Manitowoc
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Manitowoc 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	12% 8% 3 7% 5% 5% 5% 4 6% 7% 38%	101618
	Night	14% 9% 3 7% 5% 4 4 4 5% 7% 38%	97944
Transparency	Day	42% 8% 14% 23% 12% 1	105150
	Night	45% 7% 13% 22% 13% 2	102553
Seeing	Day	15% 8% 27% 30% 17% 4	16011
	Night	17% 9% 28% 29% 15% 2	25879

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	13% 11% 5% 9% 5% 5% 5% 4 7% 7% 29%	2527
	11th to 20th	Day	13% 12% 5% 11% 5% 5% 8% 9% 6% 6% 20%	2530
	21st to end	Day	16% 17% 7% 10% 6% 4 4 3 4 6% 21%	2783
February	1st to 10th	Day	9% 12% 5% 10% 5% 4 5% 4 6% 7% 31%	1658
	11th to 20th	Day	12% 11% 4 8% 5% 4 4 4 6% 6% 36%	1848
	21st to end	Day	12% 11% 4 10% 5% 4 5% 4 5% 8% 33%	1570
March	1st to 10th	Day	12% 7% 3 7% 5% 4 4 3 4 7% 44%	3120
	11th to 20th	Day	11% 8% 4 7% 5% 5% 5% 4 6% 7% 40%	3260
	21st to end	Day	20% 11% 3 10% 5% 5% 4 3 5% 4 29%	4165
April	1st to 10th	Day	15% 12% 4 8% 5% 5% 5% 3 5% 6% 31%	2280
	11th to 20th	Day	18% 8% 3 7% 5% 5% 5% 4 5% 6% 35%	2254
	21st to end	Day	17% 9% 3 8% 5% 5% 4 4 5% 7% 35%	2454
May	1st to 10th	Day	14% 8% 3 6% 4 4 4 4 5% 6% 40%	4103
	11th to 20th	Day	12% 5% 3 7% 4 5% 5% 4 6% 7% 42%	4399
	21st to end	Day	12% 7% 3 7% 5% 4 5% 4 6% 7% 41%	4824
June	1st to 10th	Day	11% 6% 2 6% 5% 4 5% 5% 6% 8% 42%	2660
	11th to 20th	Day	13% 6% 2 5% 4 5% 5% 4 7% 10% 41%	2660
	21st to end	Day	9% 5% 2 7% 4 4 5% 4 7% 9% 44%	2660
July	1st to 10th	Day	12% 6% 2 6% 5% 4 5% 4 7% 10% 37%	4440
	11th to 20th	Day	5% 3 1 4 4 4 5% 4 7% 10% 51%	4440
	21st to end	Day	6% 5% 2 6% 4 5% 4 4 6% 9% 49%	4813
August	1st to 10th	Day	9% 5% 2 7% 4 5% 5% 4 6% 9% 44%	4405
	11th to 20th	Day	10% 5% 2 5% 4 4 5% 4 6% 8% 49%	3924
	21st to end	Day	9% 5% 2 6% 5% 5% 5% 4 6% 8% 44%	4180
September	1st to 10th	Day	11% 4 2 6% 5% 4 4 5% 6% 8% 45%	2280
	11th to 20th	Day	12% 4 2 6% 5% 4 4 3 5% 8% 47%	2151
	21st to end	Day	11% 6% 2 8% 5% 4 4 4 6% 7% 42%	2090
October	1st to 10th	Day	13% 7% 2 6% 4 4 4 3 6% 7% 44%	2042
	11th to 20th	Day	20% 8% 3 9% 6% 5% 5% 4 5% 7% 30%	1832
	21st to end	Day	16% 9% 3 8% 5% 5% 4 4 6% 7% 33%	1881
November	1st to 10th	Day	14% 8% 3 5% 5% 3 4 4 6% 8% 42%	1762
	11th to 20th	Day	11% 12% 4 8% 6% 5% 4 4 6% 7% 31%	1800
	21st to end	Day	17% 12% 3 7% 5% 4 4 3 5% 7% 33%	1602
December	1st to 10th	Day	15% 11% 4 8% 8% 5% 5% 3 6% 8% 26%	1520
	11th to 20th	Day	14% 11% 4 10% 6% 6% 6% 4 7% 7% 25%	1918
	21st to end	Day	20% 18% 7% 10% 6% 5% 5% 3 5% 5% 17%	2783
January	1st to 10th	Night	15% 15% 5% 8% 4 3 4 2 5% 6% 32%	4428
	11th to 20th	Night	12% 13% 5% 11% 7% 5% 7% 8% 7% 6% 19%	4440
	21st to end	Night	15% 18% 7% 10% 5% 4 4 3 4 6% 24%	4884
February	1st to 10th	Night	12% 13% 5% 8% 5% 5% 4 4 5% 5% 33%	2515
	11th to 20th	Night	11% 12% 4 7% 4 5% 4 4 6% 5% 37%	2218
	21st to end	Night	15% 14% 4 6% 3 4 4 3 5% 6% 36%	1884
