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 2025-04-11.

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% 12% 4 9% 5% 4 4 3 5% 6% 29%	113524
	Night	15% 14% 5% 11% 6% 5% 4 3 4 5% 27%	114775
Transparency	Day	56% 5% 10% 20% 9% 1	117129
	Night	59% 5% 10% 17% 9% 1	119334
Seeing	Day	24% 16% 30% 19% 8% 2	15483
	Night	24% 14% 30% 23% 8% 1	24658

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% 19% 10% 16% 9% 7% 5% 2 3 3 14%	3158
	11th to 20th	Day	9% 17% 7% 19% 8% 7% 5% 4 5% 5% 14%	3476
	21st to end	Day	11% 20% 9% 16% 7% 5% 4 3 4 4 17%	4466
February	1st to 10th	Day	11% 20% 7% 15% 8% 5% 5% 3 4 4 18%	1800
	11th to 20th	Day	10% 18% 7% 13% 8% 5% 4 3 4 5% 23%	1753
	21st to end	Day	15% 19% 5% 13% 8% 6% 3 3 3 4 21%	1485
March	1st to 10th	Day	18% 14% 5% 11% 5% 5% 4 3 4 5% 25%	4925
	11th to 20th	Day	11% 15% 6% 12% 6% 5% 4 4 5% 7% 25%	4980
	21st to end	Day	16% 16% 7% 9% 5% 5% 3 2 4 4 30%	5465
April	1st to 10th	Day	22% 15% 5% 7% 4 3 4 2 5% 6% 27%	2382
	11th to 20th	Day	21% 12% 4 6% 4 3 4 3 4 6% 32%	2375
	21st to end	Day	22% 12% 3 8% 4 3 3 3 3 5% 33%	2470
May	1st to 10th	Day	21% 10% 3 7% 4 4 4 3 5% 7% 32%	4236
	11th to 20th	Day	16% 9% 2 7% 5% 4 4 4 6% 8% 37%	4398
	21st to end	Day	20% 7% 2 6% 4 4 3 3 4 7% 41%	4837
June	1st to 10th	Day	20% 8% 3 8% 6% 4 4 4 5% 7% 32%	2753
	11th to 20th	Day	16% 6% 2 6% 6% 5% 5% 4 6% 7% 38%	2850
	21st to end	Day	21% 7% 3 6% 6% 4 5% 4 6% 7% 32%	2850
July	1st to 10th	Day	17% 7% 2 7% 5% 5% 5% 4 6% 7% 35%	4760
	11th to 20th	Day	16% 7% 2 6% 4 4 4 4 6% 8% 38%	4664
	21st to end	Day	13% 6% 2 5% 4 4 4 3 5% 7% 47%	4726
August	1st to 10th	Day	13% 7% 3 7% 5% 5% 6% 5% 7% 8% 35%	4104
	11th to 20th	Day	20% 7% 3 6% 4 4 5% 4 5% 8% 36%	4044
	21st to end	Day	11% 5% 2 6% 5% 5% 4 4 6% 9% 44%	4412
September	1st to 10th	Day	17% 8% 3 5% 4 4 4 3 5% 7% 40%	2280
	11th to 20th	Day	17% 7% 2 5% 4 3 4 3 5% 7% 43%	2187
	21st to end	Day	22% 9% 3 7% 4 3 5% 3 4 4 34%	2043
October	1st to 10th	Day	19% 12% 3 7% 5% 4 4 3 5% 6% 34%	1900
	11th to 20th	Day	23% 17% 3 8% 5% 4 4 3 5% 6% 22%	1900
	21st to end	Day	30% 19% 5% 7% 5% 4 3 2 4 4 19%	2072
November	1st to 10th	Day	19% 17% 4 10% 5% 3 3 3 5% 6% 24%	1572
	11th to 20th	Day	16% 20% 7% 12% 6% 4 4 3 4 5% 19%	1600
	21st to end	Day	22% 23% 8% 11% 6% 6% 3 3 4 3 13%	1600
December	1st to 10th	Day	15% 22% 11% 21% 6% 5% 4 3 3 4 8%	2600
	11th to 20th	Day	14% 19% 6% 14% 7% 6% 4 3 3 4 20%	2925
	21st to end	Day	19% 19% 9% 17% 6% 3 3 3 4 4 13%	3476
January	1st to 10th	Night	12% 17% 9% 16% 11% 6% 4 3 3 4 16%	6808
	11th to 20th	Night	8% 16% 7% 20% 9% 6% 5% 3 4 4 16%	6407
	21st to end	Night	10% 22% 10% 15% 5% 6% 5% 3 4 4 16%	6490
February	1st to 10th	Night	11% 17% 6% 14% 8% 6% 5% 3 4 5% 21%	2600
	11th to 20th	Night	12% 15% 7% 12% 8% 5% 4 4 4 5% 23%	2533
	21st to end	Night	12% 19% 6% 12% 7% 6% 5% 3 4 4 21%	2143
