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 2024-12-02.

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	17% 10% 3 8% 5% 5% 5% 4 5% 7% 31%	102040
	Night	17% 11% 3 8% 5% 5% 4 3 5% 6% 33%	97715
Transparency	Day	26% 49% 9% 11% 4	105515
	Night	27% 49% 8% 11% 5%	102333
Seeing	Day	21% 8% 27% 29% 12% 2	16771
	Night	23% 10% 27% 27% 12% 1	24242

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	11% 14% 4 10% 5% 4 5% 3 6% 8% 29%	2207
	11th to 20th	Day	10% 11% 5% 10% 5% 5% 5% 5% 8% 10% 27%	2210
	21st to end	Day	7% 8% 4 11% 6% 7% 5% 5% 6% 8% 34%	2848
February	1st to 10th	Day	9% 13% 4 10% 6% 5% 5% 5% 5% 6% 32%	1710
	11th to 20th	Day	10% 17% 5% 10% 7% 5% 4 3 6% 6% 27%	1663
	21st to end	Day	10% 12% 5% 9% 7% 5% 5% 4 6% 6% 32%	1413
March	1st to 10th	Day	15% 13% 4 8% 5% 4 5% 4 5% 6% 30%	3324
	11th to 20th	Day	17% 23% 6% 11% 5% 4 4 3 4 4 19%	3480
	21st to end	Day	22% 15% 4 8% 4 4 4 3 4 4 28%	3831
April	1st to 10th	Day	20% 13% 4 8% 6% 5% 5% 3 4 6% 27%	2280
	11th to 20th	Day	17% 12% 3 7% 5% 4 5% 4 6% 6% 31%	2422
	21st to end	Day	23% 13% 4 7% 4 3 4 3 4 6% 30%	2470
May	1st to 10th	Day	22% 14% 5% 9% 5% 4 4 3 4 6% 23%	4387
	11th to 20th	Day	15% 10% 3 7% 5% 4 4 3 5% 7% 36%	4398
	21st to end	Day	21% 12% 3 8% 5% 5% 5% 3 5% 6% 26%	5046
June	1st to 10th	Day	23% 12% 3 7% 5% 4 4 4 4 6% 29%	2850
	11th to 20th	Day	19% 8% 3 6% 4 4 4 4 5% 8% 34%	2850
	21st to end	Day	25% 12% 3 7% 5% 4 5% 4 5% 6% 24%	2850
July	1st to 10th	Day	15% 6% 2 7% 5% 6% 6% 4 6% 8% 35%	4760
	11th to 20th	Day	12% 7% 3 8% 5% 5% 6% 5% 7% 8% 34%	4760
	21st to end	Day	13% 6% 2 5% 5% 5% 5% 5% 6% 9% 40%	4955
August	1st to 10th	Day	17% 6% 3 8% 6% 6% 6% 5% 7% 7% 30%	4215
	11th to 20th	Day	17% 6% 2 6% 5% 5% 5% 5% 6% 9% 34%	4045
	21st to end	Day	14% 6% 2 5% 4 3 4 3 5% 7% 47%	4473
September	1st to 10th	Day	19% 6% 3 6% 4 5% 4 3 5% 7% 38%	2280
	11th to 20th	Day	18% 7% 3 6% 4 4 3 2 5% 5% 43%	2207
	21st to end	Day	20% 8% 2 7% 4 4 4 3 4 6% 38%	2033
October	1st to 10th	Day	17% 6% 2 8% 5% 6% 4 4 5% 5% 38%	1900
	11th to 20th	Day	21% 11% 3 6% 4 4 4 3 5% 6% 32%	1900
	21st to end	Day	22% 12% 3 7% 4 5% 4 3 5% 6% 29%	1946
November	1st to 10th	Day	18% 11% 3 8% 5% 6% 5% 4 5% 6% 30%	1565
	11th to 20th	Day	22% 10% 5% 9% 5% 5% 5% 5% 4 6% 25%	1600
	21st to end	Day	20% 15% 5% 9% 4 4 5% 3 5% 6% 24%	1600
December	1st to 10th	Day	19% 13% 4 10% 4 5% 5% 4 6% 5% 25%	1463
	11th to 20th	Day	16% 13% 4 12% 8% 6% 4 3 5% 6% 22%	1668
	21st to end	Day	15% 13% 4 11% 5% 5% 4 3 4 6% 28%	2431
January	1st to 10th	Night	9% 12% 5% 13% 6% 6% 6% 5% 7% 7% 24%	4748
	11th to 20th	Night	15% 11% 3 8% 5% 5% 5% 4 6% 6% 31%	4760
	21st to end	Night	7% 10% 4 8% 5% 7% 4 4 5% 8% 40%	4806
February	1st to 10th	Night	9% 14% 4 8% 6% 5% 4 3 5% 6% 35%	2470
	11th to 20th	Night	12% 15% 5% 10% 5% 4 5% 3 5% 5% 30%	2403