March	1st to 10th	Night	15% 8% 3 6% 4 3 4 3 5% 7% 42%	3733
	11th to 20th	Night	10% 8% 3 7% 5% 4 5% 4 6% 7% 41%	3718
	21st to end	Night	18% 10% 4 9% 5% 5% 4 4 5% 5% 31%	3476
April	1st to 10th	Night	16% 11% 4 7% 4 4 3 3 5% 6% 35%	1900
	11th to 20th	Night	20% 8% 3 6% 4 3 3 3 5% 5% 40%	1875
	21st to end	Night	17% 8% 3 8% 5% 4 4 3 5% 6% 37%	1724
May	1st to 10th	Night	14% 7% 3 7% 5% 4 4 4 6% 6% 39%	2791
	11th to 20th	Night	13% 6% 2 8% 6% 4 4 4 6% 8% 39%	2506
	21st to end	Night	16% 7% 3 6% 4 4 4 3 5% 7% 39%	2743
June	1st to 10th	Night	11% 5% 2 5% 6% 4 5% 4 5% 7% 45%	1520
	11th to 20th	Night	11% 5% 2 6% 4 4 4 4 5% 9% 45%	1520
	21st to end	Night	8% 6% 2 6% 4 4 5% 4 6% 8% 46%	1520
July	1st to 10th	Night	13% 6% 2 6% 4 4 5% 5% 6% 7% 42%	2530
	11th to 20th	Night	4 3 1 5% 3 4 3 4 6% 10% 57%	2530
	21st to end	Night	6% 4 2 6% 4 4 4 4 6% 9% 51%	2750
August	1st to 10th	Night	10% 5% 2 6% 4 3 5% 3 6% 8% 46%	2534
	11th to 20th	Night	11% 4 2 5% 4 3 5% 3 5% 7% 50%	2903
	21st to end	Night	11% 4 2 5% 4 4 4 4 5% 7% 49%	3476
September	1st to 10th	Night	9% 5% 2 5% 3 4 4 4 5% 7% 53%	1900
	11th to 20th	Night	10% 4 2 4 3 4 4 3 5% 7% 54%	2009
	21st to end	Night	12% 6% 2 7% 4 4 4 3 5% 7% 44%	2090
October	1st to 10th	Night	14% 6% 2 5% 3 3 4 3 5% 6% 48%	2136
	11th to 20th	Night	17% 8% 2 7% 4 4 4 3 5% 7% 40%	2346
	21st to end	Night	19% 8% 3 7% 4 4 4 3 5% 7% 35%	2717
November	1st to 10th	Night	13% 8% 2 5% 4 4 4 3 5% 6% 46%	2536
	11th to 20th	Night	15% 11% 3 8% 5% 5% 4 3 6% 6% 35%	2600
	21st to end	Night	17% 10% 2 6% 5% 4 5% 4 5% 6% 37%	2669
December	1st to 10th	Night	15% 12% 4 9% 5% 5% 5% 4 6% 7% 27%	2660
	11th to 20th	Night	16% 13% 4 8% 5% 5% 6% 4 5% 6% 28%	3279
	21st to end	Night	22% 18% 5% 9% 5% 4 5% 3 5% 6% 20%	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	52% 11% 18% 14% 4	2528
	11th to 20th	Day	58% 12% 17% 11% 2	2530
	21st to end	Day	65% 7% 12% 13% 3	2783
February	1st to 10th	Day	52% 10% 16% 16% 6%	1658
	11th to 20th	Day	48% 8% 13% 19% 10% 1	1858
	21st to end	Day	50% 8% 13% 18% 9% 2	1570
March	1st to 10th	Day	40% 8% 14% 22% 14% 3	3120
	11th to 20th	Day	41% 5% 16% 23% 13% 2	3260
	21st to end	Day	57% 6% 10% 20% 6% 1	4165
April	1st to 10th	Day	51% 8% 12% 17% 11%	2280
	11th to 20th	Day	48% 7% 10% 20% 13% 2	2254
	21st to end	Day	48% 8% 12% 19% 12% 2	2454
May	1st to 10th	Day	41% 8% 10% 23% 16% 1	4141
	11th to 20th	Day	35% 7% 16% 27% 13% 1	4403
	21st to end	Day	40% 7% 11% 21% 17% 4	4837
June	1st to 10th	Day	35% 8% 12% 27% 15% 2	2660
	11th to 20th	Day	36% 8% 13% 26% 15% 1	2660
	21st to end	Day	34% 10% 15% 25% 15% 1	2660
July	1st to 10th	Day	40% 8% 14% 26% 11% 2	4371
	11th to 20th	Day	23% 9% 17% 34% 15% 2	4365
	21st to end	Day	30% 8% 16% 22% 21% 2	4662
August	1st to 10th	Day	35% 8% 14% 30% 12% 1	4390
	11th to 20th	Day	31% 8% 13% 35% 11% 1	3963
	21st to end	Day	35% 9% 16% 23% 16% 1	4179