March	1st to 10th	Night	14% 16% 5% 10% 4 4 4 3 5% 6% 28%	4914
	11th to 20th	Night	11% 17% 5% 11% 5% 5% 5% 4 6% 6% 26%	4979
	21st to end	Night	16% 14% 6% 10% 6% 4 3 3 4 4 29%	5467
April	1st to 10th	Night	20% 16% 4 7% 5% 3 3 4 5% 5% 29%	2017
	11th to 20th	Night	20% 11% 4 6% 4 3 4 2 5% 5% 36%	1779
	21st to end	Night	20% 12% 4 7% 6% 4 3 3 5% 4 31%	1710
May	1st to 10th	Night	16% 10% 2 6% 4 4 4 4 6% 7% 38%	2691
	11th to 20th	Night	14% 7% 2 6% 5% 4 5% 4 6% 8% 40%	2495
	21st to end	Night	14% 8% 2 7% 5% 4 4 3 5% 8% 40%	2738
June	1st to 10th	Night	14% 10% 3 8% 5% 5% 5% 5% 5% 6% 35%	1422
	11th to 20th	Night	16% 5% 2 6% 4 4 4 3 5% 9% 43%	1330
	21st to end	Night	15% 8% 3 8% 4 4 4 4 6% 7% 37%	1330
July	1st to 10th	Night	16% 6% 2 7% 4 4 3 3 5% 7% 44%	2210
	11th to 20th	Night	18% 6% 2 7% 3 4 3 3 5% 5% 43%	2302
	21st to end	Night	13% 6% 2 4 4 4 4 3 5% 8% 48%	2824
August	1st to 10th	Night	12% 6% 3 6% 4 4 5% 4 6% 7% 43%	2825
	11th to 20th	Night	16% 7% 2 7% 4 4 5% 3 5% 6% 41%	2785
	21st to end	Night	16% 5% 2 5% 3 4 3 3 5% 7% 48%	3211
September	1st to 10th	Night	15% 5% 2 4 4 4 3 3 4 7% 49%	1900
	11th to 20th	Night	17% 7% 1 6% 4 4 3 2 4 6% 47%	1990
	21st to end	Night	17% 8% 2 7% 3 4 3 3 5% 7% 40%	2137
October	1st to 10th	Night	19% 10% 3 7% 4 4 4 3 4 6% 35%	2280
	11th to 20th	Night	23% 15% 3 8% 5% 4 4 3 5% 5% 25%	2280
	21st to end	Night	26% 19% 3 8% 4 4 3 3 4 4 22%	2522
November	1st to 10th	Night	19% 16% 4 7% 5% 4 4 3 4 5% 29%	2724
	11th to 20th	Night	18% 17% 5% 11% 6% 5% 4 3 4 5% 22%	2800
	21st to end	Night	21% 20% 6% 12% 6% 4 3 3 4 4 17%	2800
December	1st to 10th	Night	14% 25% 8% 19% 9% 5% 4 3 3 3 8%	4580
	11th to 20th	Night	14% 19% 6% 15% 8% 5% 4 3 4 4 18%	5250
	21st to end	Night	18% 20% 7% 17% 6% 4 5% 2 3 3 15%	7502

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	76% 3 7% 11% 4	3159
	11th to 20th	Day	72% 4 7% 9% 7% 1	3506
	21st to end	Day	71% 4 5% 11% 8% 1	4466
February	1st to 10th	Day	71% 4 6% 12% 6% 1	1800
	11th to 20th	Day	65% 4 10% 12% 8% 1	1762
	21st to end	Day	68% 4 5% 15% 7%	1485
March	1st to 10th	Day	62% 4 9% 8% 15% 2	4928
	11th to 20th	Day	59% 4 12% 16% 8% 1	4980
	21st to end	Day	59% 5% 7% 18% 10% 2	5465
April	1st to 10th	Day	59% 4 8% 18% 10% 2	2382
	11th to 20th	Day	54% 5% 8% 21% 12% 1	2375
	21st to end	Day	55% 4 7% 17% 14% 3	2470
May	1st to 10th	Day	52% 7% 7% 22% 11% 2	4248
	11th to 20th	Day	44% 7% 10% 29% 8% 1	4402
	21st to end	Day	44% 5% 12% 19% 17% 2	4837
June	1st to 10th	Day	51% 6% 10% 20% 12%	2753
	11th to 20th	Day	45% 6% 10% 25% 13% 1	2850
	21st to end	Day	50% 7% 11% 19% 11% 1	2850
July	1st to 10th	Day	47% 6% 14% 24% 9% 1	4686
	11th to 20th	Day	42% 6% 14% 30% 7%	4583
	21st to end	Day	37% 5% 11% 31% 16%	4575
August	1st to 10th	Day	46% 6% 11% 30% 7%	4091
	11th to 20th	Day	46% 6% 14% 26% 8% 1	4083
