Muskegon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Muskegon clear sky chart from 2005-11-06 to 2024-11-25.

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	14% 10% 4 8% 5% 4 4 3 5% 7% 36%	101504
	Night	15% 13% 5% 9% 5% 4 4 3 5% 6% 31%	98042
Transparency	Day	47% 6% 12% 22% 12% 1	105062
	Night	53% 5% 11% 19% 11% 1	102625
Seeing	Day	18% 14% 31% 23% 11% 3	15925
	Night	20% 10% 28% 28% 12% 1	25789

By Month

Percentage Cloud Cover SE (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	15% 26% 12% 14% 8% 5% 4 2 2 3 9%	2527
	11th to 20th	Day	13% 18% 8% 20% 16% 8% 3 3 3 3 6%	2530
	21st to end	Day	20% 24% 8% 18% 7% 5% 3 2 2 2 9%	2783
February	1st to 10th	Day	11% 17% 6% 14% 13% 7% 5% 2 5% 4 17%	1718
	11th to 20th	Day	12% 15% 6% 16% 8% 6% 5% 3 4 5% 20%	1848
	21st to end	Day	14% 15% 6% 13% 6% 6% 5% 4 5% 5% 22%	1570
March	1st to 10th	Day	14% 12% 5% 8% 5% 5% 5% 4 6% 6% 32%	3120
	11th to 20th	Day	11% 8% 6% 11% 5% 5% 4 4 4 5% 36%	3342
	21st to end	Day	20% 11% 6% 8% 4 4 3 4 5% 5% 29%	4027
April	1st to 10th	Day	18% 12% 4 7% 5% 4 4 3 5% 7% 31%	2280
	11th to 20th	Day	18% 9% 3 6% 4 5% 4 3 4 7% 36%	2286
	21st to end	Day	16% 9% 3 7% 5% 4 4 3 5% 8% 36%	2470
May	1st to 10th	Day	16% 7% 3 5% 4 4 4 4 5% 8% 41%	4082
	11th to 20th	Day	13% 7% 2 6% 4 4 4 4 5% 7% 45%	4191
	21st to end	Day	9% 6% 2 5% 4 4 4 4 6% 8% 47%	4824
June	1st to 10th	Day	10% 5% 2 5% 5% 3 4 4 6% 8% 47%	2660
	11th to 20th	Day	11% 5% 1 5% 4 4 3 4 6% 9% 48%	2660
	21st to end	Day	11% 5% 2 5% 4 4 4 4 6% 10% 45%	2660
July	1st to 10th	Day	13% 7% 3 7% 4 4 4 3 6% 7% 42%	4440
	11th to 20th	Day	6% 3 2 5% 3 4 4 3 6% 8% 57%	4440
	21st to end	Day	7% 5% 2 5% 4 4 5% 4 6% 8% 49%	4813
August	1st to 10th	Day	10% 5% 2 6% 4 5% 5% 4 6% 9% 44%	4231
	11th to 20th	Day	12% 4 2 5% 4 4 4 3 6% 7% 51%	4044
	21st to end	Day	9% 5% 2 6% 4 4 4 4 6% 8% 47%	4181
September	1st to 10th	Day	10% 6% 2 6% 4 4 4 3 5% 8% 46%	2275
	11th to 20th	Day	12% 5% 2 4 4 4 4 4 5% 8% 48%	2090
	21st to end	Day	12% 6% 3 7% 4 4 4 4 6% 8% 41%	2090
October	1st to 10th	Day	16% 8% 2 7% 4 4 4 3 4 6% 43%	2090
	11th to 20th	Day	23% 9% 2 9% 6% 5% 6% 4 4 7% 24%	1831
	21st to end	Day	23% 12% 4 8% 6% 4 5% 3 5% 6% 24%	1881
November	1st to 10th	Day	15% 14% 4 7% 5% 4 4 4 4 6% 33%	1762
	11th to 20th	Day	17% 22% 5% 10% 5% 5% 4 3 4 5% 20%	1800