September	1st to 10th	Day	36% 9% 13% 26% 14% 1	2280
	11th to 20th	Day	35% 8% 15% 29% 12% 1	2151
	21st to end	Day	39% 8% 13% 30% 9% 1	2090
October	1st to 10th	Day	23% 5% 10% 38% 23% 2	3393
	11th to 20th	Day	44% 6% 11% 23% 15%	3022
	21st to end	Day	41% 6% 13% 27% 12% 1	3081
November	1st to 10th	Day	40% 9% 13% 23% 13% 1	1762
	11th to 20th	Day	51% 9% 16% 17% 7% 1	1800
	21st to end	Day	53% 7% 15% 19% 5% 1	1602
December	1st to 10th	Day	58% 10% 14% 13% 5%	1520
	11th to 20th	Day	57% 7% 16% 13% 5% 2	1915
	21st to end	Day	70% 8% 9% 10% 4	2783
January	1st to 10th	Night	55% 7% 14% 15% 7% 1	4428
	11th to 20th	Night	61% 11% 15% 9% 3	4440
	21st to end	Night	62% 7% 14% 13% 4	4884
February	1st to 10th	Night	53% 7% 11% 18% 10% 1	2515
	11th to 20th	Night	48% 7% 13% 21% 10% 2	2219
	21st to end	Night	50% 6% 14% 18% 11% 1	1884
March	1st to 10th	Night	42% 6% 15% 27% 8% 2	3733
	11th to 20th	Night	41% 7% 12% 24% 16% 2	3718
	21st to end	Night	56% 5% 10% 19% 9% 2	3476
April	1st to 10th	Night	49% 6% 9% 19% 16% 1	1900
	11th to 20th	Night	46% 4 9% 22% 16% 4	1875
	21st to end	Night	47% 5% 11% 22% 13% 2	1724
May	1st to 10th	Night	42% 7% 14% 18% 17% 2	2818
	11th to 20th	Night	40% 8% 13% 24% 13% 2	2507
	21st to end	Night	43% 7% 10% 19% 14% 7%	2751
June	1st to 10th	Night	35% 8% 11% 29% 16% 1	1520
	11th to 20th	Night	35% 6% 12% 25% 19% 2	1520
	21st to end	Night	34% 8% 14% 25% 16% 3	1520
July	1st to 10th	Night	40% 7% 13% 23% 12% 5%	2490
	11th to 20th	Night	22% 6% 16% 35% 18% 2	2482
	21st to end	Night	30% 7% 14% 24% 23% 3	2662
August	1st to 10th	Night	33% 8% 13% 26% 19% 2	2525
	11th to 20th	Night	33% 7% 11% 31% 18%	2930
	21st to end	Night	34% 7% 13% 23% 20% 3	3476
September	1st to 10th	Night	31% 7% 12% 26% 22% 2	1900
	11th to 20th	Night	31% 7% 12% 34% 16% 1	2009
	21st to end	Night	40% 5% 11% 29% 14% 1	2090
October	1st to 10th	Night	27% 4 9% 38% 20% 1	3565
	11th to 20th	Night	36% 6% 15% 25% 16% 1	3895
	21st to end	Night	43% 5% 13% 23% 16%	4467
November	1st to 10th	Night	40% 7% 12% 24% 16% 2	2536
	11th to 20th	Night	51% 6% 15% 15% 11% 1	2600
	21st to end	Night	48% 7% 17% 21% 5% 1	2669
December	1st to 10th	Night	57% 8% 14% 16% 4	2660
	11th to 20th	Night	57% 8% 13% 13% 7% 1	3281
	21st to end	Night	67% 7% 10% 12% 4	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	16% 11% 36% 25% 11% 1	270
	11th to 20th	Day	20% 11% 37% 23% 7% 1	270
	21st to end	Day	20% 10% 33% 29% 7% 1	297
February	1st to 10th	Day	13% 18% 39% 24% 6% 1	270
	11th to 20th	Day	14% 17% 43% 20% 6%	270
	21st to end	Day	18% 14% 44% 22% 2	225
March	1st to 10th	Day	14% 17% 46% 18% 4	270
	11th to 20th	Day	19% 14% 29% 27% 10% 2	313
	21st to end	Day	23% 11% 31% 25% 8% 1	506
April	1st to 10th	Day	22% 10% 35% 25% 8%	460
	11th to 20th	Day	20% 13% 31% 23% 8% 3	452
	21st to end	Day	18% 9% 32% 26% 13% 2	460