	21st to end	Day	38% 5% 12% 34% 11%	4412
September	1st to 10th	Day	45% 6% 12% 25% 12%	2280
	11th to 20th	Day	42% 5% 13% 29% 11%	2187
	21st to end	Day	54% 6% 10% 23% 8%	2043
October	1st to 10th	Day	51% 5% 11% 26% 7% 1	3160
	11th to 20th	Day	55% 5% 14% 19% 7%	3140
	21st to end	Day	69% 4 11% 11% 4	3398
November	1st to 10th	Day	61% 6% 12% 16% 5%	1572
	11th to 20th	Day	68% 5% 10% 11% 6% 1	1600
	21st to end	Day	77% 5% 8% 8% 2	1600
December	1st to 10th	Day	83% 4 7% 5% 1	2600
	11th to 20th	Day	70% 4 5% 14% 6%	2925
	21st to end	Day	76% 4 4 13% 3	3476
January	1st to 10th	Night	74% 4 6% 11% 4	6808
	11th to 20th	Night	71% 5% 8% 8% 7%	6452
	21st to end	Night	73% 3 5% 9% 9% 1	6490
February	1st to 10th	Night	66% 4 9% 13% 8% 1	2600
	11th to 20th	Night	64% 5% 10% 16% 5% 1	2535
	21st to end	Night	66% 5% 7% 14% 7% 1	2143
March	1st to 10th	Night	57% 5% 9% 13% 13% 4	4924
	11th to 20th	Night	58% 5% 13% 15% 8% 1	4980
	21st to end	Night	59% 4 5% 18% 12% 2	5467
April	1st to 10th	Night	58% 4 6% 19% 11% 2	2017
	11th to 20th	Night	51% 3 7% 22% 14% 2	1779
	21st to end	Night	56% 4 7% 15% 15% 3	1710
May	1st to 10th	Night	46% 6% 10% 25% 12% 1	2698
	11th to 20th	Night	41% 8% 11% 26% 13% 2	2496
	21st to end	Night	43% 5% 11% 24% 16% 2	2739
June	1st to 10th	Night	49% 7% 9% 22% 10% 3	1422
	11th to 20th	Night	39% 6% 10% 27% 17% 1	1330
	21st to end	Night	46% 7% 13% 22% 11% 1	1330
July	1st to 10th	Night	41% 4 14% 27% 14% 1	2175
	11th to 20th	Night	43% 5% 14% 29% 8% 1	2260
	21st to end	Night	36% 5% 11% 31% 17% 1	2734
August	1st to 10th	Night	40% 5% 15% 26% 12% 2	2814
	11th to 20th	Night	43% 7% 16% 25% 8% 1	2812
	21st to end	Night	37% 5% 14% 31% 12% 1	3211
September	1st to 10th	Night	37% 5% 15% 30% 12% 1	1900
	11th to 20th	Night	40% 4 15% 28% 12%	1990
	21st to end	Night	45% 5% 14% 26% 10%	2137
October	1st to 10th	Night	46% 5% 9% 28% 12%	3800
	11th to 20th	Night	55% 3 13% 21% 8%	3779
	21st to end	Night	62% 4 17% 12% 5%	4146
November	1st to 10th	Night	58% 5% 13% 18% 5%	2724
	11th to 20th	Night	64% 5% 12% 13% 6% 1	2800
	21st to end	Night	73% 6% 10% 8% 3	2800
December	1st to 10th	Night	83% 4 6% 6% 2	4580
	11th to 20th	Night	71% 4 5% 11% 9%	5250
	21st to end	Night	76% 3 5% 11% 4	7502

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	23% 29% 25% 15% 8% 1	200
	11th to 20th	Day	20% 20% 35% 16% 8%	215
	21st to end	Day	26% 17% 33% 18% 5% 1	330
February	1st to 10th	Day	30% 27% 33% 8% 2	300
	11th to 20th	Day	22% 31% 36% 10% 1	300
	21st to end	Day	35% 23% 34% 8% 1	249
March	1st to 10th	Day	26% 22% 35% 14% 2	493
	11th to 20th	Day	20% 23% 38% 13% 5% 1	500
	21st to end	Day	29% 23% 27% 17% 4 1	550
April	1st to 10th	Day	30% 19% 29% 16% 5% 1	500
	11th to 20th	Day	36% 18% 22% 14% 9% 2	452
	21st to end	Day	30% 20% 28% 15% 5% 2	460
May	1st to 10th	Day	28% 15% 29% 18% 8% 2	463