	21st to end	Day	23% 18% 6% 10% 6% 4 3 2 4 5% 18%	1737
December	1st to 10th	Day	15% 26% 12% 14% 5% 3 2 2 3 3 13%	1520
	11th to 20th	Day	15% 24% 11% 14% 6% 5% 4 3 3 4 10%	1918
	21st to end	Day	22% 25% 8% 12% 6% 4 3 3 4 4 9%	2783
January	1st to 10th	Night	16% 26% 10% 14% 7% 4 3 2 3 3 12%	4428
	11th to 20th	Night	14% 19% 10% 20% 12% 7% 3 3 3 2 8%	4440
	21st to end	Night	20% 22% 10% 15% 7% 4 4 2 3 3 8%	4884
February	1st to 10th	Night	12% 19% 5% 15% 10% 6% 4 3 4 4 17%	2456
	11th to 20th	Night	14% 15% 7% 13% 9% 6% 4 4 4 4 21%	2218
	21st to end	Night	15% 17% 4 11% 6% 5% 3 4 4 5% 24%	1884
March	1st to 10th	Night	17% 9% 4 8% 5% 4 4 3 4 6% 36%	3733
	11th to 20th	Night	9% 8% 3 8% 6% 4 4 3 5% 7% 42%	3618
	21st to end	Night	17% 12% 4 11% 6% 5% 5% 3 5% 6% 27%	3633
April	1st to 10th	Night	16% 10% 3 7% 5% 5% 4 3 5% 7% 34%	1900
	11th to 20th	Night	20% 9% 3 6% 4 4 5% 4 5% 4 36%	1842
	21st to end	Night	16% 9% 2 7% 4 4 3 4 5% 6% 39%	1710
May	1st to 10th	Night	15% 8% 3 8% 5% 5% 4 4 5% 7% 37%	2813
	11th to 20th	Night	16% 7% 2 6% 5% 4 5% 4 6% 9% 37%	2704
	21st to end	Night	16% 9% 3 7% 5% 3 4 3 4 6% 40%	2743
June	1st to 10th	Night	11% 5% 2 5% 4 4 4 4 8% 8% 44%	1520
	11th to 20th	Night	9% 5% 2 7% 4 4 3 4 6% 9% 46%	1520
	21st to end	Night	10% 7% 2 5% 4 4 4 4 6% 9% 46%	1520
July	1st to 10th	Night	10% 8% 2 7% 4 5% 5% 4 7% 7% 40%	2530
	11th to 20th	Night	6% 4 2 4 4 5% 4 4 6% 8% 55%	2530
	21st to end	Night	7% 6% 3 6% 5% 3 3 4 6% 7% 50%	2750
August	1st to 10th	Night	9% 5% 2 5% 4 4 4 4 5% 9% 49%	2702
	11th to 20th	Night	12% 5% 1 5% 4 4 4 4 5% 6% 52%	2785
	21st to end	Night	8% 6% 2 7% 5% 4 5% 4 5% 8% 47%	3471
September	1st to 10th	Night	9% 6% 2 6% 4 4 4 4 6% 6% 50%	1900
	11th to 20th	Night	10% 4 2 4 3 3 3 3 5% 7% 55%	2074
	21st to end	Night	14% 6% 2 8% 5% 5% 4 4 6% 6% 41%	2090
October	1st to 10th	Night	18% 6% 2 6% 3 3 3 3 4 6% 46%	2090
	11th to 20th	Night	23% 11% 3 7% 4 3 3 3 4 6% 33%	2345
	21st to end	Night	25% 10% 2 8% 5% 4 4 2 5% 6% 30%	2717
November	1st to 10th	Night	16% 13% 3 7% 4 4 4 3 5% 6% 35%	2536
	11th to 20th	Night	18% 19% 6% 11% 5% 4 4 3 6% 4 20%	2600
	21st to end	Night	19% 21% 5% 10% 5% 4 3 3 4 5% 21%	2533
December	1st to 10th	Night	17% 25% 8% 14% 6% 4 3 2 3 4 14%	2660
	11th to 20th	Night	17% 22% 8% 13% 6% 4 4 3 4 4 14%	3279
	21st to end	Night	26% 22% 7% 10% 5% 3 3 3 3 4 12%	4884