	21st to end	Night	11% 14% 4 8% 5% 5% 4 4 5% 6% 33%	2041
March	1st to 10th	Night	11% 11% 4 10% 7% 6% 5% 4 5% 6% 31%	3515
	11th to 20th	Night	18% 21% 5% 10% 5% 5% 4 3 4 4 20%	3479
	21st to end	Night	25% 13% 3 8% 5% 3 3 3 4 6% 28%	3800
April	1st to 10th	Night	22% 12% 4 9% 5% 5% 4 3 4 5% 28%	1900
	11th to 20th	Night	19% 10% 3 8% 5% 4 3 4 4 6% 34%	1706
	21st to end	Night	23% 12% 3 6% 3 4 4 3 4 4 34%	1710
May	1st to 10th	Night	22% 12% 4 7% 5% 5% 5% 3 4 5% 27%	2561
	11th to 20th	Night	14% 8% 3 6% 3 4 5% 3 5% 8% 41%	2506
	21st to end	Night	15% 12% 4 10% 5% 4 5% 4 6% 6% 27%	2568
June	1st to 10th	Night	25% 8% 2 6% 4 4 5% 3 6% 6% 30%	1330
	11th to 20th	Night	18% 9% 2 7% 4 5% 4 4 4 6% 38%	1330
	21st to end	Night	23% 8% 3 6% 5% 5% 5% 5% 7% 5% 30%	1330
July	1st to 10th	Night	15% 6% 2 6% 3 5% 5% 3 5% 7% 43%	2210
	11th to 20th	Night	14% 7% 2 7% 5% 4 5% 4 6% 8% 40%	2210
	21st to end	Night	12% 5% 2 6% 4 3 4 4 6% 7% 48%	2578
August	1st to 10th	Night	15% 7% 2 8% 6% 5% 5% 4 5% 6% 35%	2714
	11th to 20th	Night	15% 6% 3 6% 4 4 5% 4 6% 7% 41%	2782
	21st to end	Night	14% 5% 2 5% 3 3 4 3 5% 7% 48%	3183
September	1st to 10th	Night	19% 6% 2 5% 3 4 4 3 5% 5% 43%	1900
	11th to 20th	Night	18% 6% 2 5% 3 3 3 3 5% 6% 47%	1971
	21st to end	Night	18% 7% 2 5% 3 4 3 3 4 6% 44%	2147
October	1st to 10th	Night	18% 8% 2 6% 3 4 5% 3 5% 5% 40%	2280
	11th to 20th	Night	22% 9% 3 6% 4 4 4 3 4 6% 36%	2280
	21st to end	Night	22% 10% 2 7% 4 4 4 4 4 6% 34%	2651
November	1st to 10th	Night	21% 11% 3 7% 4 4 5% 3 4 5% 34%	2733
	11th to 20th	Night	21% 12% 3 8% 4 3 4 3 6% 6% 28%	2800
	21st to end	Night	21% 14% 5% 10% 5% 4 4 3 5% 5% 25%	2800
December	1st to 10th	Night	19% 14% 3 8% 6% 5% 4 3 5% 5% 27%	2746
	11th to 20th	Night	21% 14% 4 8% 6% 5% 5% 3 4 5% 23%	3531
	21st to end	Night	18% 11% 4 13% 7% 5% 4 3 5% 5% 25%	5236

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	29% 46% 14% 8% 2	2208
	11th to 20th	Day	25% 46% 12% 13% 4	2210
	21st to end	Day	26% 48% 12% 9% 5% 1	2848
February	1st to 10th	Day	17% 66% 4 8% 4 1	1710
	11th to 20th	Day	18% 66% 4 6% 5%	1671
	21st to end	Day	16% 65% 2 11% 5% 2	1413
March	1st to 10th	Day	30% 46% 10% 11% 3 1	3328
	11th to 20th	Day	44% 44% 4 4 2 1	3480
	21st to end	Day	36% 42% 6% 11% 4 1	3831
April	1st to 10th	Day	19% 65% 4 7% 5% 1	2280
	11th to 20th	Day	17% 67% 4 7% 4 1	2422
	21st to end	Day	21% 66% 5% 4 3	2470
May	1st to 10th	Day	32% 47% 7% 12% 2	4402
	11th to 20th	Day	24% 44% 12% 17% 3	4402
	21st to end	Day	33% 45% 8% 12% 3	5046
June	1st to 10th	Day	18% 67% 5% 7% 3	2850
	11th to 20th	Day	17% 66% 5% 8% 3 1	2850
	21st to end	Day	19% 65% 6% 7% 3	2850
July	1st to 10th	Day	27% 38% 11% 15% 9%	4685
	11th to 20th	Day	27% 40% 14% 17% 3	4679
	21st to end	Day	20% 39% 17% 16% 7%	4797
August	1st to 10th	Day	31% 41% 14% 12% 2	4201
	11th to 20th	Day	28% 40% 12% 14% 5% 1	4084
