Munro Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Munro Park clear sky chart from 2005-11-06 to 2026-08-15.

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% 12% 4 9% 5% 4 4 3 5% 6% 31%	144593
	Night	15% 14% 5% 11% 6% 5% 4 3 4 5% 28%	137360
Transparency	Day	54% 4 10% 21% 9% 1	148152
	Night	58% 4 9% 18% 9% 1	141890
Seeing	Day	24% 16% 31% 19% 7% 2	17331
	Night	24% 14% 30% 24% 8% 1	26221

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	10% 18% 10% 15% 8% 7% 5% 3 4 4 16%	4094
	11th to 20th	Day	9% 18% 8% 21% 8% 7% 5% 4 5% 5% 12%	4532
	21st to end	Day	9% 16% 8% 17% 8% 6% 5% 4 4 4 19%	5780
February	1st to 10th	Day	11% 20% 7% 14% 8% 5% 5% 3 4 4 18%	1890
	11th to 20th	Day	10% 18% 7% 14% 8% 5% 4 3 4 5% 22%	1843
	21st to end	Day	14% 19% 6% 13% 8% 6% 3 3 3 4 21%	1557
March	1st to 10th	Day	18% 14% 5% 11% 5% 5% 4 3 4 5% 25%	5035
	11th to 20th	Day	12% 15% 6% 12% 6% 5% 4 4 5% 7% 24%	5090
	21st to end	Day	16% 16% 7% 9% 5% 5% 3 2 4 4 29%	5586
April	1st to 10th	Day	22% 15% 4 8% 4 3 4 2 5% 6% 27%	2501
	11th to 20th	Day	22% 12% 4 6% 4 3 4 3 4 6% 32%	2628
	21st to end	Day	22% 12% 3 8% 4 3 3 3 3 5% 33%	2730
May	1st to 10th	Day	16% 12% 3 8% 5% 5% 5% 3 5% 7% 30%	7880
	11th to 20th	Day	16% 10% 3 7% 4 4 4 4 5% 7% 36%	8221
	21st to end	Day	20% 10% 2 6% 4 3 3 3 4 6% 39%	9060
June	1st to 10th	Day	20% 8% 3 7% 6% 4 4 4 5% 6% 33%	3043
	11th to 20th	Day	17% 6% 2 7% 5% 5% 5% 4 6% 7% 37%	3150
	21st to end	Day	21% 7% 3 6% 5% 4 5% 4 6% 7% 33%	3150
July	1st to 10th	Day	16% 6% 2 6% 4 5% 5% 4 7% 9% 37%	8879
	11th to 20th	Day	13% 5% 2 5% 4 3 4 4 5% 9% 47%	8700
	21st to end	Day	13% 6% 2 5% 4 4 4 3 6% 8% 45%	8821
August	1st to 10th	Day	13% 7% 2 7% 5% 5% 6% 5% 7% 8% 35%	4364
	11th to 20th	Day	19% 7% 3 6% 4 4 5% 4 6% 8% 36%	4226
	21st to end	Day	11% 5% 2 6% 5% 5% 4 4 6% 9% 44%	4551
September	1st to 10th	Day	17% 8% 3 6% 4 4 4 3 5% 7% 40%	2400
	11th to 20th	Day	17% 7% 2 5% 4 3 4 3 5% 7% 43%	2302
	21st to end	Day	22% 9% 3 7% 4 3 5% 3 4 5% 34%	2150
October	1st to 10th	Day	18% 11% 3 7% 5% 4 4 3 5% 6% 35%	2000
	11th to 20th	Day	23% 17% 3 8% 5% 4 4 3 5% 6% 23%	2000
	21st to end	Day	29% 19% 5% 7% 5% 4 3 2 4 4 20%	2181
November	1st to 10th	Day	20% 17% 4 10% 5% 3 3 3 4 6% 24%	1652
	11th to 20th	Day	16% 21% 8% 12% 6% 4 4 3 4 5% 19%	1680
	21st to end	Day	21% 23% 8% 12% 5% 5% 3 3 3 3 13%	1680
December	1st to 10th	Day	14% 22% 11% 21% 6% 5% 4 3 3 3 8%	2680
	11th to 20th	Day	14% 19% 6% 15% 8% 6% 3 3 3 4 20%	3004
	21st to end	Day	19% 19% 8% 17% 6% 3 3 3 4 4 13%	3553
January	1st to 10th	Night	11% 16% 10% 17% 11% 6% 5% 3 3 4 14%	8831
	11th to 20th	Night	9% 18% 8% 21% 8% 6% 5% 3 3 4 16%	8355
	21st to end	Night	8% 18% 9% 16% 7% 8% 6% 4 4 4 17%	8401
February	1st to 10th	Night	10% 17% 6% 14% 8% 6% 5% 3 5% 5% 22%	2730
	11th to 20th	Night	12% 16% 7% 12% 8% 5% 4 4 4 5% 22%	2663