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	81% 4 8% 5% 1	2528
	11th to 20th	Day	85% 4 7% 4 1	2530
	21st to end	Day	83% 4 7% 4 2	2783
February	1st to 10th	Day	71% 5% 8% 14% 3	1718
	11th to 20th	Day	68% 5% 9% 13% 5%	1858
	21st to end	Day	63% 6% 12% 13% 5%	1570
March	1st to 10th	Day	50% 8% 13% 20% 8%	3120
	11th to 20th	Day	48% 6% 15% 20% 9% 1	3342
	21st to end	Day	56% 6% 10% 19% 8% 1	4027
April	1st to 10th	Day	53% 5% 9% 21% 11%	2280
	11th to 20th	Day	48% 6% 9% 20% 15% 2	2286
	21st to end	Day	47% 5% 12% 20% 14% 2	2470
May	1st to 10th	Day	40% 7% 11% 25% 16% 2	4120
	11th to 20th	Day	38% 5% 15% 23% 16% 3	4195
	21st to end	Day	32% 8% 12% 24% 22% 2	4837
June	1st to 10th	Day	35% 6% 12% 28% 17% 2	2660
	11th to 20th	Day	33% 6% 14% 24% 22% 1	2660
	21st to end	Day	34% 8% 14% 26% 16% 2	2660
July	1st to 10th	Day	40% 6% 13% 24% 14% 3	4371
	11th to 20th	Day	24% 6% 16% 33% 19% 2	4365
	21st to end	Day	30% 8% 15% 23% 22% 2	4662
August	1st to 10th	Day	35% 7% 12% 31% 14% 1	4216
	11th to 20th	Day	31% 7% 12% 33% 16% 1	4083
	21st to end	Day	33% 7% 15% 25% 17% 2	4180
September	1st to 10th	Day	35% 7% 13% 29% 14% 2	2275
	11th to 20th	Day	33% 6% 12% 32% 15% 2	2090
	21st to end	Day	40% 7% 12% 26% 15%	2090
October	1st to 10th	Day	29% 4 9% 39% 18% 1	3480
	11th to 20th	Day	44% 6% 13% 25% 11%	3008
	21st to end	Day	51% 6% 16% 19% 8%	3081
November	1st to 10th	Day	51% 6% 13% 20% 10%	1762
	11th to 20th	Day	67% 3 12% 13% 5%	1800
	21st to end	Day	68% 4 14% 11% 3	1737
December	1st to 10th	Day	77% 3 8% 9% 2	1520
	11th to 20th	Day	77% 4 12% 6% 1	1915
	21st to end	Day	80% 4 8% 7% 1	2783
January	1st to 10th	Night	78% 3 8% 9% 2	4428
	11th to 20th	Night	84% 3 6% 4 1	4440
	21st to end	Night	83% 4 8% 4 1	4884
February	1st to 10th	Night	71% 3 8% 12% 5%	2456
	11th to 20th	Night	67% 3 9% 16% 5%	2219
	21st to end	Night	62% 5% 14% 13% 7% 1	1884
March	1st to 10th	Night	49% 5% 14% 24% 7% 1	3733
	11th to 20th	Night	40% 5% 15% 26% 12% 2	3618
	21st to end	Night	57% 5% 10% 18% 9% 1	3633
April	1st to 10th	Night	49% 5% 10% 21% 13% 1	1900
	11th to 20th	Night	50% 5% 7% 19% 17% 3	1842
	21st to end	Night	45% 5% 11% 22% 13% 4	1710
May	1st to 10th	Night	46% 5% 13% 18% 15% 3	2840
	11th to 20th	Night	43% 6% 10% 24% 14% 4	2705
	21st to end	Night	45% 6% 8% 18% 19% 4	2751
June	1st to 10th	Night	35% 6% 13% 28% 15% 3	1520
	11th to 20th	Night	34% 6% 13% 26% 20% 2	1520
	21st to end	Night	35% 6% 15% 25% 16% 3	1520
July	1st to 10th	Night	40% 6% 11% 23% 12% 7%	2490
	11th to 20th	Night	27% 6% 14% 29% 22% 3	2482
	21st to end	Night	33% 6% 12% 21% 26% 2	2662
August	1st to 10th	Night	31% 6% 14% 28% 20% 1	2693
	11th to 20th	Night	32% 6% 11% 32% 18% 1	2812
	21st to end	Night	33% 7% 11% 25% 21% 2	3471
September	1st to 10th	Night	33% 6% 13% 27% 18% 2	1900
	11th to 20th	Night	30% 4 11% 35% 18% 1	2074
	21st to end	Night	42% 5% 12% 27% 12% 1	2090
October	1st to 10th	Night	31% 4 9% 33% 20% 1	3480
	11th to 20th	Night	40% 4 14% 25% 15%	3907
	21st to end	Night	45% 4 12% 27% 13%	4467
November	1st to 10th	Night	50% 5% 12% 20% 12% 1	2536
	11th to 20th	Night	64% 4 12% 13% 6% 1	2600
	21st to end	Night	66% 4 15% 13% 2	2533
December	1st to 10th	Night	76% 4 9% 9% 3	2660
	11th to 20th	Night	74% 4 12% 7% 2	3281
	21st to end	Night	77% 5% 11% 6% 2	4884