	21st to end	Day	19% 39% 12% 20% 10% 1	4473
September	1st to 10th	Day	16% 62% 7% 10% 4	2280
	11th to 20th	Day	21% 60% 7% 9% 3	2207
	21st to end	Day	17% 60% 5% 11% 5% 1	2033
October	1st to 10th	Day	30% 38% 9% 17% 4 1	3160
	11th to 20th	Day	30% 40% 9% 17% 3	3140
	21st to end	Day	28% 38% 13% 13% 7%	3178
November	1st to 10th	Day	26% 57% 6% 8% 2 1	1565
	11th to 20th	Day	26% 59% 5% 6% 4 1	1600
	21st to end	Day	28% 58% 6% 5% 3	1600
December	1st to 10th	Day	24% 61% 7% 6% 2	1463
	11th to 20th	Day	32% 51% 6% 8% 3	1668
	21st to end	Day	32% 43% 13% 8% 3 1	2431
January	1st to 10th	Night	31% 49% 11% 7% 2	4748
	11th to 20th	Night	33% 43% 9% 9% 7%	4760
	21st to end	Night	26% 48% 11% 7% 6% 1	4806
February	1st to 10th	Night	17% 65% 4 7% 5% 1	2470
	11th to 20th	Night	20% 65% 4 7% 4	2406
	21st to end	Night	17% 65% 4 8% 7% 1	2041
March	1st to 10th	Night	28% 45% 8% 13% 6% 1	3524
	11th to 20th	Night	46% 43% 3 4 3 1	3480
	21st to end	Night	37% 41% 4 10% 6% 1	3800
April	1st to 10th	Night	20% 65% 3 5% 6% 1	1900
	11th to 20th	Night	18% 67% 4 8% 4	1706
	21st to end	Night	23% 66% 2 6% 3 1	1710
May	1st to 10th	Night	36% 45% 7% 10% 3	2566
	11th to 20th	Night	22% 44% 10% 19% 5%	2507
	21st to end	Night	33% 45% 8% 10% 4	2569
June	1st to 10th	Night	18% 67% 3 8% 4	1330
	11th to 20th	Night	17% 66% 4 7% 6%	1330
	21st to end	Night	18% 65% 5% 10% 3	1330
July	1st to 10th	Night	27% 39% 11% 12% 12%	2175
	11th to 20th	Night	28% 37% 13% 19% 3	2168
	21st to end	Night	19% 39% 17% 17% 7%	2496
August	1st to 10th	Night	35% 40% 9% 12% 3	2703
	11th to 20th	Night	26% 40% 13% 16% 5%	2809
	21st to end	Night	20% 39% 11% 20% 10%	3182
September	1st to 10th	Night	16% 61% 5% 12% 4	1900
	11th to 20th	Night	20% 61% 7% 11% 2	1971
	21st to end	Night	15% 61% 5% 12% 6% 1	2147
October	1st to 10th	Night	33% 38% 7% 18% 4	3800
	11th to 20th	Night	25% 38% 7% 22% 8%	3779
	21st to end	Night	32% 40% 9% 12% 7%	4373
November	1st to 10th	Night	25% 56% 6% 8% 4	2733
	11th to 20th	Night	26% 59% 6% 6% 3 1	2800
	21st to end	Night	29% 58% 7% 4 2	2800
December	1st to 10th	Night	25% 61% 6% 7% 2	2746
	11th to 20th	Night	33% 50% 6% 8% 3	3532
	21st to end	Night	35% 42% 12% 8% 2	5236

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	26% 18% 25% 27% 3 1	180
	11th to 20th	Day	28% 17% 26% 22% 4 3	180
	21st to end	Day	14% 11% 37% 26% 10% 1	328
February	1st to 10th	Day	19% 12% 38% 21% 9% 1	370
	11th to 20th	Day	16% 12% 39% 25% 7% 1	366
	21st to end	Day	15% 9% 35% 28% 11% 2	307
March	1st to 10th	Day	19% 10% 35% 26% 8% 2	442
	11th to 20th	Day	18% 11% 27% 29% 12% 2	460
	21st to end	Day	23% 13% 30% 25% 7% 1	506
April	1st to 10th	Day	25% 13% 31% 23% 8%	460
	11th to 20th	Day	21% 10% 34% 24% 9% 2	452
	21st to end	Day	26% 9% 23% 26% 13% 2	460
May	1st to 10th	Day	27% 7% 23% 29% 11% 3	628