	21st to end	Night	12% 19% 6% 12% 7% 6% 5% 3 4 4 20%	2247
March	1st to 10th	Night	14% 16% 5% 10% 4 4 4 3 5% 6% 28%	5024
	11th to 20th	Night	11% 17% 5% 11% 5% 5% 5% 4 6% 6% 26%	5089
	21st to end	Night	16% 14% 6% 10% 6% 4 3 3 4 4 29%	5588
April	1st to 10th	Night	20% 16% 5% 8% 4 3 3 3 4 5% 28%	2118
	11th to 20th	Night	19% 11% 4 6% 4 3 4 3 5% 5% 35%	1960
	21st to end	Night	19% 12% 3 8% 6% 4 3 3 5% 4 31%	1890
May	1st to 10th	Night	15% 10% 2 6% 4 5% 5% 4 6% 8% 34%	5005
	11th to 20th	Night	16% 7% 2 6% 4 3 4 4 5% 7% 41%	4639
	21st to end	Night	18% 8% 2 6% 4 4 3 3 5% 7% 41%	5114
June	1st to 10th	Night	13% 9% 3 8% 6% 5% 5% 5% 5% 6% 35%	1572
	11th to 20th	Night	16% 5% 2 6% 4 4 4 3 5% 9% 42%	1470
	21st to end	Night	15% 8% 3 7% 5% 4 4 5% 6% 8% 36%	1470
July	1st to 10th	Night	15% 5% 3 6% 4 5% 4 4 6% 7% 42%	4110
	11th to 20th	Night	15% 6% 2 6% 3 3 4 3 5% 6% 47%	4280
	21st to end	Night	15% 6% 2 5% 4 3 4 3 5% 8% 46%	5253
August	1st to 10th	Night	12% 6% 2 6% 4 4 5% 4 6% 7% 43%	3005
	11th to 20th	Night	16% 7% 2 7% 4 4 5% 3 5% 6% 41%	2911
	21st to end	Night	16% 5% 2 5% 3 4 3 3 5% 7% 48%	3313
September	1st to 10th	Night	15% 6% 2 4 4 4 3 3 4 7% 48%	2000
	11th to 20th	Night	16% 7% 1 6% 4 3 2 2 4 6% 48%	2095
	21st to end	Night	17% 9% 2 6% 3 4 3 3 5% 6% 41%	2250
October	1st to 10th	Night	19% 10% 3 7% 4 4 4 3 4 6% 37%	2400
	11th to 20th	Night	24% 15% 3 8% 4 4 4 3 5% 5% 26%	2400
	21st to end	Night	25% 19% 3 8% 4 4 3 3 4 4 23%	2655
November	1st to 10th	Night	19% 16% 4 7% 5% 4 4 3 4 5% 28%	2864
	11th to 20th	Night	17% 18% 5% 11% 6% 5% 4 3 4 5% 22%	2940
	21st to end	Night	21% 21% 6% 12% 6% 4 3 3 4 4 16%	2940
December	1st to 10th	Night	14% 24% 8% 19% 9% 5% 4 3 3 3 8%	4720
	11th to 20th	Night	14% 19% 6% 16% 8% 5% 4 3 4 4 18%	5391
	21st to end	Night	18% 20% 7% 16% 6% 4 5% 2 3 3 15%	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	72% 3 7% 13% 4 1	4095
	11th to 20th	Day	75% 4 5% 9% 7%	4562
	21st to end	Day	70% 3 5% 12% 9% 1	5780
February	1st to 10th	Day	70% 4 6% 12% 7% 1	1890
	11th to 20th	Day	65% 4 10% 12% 8% 1	1852
	21st to end	Day	68% 4 5% 15% 8%	1557
March	1st to 10th	Day	62% 4 9% 8% 14% 2	5038
	11th to 20th	Day	60% 4 12% 15% 8% 1	5090
	21st to end	Day	59% 5% 7% 18% 10% 2	5586
April	1st to 10th	Day	59% 4 8% 18% 9% 2	2501
	11th to 20th	Day	54% 4 7% 21% 12% 1	2628
	21st to end	Day	55% 4 7% 18% 14% 3	2730
May	1st to 10th	Day	53% 5% 8% 21% 9% 4	7889
	11th to 20th	Day	48% 5% 9% 25% 13% 1	8225
	21st to end	Day	48% 4 11% 22% 14% 2	9061
June	1st to 10th	Day	51% 6% 9% 21% 13%	3043
	11th to 20th	Day	46% 5% 10% 25% 13% 1	3150
	21st to end	Day	49% 6% 11% 21% 11% 1	3150
July	1st to 10th	Day	43% 5% 15% 25% 11%	8806
	11th to 20th	Day	35% 4 14% 37% 9%	8619
	21st to end	Day	39% 4 14% 31% 12%	8625
August	1st to 10th	Day	45% 6% 12% 29% 8%	4351