May	1st to 10th	Day	18% 6% 34% 28% 11% 2	471
	11th to 20th	Day	15% 4 30% 35% 13% 3	675
	21st to end	Day	13% 4 24% 31% 22% 6%	734
June	1st to 10th	Day	11% 3 26% 36% 19% 4	680
	11th to 20th	Day	15% 3 24% 35% 20% 3	680
	21st to end	Day	11% 5% 21% 38% 22% 3	680
July	1st to 10th	Day	7% 2 16% 37% 31% 8%	671
	11th to 20th	Day	9% 2 20% 38% 25% 8%	668
	21st to end	Day	5% 2 19% 40% 27% 8%	739
August	1st to 10th	Day	7% 2 17% 39% 27% 8%	671
	11th to 20th	Day	11% 3 13% 31% 32% 10%	479
	21st to end	Day	14% 3 17% 29% 30% 7%	539
September	1st to 10th	Day	12% 6% 20% 32% 22% 8%	490
	11th to 20th	Day	11% 3 18% 33% 26% 9%	490
	21st to end	Day	15% 7% 24% 25% 24% 5%	490
October	1st to 10th	Day	17% 8% 23% 32% 16% 3	442
	11th to 20th	Day	21% 15% 25% 29% 8% 1	300
	21st to end	Day	19% 12% 38% 21% 8% 1	330
November	1st to 10th	Day	14% 14% 29% 29% 13% 1	300
	11th to 20th	Day	14% 15% 40% 22% 8%	300
	21st to end	Day	20% 12% 37% 25% 5%	282
December	1st to 10th	Day	19% 17% 38% 20% 6%	270
	11th to 20th	Day	23% 17% 40% 13% 6% 1	270
	21st to end	Day	26% 20% 34% 15% 5%	297
January	1st to 10th	Night	19% 14% 40% 21% 6%	950
	11th to 20th	Night	22% 13% 35% 24% 6%	950
	21st to end	Night	20% 10% 37% 25% 7%	1045
February	1st to 10th	Night	19% 13% 37% 24% 5% 1	947
	11th to 20th	Night	16% 15% 38% 23% 8%	743
	21st to end	Night	24% 12% 37% 23% 4 1	628
March	1st to 10th	Night	19% 9% 33% 27% 10% 1	760
	11th to 20th	Night	14% 9% 37% 29% 9% 1	760
	21st to end	Night	22% 6% 28% 32% 11% 1	637
April	1st to 10th	Night	20% 9% 34% 30% 7% 1	570
	11th to 20th	Night	22% 7% 27% 30% 12% 2	563
	21st to end	Night	20% 6% 26% 32% 15% 1	570
May	1st to 10th	Night	19% 3 26% 38% 13% 1	570
	11th to 20th	Night	18% 4 23% 37% 16% 2	561
	21st to end	Night	14% 3 18% 35% 24% 5%	617
June	1st to 10th	Night	11% 4 19% 43% 21% 2	570
	11th to 20th	Night	14% 2 20% 36% 25% 3	570
	21st to end	Night	10% 2 17% 41% 27% 3	570
July	1st to 10th	Night	9% 2 10% 39% 34% 6%	555
	11th to 20th	Night	6% 2 15% 39% 34% 5%	552
	21st to end	Night	5% 2 15% 41% 33% 4	624
August	1st to 10th	Night	9% 1 13% 41% 33% 4	567
	11th to 20th	Night	8% 2 14% 35% 33% 8%	564
	21st to end	Night	11% 2 17% 34% 32% 4	627
September	1st to 10th	Night	9% 4 21% 33% 26% 7%	570
	11th to 20th	Night	11% 6% 18% 30% 28% 7%	679
	21st to end	Night	16% 7% 22% 27% 23% 5%	760
October	1st to 10th	Night	16% 6% 27% 27% 21% 3	760
	11th to 20th	Night	23% 11% 28% 26% 12%	760
	21st to end	Night	24% 10% 29% 26% 10% 1	836
November	1st to 10th	Night	17% 10% 33% 29% 9% 1	780
	11th to 20th	Night	21% 15% 33% 23% 8% 1	800
	21st to end	Night	23% 13% 33% 24% 7%	919
December	1st to 10th	Night	22% 16% 37% 19% 6%	950
	11th to 20th	Night	23% 15% 35% 21% 6% 1	950
	21st to end	Night	27% 15% 35% 21% 3	1045

Page generated at 2024-11-22 07:02:25. Version ac07

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