	11th to 20th	Day	22% 7% 23% 29% 16% 4	674
	21st to end	Day	23% 10% 29% 28% 10% 1	735
June	1st to 10th	Day	27% 7% 24% 28% 12% 2	680
	11th to 20th	Day	21% 5% 22% 33% 15% 3	680
	21st to end	Day	25% 4 25% 32% 14% 1	680
July	1st to 10th	Day	17% 4 22% 39% 16% 2	670
	11th to 20th	Day	14% 4 21% 40% 19% 2	668
	21st to end	Day	18% 4 18% 36% 20% 4	740
August	1st to 10th	Day	14% 3 19% 34% 27% 2	557
	11th to 20th	Day	14% 3 19% 38% 22% 4	479
	21st to end	Day	14% 6% 23% 35% 18% 4	539
September	1st to 10th	Day	19% 5% 29% 31% 13% 2	490
	11th to 20th	Day	24% 5% 24% 30% 13% 3	490
	21st to end	Day	21% 8% 30% 27% 10% 3	460
October	1st to 10th	Day	17% 8% 32% 28% 12% 3	390
	11th to 20th	Day	29% 8% 29% 20% 12% 2	390
	21st to end	Day	28% 12% 28% 25% 6% 1	429
November	1st to 10th	Day	25% 14% 27% 26% 7% 2	395
	11th to 20th	Day	27% 15% 27% 22% 6% 2	400
	21st to end	Day	31% 14% 29% 23% 3	400
December	1st to 10th	Day	24% 10% 35% 25% 5% 1	308
	11th to 20th	Day	21% 22% 34% 18% 6%	180
	21st to end	Day	23% 20% 30% 22% 5% 1	198
January	1st to 10th	Night	24% 14% 33% 22% 6% 1	850
	11th to 20th	Night	24% 13% 34% 22% 6%	850
	21st to end	Night	17% 11% 35% 26% 10% 1	875
February	1st to 10th	Night	18% 11% 33% 27% 9% 1	760
	11th to 20th	Night	22% 10% 34% 26% 6% 1	743
	21st to end	Night	18% 11% 30% 28% 10% 3	628
March	1st to 10th	Night	19% 10% 34% 26% 9% 1	760
	11th to 20th	Night	22% 10% 31% 27% 9% 2	760
	21st to end	Night	23% 12% 28% 27% 9% 1	832
April	1st to 10th	Night	29% 8% 27% 26% 8% 1	570
	11th to 20th	Night	25% 7% 28% 27% 12% 1	564
	21st to end	Night	27% 7% 23% 29% 11% 3	570
May	1st to 10th	Night	25% 7% 19% 30% 17% 2	570
	11th to 20th	Night	22% 6% 19% 30% 19% 3	562
	21st to end	Night	22% 6% 25% 35% 11% 1	513
June	1st to 10th	Night	29% 4 20% 31% 16% 1	380
	11th to 20th	Night	23% 2 18% 36% 18% 3	380
	21st to end	Night	24% 5% 15% 34% 19% 3	380
July	1st to 10th	Night	19% 4 13% 38% 24% 2	370
	11th to 20th	Night	15% 4 17% 38% 25% 2	368
	21st to end	Night	18% 4 15% 38% 24% 1	516
August	1st to 10th	Night	18% 2 12% 39% 26% 3	568
	11th to 20th	Night	18% 2 13% 36% 28% 3	562
	21st to end	Night	16% 5% 18% 32% 25% 4	627
September	1st to 10th	Night	21% 6% 24% 32% 14% 2	570
	11th to 20th	Night	20% 8% 20% 34% 16% 2	641
	21st to end	Night	22% 8% 26% 30% 13% 1	760
October	1st to 10th	Night	23% 7% 28% 28% 12% 1	760
	11th to 20th	Night	26% 10% 27% 24% 12% 1	760
	21st to end	Night	26% 11% 29% 25% 9%	869
November	1st to 10th	Night	27% 13% 30% 23% 7% 1	880
	11th to 20th	Night	28% 15% 30% 19% 6% 2	900
	21st to end	Night	30% 15% 29% 21% 4 1	900
December	1st to 10th	Night	27% 15% 34% 18% 5%	859
	11th to 20th	Night	25% 21% 34% 15% 4 1	850
	21st to end	Night	28% 15% 31% 20% 5% 1	935

Page generated at 2024-11-29 10:43:07. Version ac07

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