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	21% 19% 36% 19% 3 2	270
	11th to 20th	Day	27% 16% 37% 14% 4 1	270
	21st to end	Day	27% 18% 35% 16% 4	297
February	1st to 10th	Day	23% 26% 31% 14% 4 2	270
	11th to 20th	Day	20% 30% 35% 13% 1	270
	21st to end	Day	29% 27% 35% 8% 1	225
March	1st to 10th	Day	22% 30% 38% 8% 2	270
	11th to 20th	Day	23% 18% 32% 18% 8%	374
	21st to end	Day	29% 14% 31% 19% 6% 1	506
April	1st to 10th	Day	27% 17% 32% 19% 5%	460
	11th to 20th	Day	27% 25% 24% 15% 6% 2	452
	21st to end	Day	25% 15% 32% 19% 8% 1	460
May	1st to 10th	Day	20% 18% 34% 20% 6% 2	463
	11th to 20th	Day	19% 13% 30% 24% 10% 3	545
	21st to end	Day	15% 11% 31% 26% 13% 4	734
June	1st to 10th	Day	11% 10% 38% 28% 9% 4	680
	11th to 20th	Day	15% 10% 33% 29% 10% 4	680
	21st to end	Day	15% 9% 37% 26% 10% 4	680
July	1st to 10th	Day	8% 6% 30% 33% 17% 6%	671
	11th to 20th	Day	7% 9% 30% 33% 15% 6%	668
	21st to end	Day	8% 6% 31% 32% 18% 5%	739
August	1st to 10th	Day	10% 6% 26% 28% 22% 7%	562
	11th to 20th	Day	11% 5% 22% 32% 22% 9%	479
	21st to end	Day	12% 6% 25% 32% 18% 7%	539
September	1st to 10th	Day	13% 9% 27% 28% 18% 6%	490
	11th to 20th	Day	9% 6% 23% 27% 28% 7%	490
	21st to end	Day	15% 13% 24% 27% 15% 6%	490
October	1st to 10th	Day	19% 13% 24% 26% 16% 3	490
	11th to 20th	Day	26% 19% 32% 20% 3	352
	21st to end	Day	35% 16% 31% 14% 2 2	330
November	1st to 10th	Day	28% 18% 32% 15% 4 2	300
	11th to 20th	Day	26% 23% 38% 10% 3	300
	21st to end	Day	30% 18% 39% 11% 2	282
December	1st to 10th	Day	29% 23% 28% 16% 4	270
	11th to 20th	Day	26% 26% 31% 14% 3 1	270
	21st to end	Day	27% 25% 34% 11% 2	297
January	1st to 10th	Night	23% 16% 32% 22% 6%	950
	11th to 20th	Night	25% 16% 31% 22% 5% 1	950
	21st to end	Night	23% 11% 33% 27% 6%	1045
February	1st to 10th	Night	20% 17% 34% 25% 4 1	836
	11th to 20th	Night	21% 15% 34% 24% 5%	743
	21st to end	Night	24% 18% 35% 20% 3	628
March	1st to 10th	Night	21% 13% 32% 25% 9% 1	760
	11th to 20th	Night	19% 13% 35% 25% 8% 1	760
	21st to end	Night	21% 10% 29% 30% 9%	729
April	1st to 10th	Night	20% 11% 33% 29% 6% 1	570
	11th to 20th	Night	27% 11% 30% 24% 7% 1	563
	21st to end	Night	21% 11% 32% 26% 10% 1	570
May	1st to 10th	Night	19% 6% 33% 33% 8% 1	570
	11th to 20th	Night	19% 7% 30% 31% 13% 1	561
	21st to end	Night	14% 6% 26% 34% 19% 2	617
June	1st to 10th	Night	12% 6% 26% 41% 14% 1	570
	11th to 20th	Night	13% 5% 31% 33% 18% 1	570
	21st to end	Night	11% 6% 23% 39% 20% 2	570
July	1st to 10th	Night	9% 2 19% 39% 28% 4	555
	11th to 20th	Night	7% 3 21% 38% 29% 2	552
	21st to end	Night	9% 2 18% 40% 29% 1	624
August	1st to 10th	Night	8% 2 18% 41% 28% 3	567
	11th to 20th	Night	12% 2 15% 39% 28% 5%	564
	21st to end	Night	10% 3 18% 41% 25% 3	627
September	1st to 10th	Night	11% 5% 19% 38% 23% 5%	570
	11th to 20th	Night	11% 6% 20% 33% 25% 5%	744
	21st to end	Night	15% 10% 23% 29% 18% 5%	760
October	1st to 10th	Night	19% 6% 24% 32% 18% 1	760
	11th to 20th	Night	28% 11% 27% 23% 10% 1	760
	21st to end	Night	29% 11% 29% 23% 7%	836
November	1st to 10th	Night	23% 12% 31% 24% 9% 1	780
	11th to 20th	Night	28% 16% 31% 20% 5%	800
	21st to end	Night	28% 14% 30% 23% 4	783
December	1st to 10th	Night	27% 17% 32% 20% 4	950
	11th to 20th	Night	28% 15% 32% 20% 3 1	950
	21st to end	Night	32% 14% 34% 18% 2	1045

Page generated at 2024-11-22 08:02:27. Version ac07

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