th	Day	32% 28% 13% 18% 9%	6745
	11th to 20th	Day	31% 30% 17% 18% 4	6739
	21st to end	Day	26% 28% 17% 20% 8%	6920
August	1st to 10th	Day	30% 40% 14% 13% 3	4335
	11th to 20th	Day	28% 39% 12% 15% 5% 1	4214
	21st to end	Day	20% 38% 12% 20% 10% 1	4614
September	1st to 10th	Day	16% 59% 8% 12% 5%	2400
	11th to 20th	Day	22% 58% 8% 10% 3	2323
	21st to end	Day	17% 58% 6% 13% 6% 1	2140
October	1st to 10th	Day	31% 37% 10% 18% 4 1	3260
	11th to 20th	Day	31% 39% 9% 17% 4	3240
	21st to end	Day	29% 37% 13% 14% 7%	3279
November	1st to 10th	Day	28% 55% 6% 8% 3 1	1645
	11th to 20th	Day	28% 57% 5% 6% 4	1680
	21st to end	Day	29% 55% 6% 6% 3	1680
December	1st to 10th	Day	35% 36% 6% 16% 6%	2564
	11th to 20th	Day	38% 32% 9% 12% 8% 1	2688
	21st to end	Day	42% 32% 12% 12% 2 1	3553
January	1st to 10th	Night	50% 28% 9% 11% 2	8831
	11th to 20th	Night	49% 25% 10% 10% 6%	8880
	21st to end	Night	33% 27% 11% 14% 13% 1	8897
February	1st to 10th	Night	20% 59% 5% 9% 5% 1	2730
	11th to 20th	Night	22% 60% 5% 8% 5%	2602
	21st to end	Night	18% 62% 4 9% 7% 1	2145
March	1st to 10th	Night	41% 32% 7% 11% 8% 1	5066
	11th to 20th	Night	51% 32% 6% 6% 4 1	4980
	21st to end	Night	48% 30% 5% 11% 6% 1	5450
April	1st to 10th	Night	21% 62% 3 5% 7% 1	2000
	11th to 20th	Night	20% 63% 4 8% 4 1	1797
	21st to end	Night	25% 63% 3 6% 3 1	1800
May	1st to 10th	Night	40% 33% 8% 13% 5% 2	3669
	11th to 20th	Night	35% 31% 7% 18% 8%	3597
	21st to end	Night	35% 33% 9% 15% 8%	3684
June	1st to 10th	Night	20% 64% 4 9% 4	1400
	11th to 20th	Night	19% 63% 4 8% 7%	1400
	21st to end	Night	20% 62% 5% 10% 4	1400
July	1st to 10th	Night	34% 29% 11% 16% 9%	3125
	11th to 20th	Night	31% 29% 16% 22% 2	3118
	21st to end	Night	26% 29% 17% 20% 8%	3582
August	1st to 10th	Night	35% 39% 9% 13% 4	2789
	11th to 20th	Night	25% 39% 13% 17% 6%	2899
	21st to end	Night	21% 38% 11% 20% 10%	3283
September	1st to 10th	Night	17% 58% 7% 14% 4	2000
	11th to 20th	Night	20% 58% 8% 11% 3	2075
	21st to end	Night	16% 58% 5% 14% 7%	2260
October	1st to 10th	Night	33% 37% 8% 18% 4	3920
	11th to 20th	Night	26% 37% 7% 22% 8%	3899
	21st to end	Night	33% 39% 9% 13% 6%	4513
November	1st to 10th	Night	26% 54% 6% 9% 4	2873
	11th to 20th	Night	28% 56% 6% 7% 3 1	2940
	21st to end	Night	29% 56% 7% 5% 3	2940
December	1st to 10th	Night	34% 37% 7% 16% 6%	4841
	11th to 20th	Night	36% 34% 8% 14% 7% 1	5742
	21st to end	Night	46% 30% 12% 10% 2	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	27% 17% 23% 27% 5% 1	220
	11th to 20th	Day	28% 15% 25% 20% 7% 4	220
	21st to end	Day	13% 10% 39% 27% 10% 1	386
February	1st to 10th	Day	16% 11% 38% 23% 10% 2	430
	11th to 20th	Day	17% 12% 37% 24% 8% 2	411
	21st to end	Day	15% 9% 35% 27% 11% 2	331
March	1st to 10th	Day	20% 10% 34% 27% 8% 2	480
	11th to 20th	Day	19% 11% 29% 28% 12% 2	500
	21st to end	Day	24% 14% 29% 25% 7% 1	550
April	1st to 10th	Day	25% 12% 30% 25% 7%	500
	11th to 20th	Day	22% 10% 33% 25% 8% 2	492