	11th to 20th	Day	46% 6% 14% 26% 8%	4265
	21st to end	Day	38% 5% 12% 34% 11%	4551
September	1st to 10th	Day	45% 6% 13% 25% 11%	2400
	11th to 20th	Day	41% 5% 12% 30% 11%	2302
	21st to end	Day	54% 5% 9% 24% 8%	2150
October	1st to 10th	Day	50% 4 12% 26% 7% 1	3260
	11th to 20th	Day	55% 5% 13% 19% 7%	3240
	21st to end	Day	69% 4 11% 11% 4	3507
November	1st to 10th	Day	61% 6% 12% 16% 5%	1652
	11th to 20th	Day	68% 5% 10% 11% 6% 1	1680
	21st to end	Day	77% 5% 8% 8% 2	1680
December	1st to 10th	Day	83% 3 7% 6% 1	2680
	11th to 20th	Day	71% 4 5% 14% 6%	3004
	21st to end	Day	76% 4 4 14% 3	3553
January	1st to 10th	Night	76% 4 6% 10% 4	8831
	11th to 20th	Night	73% 4 6% 8% 8%	8400
	21st to end	Night	71% 3 5% 11% 9% 1	8401
February	1st to 10th	Night	65% 4 8% 14% 8% 1	2730
	11th to 20th	Night	64% 4 10% 16% 5% 1	2665
	21st to end	Night	67% 5% 7% 14% 6% 1	2247
March	1st to 10th	Night	57% 5% 9% 13% 13% 4	5034
	11th to 20th	Night	59% 5% 13% 15% 8% 1	5090
	21st to end	Night	59% 4 5% 18% 12% 2	5588
April	1st to 10th	Night	59% 4 7% 18% 11% 2	2118
	11th to 20th	Night	51% 3 8% 22% 14% 1	1960
	21st to end	Night	56% 4 7% 17% 14% 3	1890
May	1st to 10th	Night	47% 5% 7% 26% 12% 3	5012
	11th to 20th	Night	42% 6% 10% 24% 15% 2	4640
	21st to end	Night	43% 4 9% 28% 14% 1	5115
June	1st to 10th	Night	49% 6% 9% 21% 13% 3	1572
	11th to 20th	Night	40% 5% 11% 27% 16% 1	1470
	21st to end	Night	45% 6% 13% 23% 11% 1	1470
July	1st to 10th	Night	42% 4 14% 28% 12% 1	4075
	11th to 20th	Night	38% 3 14% 33% 10%	4238
	21st to end	Night	38% 4 12% 33% 12%	5134
August	1st to 10th	Night	40% 5% 15% 26% 12% 2	2994
	11th to 20th	Night	42% 6% 17% 25% 8% 1	2938
	21st to end	Night	37% 5% 14% 32% 11% 1	3313
September	1st to 10th	Night	37% 5% 16% 29% 12% 1	2000
	11th to 20th	Night	39% 4 15% 29% 12%	2095
	21st to end	Night	45% 5% 14% 26% 11%	2250
October	1st to 10th	Night	45% 5% 9% 28% 12%	3920
	11th to 20th	Night	55% 3 13% 21% 8%	3899
	21st to end	Night	62% 4 17% 12% 5%	4279
November	1st to 10th	Night	59% 5% 13% 18% 5%	2864
	11th to 20th	Night	65% 4 12% 12% 5% 1	2940
	21st to end	Night	73% 6% 10% 8% 3	2940
December	1st to 10th	Night	83% 4 6% 6% 2	4720
	11th to 20th	Night	71% 4 6% 11% 9%	5391
	21st to end	Night	76% 3 5% 11% 4	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	22% 29% 27% 15% 7% 1	220
	11th to 20th	Day	23% 19% 36% 14% 8%	237
	21st to end	Day	26% 16% 35% 18% 5% 1	363
February	1st to 10th	Day	30% 24% 34% 9% 1 2	330
	11th to 20th	Day	22% 29% 36% 11% 1	330
	21st to end	Day	33% 22% 35% 8% 1	273
March	1st to 10th	Day	27% 22% 35% 13% 2	533
	11th to 20th	Day	23% 23% 36% 13% 4 1	540
	21st to end	Day	30% 23% 27% 16% 4 1	594
April	1st to 10th	Day	31% 19% 29% 15% 4 1	540
	11th to 20th	Day	37% 16% 22% 13% 9% 2	532
	21st to end	Day	30% 20% 28% 15% 4 1	540
May	1st to 10th	Day	28% 17% 30% 16% 7% 2	543