	11th to 20th	Day	24% 16% 28% 20% 10% 2	487
	21st to end	Day	22% 15% 32% 19% 10% 2	529
June	1st to 10th	Day	22% 14% 33% 23% 6% 1	583
	11th to 20th	Day	18% 14% 35% 22% 8% 3	680
	21st to end	Day	23% 14% 34% 18% 10% 1	680
July	1st to 10th	Day	14% 11% 32% 32% 9% 1	671
	11th to 20th	Day	18% 13% 28% 28% 12% 2	611
	21st to end	Day	15% 11% 29% 30% 13% 3	532
August	1st to 10th	Day	20% 8% 27% 28% 13% 5%	486
	11th to 20th	Day	20% 4 24% 27% 16% 8%	479
	21st to end	Day	17% 13% 30% 25% 11% 5%	539
September	1st to 10th	Day	20% 13% 28% 23% 11% 5%	490
	11th to 20th	Day	19% 8% 27% 25% 13% 7%	490
	21st to end	Day	25% 14% 23% 22% 13% 2	490
October	1st to 10th	Day	25% 14% 28% 20% 11% 2	490
	11th to 20th	Day	28% 20% 34% 13% 4 1	490
	21st to end	Day	40% 17% 29% 13% 2 1	521
November	1st to 10th	Day	30% 21% 35% 11% 3	203
	11th to 20th	Day	28% 24% 39% 7% 3 1	200
	21st to end	Day	32% 21% 39% 8% 1 1	200
December	1st to 10th	Day	28% 21% 33% 17% 2	200
	11th to 20th	Day	30% 23% 31% 14% 3 1	200
	21st to end	Day	32% 20% 26% 17% 4	220
January	1st to 10th	Night	26% 17% 34% 19% 5% 1	1000
	11th to 20th	Night	27% 17% 30% 21% 5%	875
	21st to end	Night	21% 12% 34% 24% 9% 1	880
February	1st to 10th	Night	20% 21% 36% 18% 4	800
	11th to 20th	Night	20% 19% 35% 20% 5%	783
	21st to end	Night	23% 19% 36% 19% 2	660
March	1st to 10th	Night	21% 22% 34% 20% 4	800
	11th to 20th	Night	24% 20% 33% 18% 5% 1	800
	21st to end	Night	21% 15% 32% 24% 7% 1	880
April	1st to 10th	Night	31% 13% 32% 19% 4	800
	11th to 20th	Night	27% 18% 24% 22% 8% 1	651
	21st to end	Night	25% 14% 26% 24% 9% 1	570
May	1st to 10th	Night	22% 9% 30% 30% 9% 1	493
	11th to 20th	Night	20% 10% 31% 28% 9% 1	374
	21st to end	Night	17% 9% 34% 31% 8%	411
June	1st to 10th	Night	17% 9% 33% 31% 11%	380
	11th to 20th	Night	18% 10% 25% 36% 12%	380
	21st to end	Night	18% 6% 30% 32% 14% 1	380
July	1st to 10th	Night	15% 4 28% 40% 12% 1	370
	11th to 20th	Night	13% 5% 27% 35% 19% 1	368
	21st to end	Night	14% 5% 27% 37% 17%	465
August	1st to 10th	Night	17% 4 23% 36% 19% 1	567
	11th to 20th	Night	16% 5% 19% 37% 21% 3	564
	21st to end	Night	20% 8% 25% 28% 16% 2	675
September	1st to 10th	Night	19% 6% 27% 30% 17% 1	760
	11th to 20th	Night	20% 7% 26% 25% 19% 3	760
	21st to end	Night	22% 9% 23% 28% 16% 2	760
October	1st to 10th	Night	24% 12% 29% 24% 9% 1	760
	11th to 20th	Night	32% 14% 27% 19% 7% 1	760
	21st to end	Night	36% 15% 28% 17% 3	836
November	1st to 10th	Night	30% 13% 30% 19% 7% 1	780
	11th to 20th	Night	27% 19% 31% 17% 6%	800
	21st to end	Night	32% 16% 28% 19% 3	800
December	1st to 10th	Night	30% 19% 30% 16% 5%	800
	11th to 20th	Night	26% 18% 34% 17% 3 2	816
	21st to end	Night	30% 17% 29% 19% 4	1100

Page generated at 2025-04-08 09:17:26. Version ac07

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