	21st to end	Day	27% 10% 23% 25% 13% 2	500
May	1st to 10th	Day	27% 7% 23% 29% 11% 2	677
	11th to 20th	Day	22% 7% 23% 29% 15% 4	724
	21st to end	Day	23% 9% 28% 28% 11% 1	790
June	1st to 10th	Day	26% 7% 24% 29% 12% 2	730
	11th to 20th	Day	21% 5% 22% 33% 16% 3	730
	21st to end	Day	24% 4 25% 32% 13% 1	730
July	1st to 10th	Day	17% 3 21% 40% 17% 2	720
	11th to 20th	Day	14% 4 21% 40% 19% 2	718
	21st to end	Day	18% 4 19% 36% 19% 4	795
August	1st to 10th	Day	13% 3 18% 35% 28% 2	601
	11th to 20th	Day	13% 3 18% 37% 24% 4	519
	21st to end	Day	14% 5% 23% 35% 19% 4	583
September	1st to 10th	Day	19% 5% 29% 30% 14% 3	530
	11th to 20th	Day	24% 5% 24% 30% 14% 3	530
	21st to end	Day	20% 8% 30% 28% 10% 3	497
October	1st to 10th	Day	17% 8% 30% 29% 13% 3	420
	11th to 20th	Day	28% 8% 29% 19% 13% 2	420
	21st to end	Day	27% 12% 27% 25% 7% 2	462
November	1st to 10th	Day	25% 14% 27% 25% 7% 1	425
	11th to 20th	Day	27% 15% 27% 22% 7% 2	430
	21st to end	Day	30% 13% 29% 24% 3 1	430
December	1st to 10th	Day	23% 12% 34% 25% 5% 1	356
	11th to 20th	Day	21% 20% 34% 19% 5% 1	220
	21st to end	Day	21% 20% 28% 22% 8% 1	242
January	1st to 10th	Night	25% 14% 32% 22% 7% 1	950
	11th to 20th	Night	23% 13% 33% 22% 8% 1	950
	21st to end	Night	16% 12% 37% 26% 9% 1	971
February	1st to 10th	Night	17% 11% 34% 28% 9% 1	840
	11th to 20th	Night	22% 11% 33% 26% 7% 1	804
	21st to end	Night	18% 11% 30% 27% 10% 3	660
March	1st to 10th	Night	20% 10% 33% 26% 9% 1	800
	11th to 20th	Night	22% 10% 31% 27% 9% 2	800
	21st to end	Night	23% 12% 28% 27% 9% 1	876
April	1st to 10th	Night	29% 9% 28% 27% 8% 1	600
	11th to 20th	Night	25% 7% 27% 28% 12% 1	594
	21st to end	Night	28% 7% 22% 29% 11% 3	600
May	1st to 10th	Night	25% 7% 19% 30% 17% 2	600
	11th to 20th	Night	23% 6% 19% 30% 19% 3	592
	21st to end	Night	22% 6% 24% 35% 11% 2	540
June	1st to 10th	Night	29% 4 19% 31% 16% 1	400
	11th to 20th	Night	23% 2 18% 37% 18% 3	400
	21st to end	Night	24% 5% 16% 35% 19% 3	400
July	1st to 10th	Night	18% 4 13% 39% 23% 3	390
	11th to 20th	Night	15% 4 16% 39% 24% 2	388
	21st to end	Night	18% 3 15% 39% 23% 1	543
August	1st to 10th	Night	17% 2 11% 38% 27% 3	598
	11th to 20th	Night	17% 2 13% 36% 30% 3	592
	21st to end	Night	16% 5% 18% 32% 25% 4	660
September	1st to 10th	Night	21% 6% 24% 31% 16% 2	600
	11th to 20th	Night	19% 8% 21% 34% 17% 2	675
	21st to end	Night	21% 7% 27% 30% 13% 2	800
October	1st to 10th	Night	22% 8% 28% 29% 12% 1	800
	11th to 20th	Night	25% 10% 27% 25% 12% 2	800
	21st to end	Night	26% 11% 29% 24% 10%	917
November	1st to 10th	Night	26% 13% 31% 23% 6% 1	930
	11th to 20th	Night	29% 14% 29% 19% 6% 2	950
	21st to end	Night	29% 14% 29% 22% 4 1	950
December	1st to 10th	Night	26% 16% 34% 18% 6%	950
	11th to 20th	Night	25% 21% 34% 15% 4 1	950
	21st to end	Night	28% 15% 29% 20% 7% 1	1045

Page generated at 2026-02-13 01:42:12. Version ac07

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