	11th to 20th	Day	24% 17% 29% 19% 10% 2	567
	21st to end	Day	24% 16% 31% 19% 9% 2	617
June	1st to 10th	Day	22% 14% 34% 23% 7% 1	673
	11th to 20th	Day	20% 15% 34% 21% 7% 2	780
	21st to end	Day	23% 14% 35% 18% 9% 1	780
July	1st to 10th	Day	14% 11% 33% 31% 9% 1	771
	11th to 20th	Day	17% 13% 30% 27% 11% 2	705
	21st to end	Day	15% 11% 31% 28% 12% 2	620
August	1st to 10th	Day	19% 8% 28% 28% 12% 4	566
	11th to 20th	Day	19% 5% 27% 27% 14% 7%	535
	21st to end	Day	17% 13% 30% 25% 11% 4	583
September	1st to 10th	Day	20% 13% 28% 23% 10% 5%	530
	11th to 20th	Day	18% 7% 26% 26% 14% 8%	530
	21st to end	Day	24% 13% 24% 23% 13% 2	530
October	1st to 10th	Day	24% 14% 28% 22% 11% 2	530
	11th to 20th	Day	28% 19% 35% 13% 4 1	530
	21st to end	Day	38% 16% 29% 14% 2 1	564
November	1st to 10th	Day	31% 21% 34% 11% 3	223
	11th to 20th	Day	27% 23% 40% 7% 3 1	220
	21st to end	Day	33% 20% 38% 8% 1	220
December	1st to 10th	Day	28% 20% 32% 17% 2	220
	11th to 20th	Day	30% 23% 30% 14% 3	220
	21st to end	Day	33% 20% 26% 16% 4	242
January	1st to 10th	Night	25% 16% 34% 19% 5% 1	1050
	11th to 20th	Night	27% 17% 30% 21% 4	919
	21st to end	Night	20% 12% 34% 24% 8% 1	924
February	1st to 10th	Night	19% 21% 36% 19% 4	840
	11th to 20th	Night	21% 19% 35% 20% 5%	823
	21st to end	Night	23% 19% 36% 19% 2	692
March	1st to 10th	Night	21% 22% 34% 20% 3	840
	11th to 20th	Night	25% 20% 32% 18% 5% 1	840
	21st to end	Night	22% 15% 32% 23% 6% 1	924
April	1st to 10th	Night	31% 14% 32% 19% 4	840
	11th to 20th	Night	26% 18% 25% 22% 8% 1	716
	21st to end	Night	25% 15% 28% 24% 9% 1	630
May	1st to 10th	Night	21% 10% 30% 29% 9% 1	545
	11th to 20th	Night	21% 10% 32% 28% 9% 1	414
	21st to end	Night	19% 10% 34% 30% 7%	455
June	1st to 10th	Night	16% 10% 33% 31% 10%	420
	11th to 20th	Night	18% 11% 25% 35% 11%	420
	21st to end	Night	17% 5% 32% 31% 13% 1	420
July	1st to 10th	Night	14% 4 28% 41% 11%	410
	11th to 20th	Night	14% 5% 29% 34% 18%	408
	21st to end	Night	13% 5% 28% 38% 16%	515
August	1st to 10th	Night	16% 4 23% 38% 17% 1	627
	11th to 20th	Night	17% 5% 19% 37% 20% 2	606
	21st to end	Night	20% 8% 25% 28% 16% 2	711
September	1st to 10th	Night	19% 6% 28% 29% 17% 1	800
	11th to 20th	Night	19% 7% 26% 26% 20% 3	800
	21st to end	Night	21% 9% 23% 29% 16% 2	800
October	1st to 10th	Night	23% 11% 30% 25% 9% 1	800
	11th to 20th	Night	32% 14% 27% 19% 7% 1	800
	21st to end	Night	36% 14% 27% 19% 3	880
November	1st to 10th	Night	31% 14% 30% 18% 7% 1	820
	11th to 20th	Night	26% 19% 31% 17% 6%	840
	21st to end	Night	33% 17% 29% 19% 3	840
December	1st to 10th	Night	29% 19% 31% 16% 5%	840
	11th to 20th	Night	26% 18% 34% 17% 3 2	857
	21st to end	Night	31% 17% 30% 18% 4	1155

Page generated at 2026-08-12 03:37:19. Version ac07

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