Michigan City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Michigan City clear sky chart from 2005-11-06 to 2024-11-04.

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	13% 10% 4 8% 5% 4 4 4 5% 7% 36%	101216
	Night	15% 12% 5% 8% 5% 4 4 3 5% 6% 33%	97862
Transparency	Day	25% 48% 7% 13% 7% 1	104800
	Night	28% 47% 6% 11% 7% 1	102406
Seeing	Day	17% 12% 29% 25% 13% 4	15767
	Night	19% 11% 29% 27% 12% 1	25602

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% 19% 13% 13% 6% 6% 4 3 4 5% 14%	2527
	11th to 20th	Day	13% 19% 9% 16% 8% 5% 5% 9% 3 3 8%	2530
	21st to end	Day	23% 25% 6% 9% 5% 4 3 2 3 5% 15%	2783
February	1st to 10th	Day	15% 18% 5% 11% 6% 6% 4 3 4 6% 22%	1814
	11th to 20th	Day	14% 13% 4 13% 9% 4 3 4 4 4 28%	1848
	21st to end	Day	15% 16% 6% 12% 4 3 5% 3 3 6% 27%	1570
March	1st to 10th	Day	18% 13% 6% 8% 4 3 4 3 5% 6% 30%	3120
	11th to 20th	Day	10% 8% 6% 9% 6% 4 5% 3 6% 7% 35%	3303
	21st to end	Day	18% 11% 7% 11% 5% 5% 5% 3 5% 5% 25%	4091
April	1st to 10th	Day	16% 12% 3 7% 5% 4 4 3 5% 7% 34%	2280
	11th to 20th	Day	15% 11% 3 6% 4 4 4 3 5% 6% 38%	2254
	21st to end	Day	18% 9% 3 7% 4 4 4 4 6% 8% 33%	2441
May	1st to 10th	Day	17% 8% 2 6% 4 4 5% 4 6% 8% 35%	4082
	11th to 20th	Day	14% 8% 2 5% 3 4 5% 4 5% 8% 42%	4134
	21st to end	Day	9% 7% 3 6% 3 4 4 4 6% 9% 45%	4824
June	1st to 10th	Day	10% 5% 2 7% 4 4 5% 3 5% 8% 45%	2660
	11th to 20th	Day	8% 5% 2 5% 5% 5% 4 4 7% 9% 46%	2660
	21st to end	Day	11% 6% 3 5% 4 4 6% 4 7% 8% 43%	2660
July	1st to 10th	Day	12% 7% 3 7% 5% 5% 5% 4 6% 9% 38%	4440
	11th to 20th	Day	7% 4 2 5% 3 4 5% 4 6% 10% 50%	4440
	21st to end	Day	7% 6% 2 7% 5% 4 5% 4 7% 8% 45%	4813
August	1st to 10th	Day	10% 6% 2 5% 4 4 4 3 6% 8% 49%	4199
	11th to 20th	Day	10% 5% 2 6% 4 4 4 3 5% 7% 49%	3885
	21st to end	Day	7% 4 2 6% 4 4 5% 4 6% 8% 50%	4180
September	1st to 10th	Day	10% 5% 3 5% 5% 4 5% 4 5% 7% 46%	2280
	11th to 20th	Day	11% 5% 2 5% 3 5% 4 4 6% 6% 48%	2104
	21st to end	Day	12% 8% 2 7% 4 4 5% 4 5% 8% 41%	2090
October	1st to 10th	Day	14% 8% 2 6% 4 4 4 3 5% 6% 45%	2090
	11th to 20th	Day	20% 10% 2 7% 5% 4 4 4 5% 6% 34%	1863
	21st to end	Day	22% 11% 4 8% 5% 5% 4 4 5% 6% 26%	1881
November	1st to 10th	Day	14% 12% 3 7% 3 4 4 3 5% 7% 37%	1699
	11th to 20th	Day	17% 16% 5% 9% 5% 4 4 3 5% 6% 25%	1710
	21st to end	Day	19% 16% 5% 10% 5% 4 4 3 3 5% 26%	1710
December	1st to 10th	Day	15% 20% 8% 12% 7% 5% 3 2 3 5% 21%	1550
	11th to 20th	Day	14% 20% 9% 12% 5% 3 4 3 5% 5% 20%	1918
	21st to end	Day	20% 22% 7% 16% 5% 5% 4 2 3 3 11%	2783
January	1st to 10th	Night	16% 20% 10% 13% 6% 4 4 3 4 4 17%	4428
	11th to 20th	Night	15% 21% 9% 16% 5% 4 5% 6% 4 3 10%	4440
	21st to end	Night	24% 21% 8% 11% 6% 4 4 2 4 4 12%	4884
February	1st to 10th	Night	17% 16% 5% 9% 7% 5% 4 3 4 5% 23%	2360
	11th to 20th	Night	14% 13% 5% 9% 8% 5% 6% 3 5% 6% 27%	2218
	21st to end	Night	19% 15% 4 11% 5% 4 3 3 4 4 28%	1884
March	1st to 10th	Night	17% 12% 5% 9% 5% 4 4 3 5% 5% 32%	3733
	11th to 20th	Night	9% 8% 4 8% 5% 5% 4 3 5% 6% 42%	3655
	21st to end	Night	20% 13% 7% 9% 5% 4 4 4 5% 6% 26%	3571
April	1st to 10th	Night	14% 12% 2 7% 5% 4 4 3 5% 7% 37%	1900
	11th to 20th	Night	19% 10% 2 6% 5% 4 4 4 5% 5% 38%	1875
	21st to end	Night	17% 8% 3 8% 6% 5% 4 3 5% 5% 36%	1738
May	1st to 10th	Night	17% 8% 3 7% 5% 5% 4 4 5% 8% 34%	2813
	11th to 20th	Night	18% 7% 2 6% 4 4 4 3 5% 8% 40%	2759
	21st to end	Night	14% 7% 2 6% 4 4 4 3 5% 5% 44%	2743
June	1st to 10th	Night	9% 5% 2 5% 4 4 3 4 6% 9% 48%	1520
	11th to 20th	Night	8% 5% 3 6% 5% 5% 5% 4 7% 8% 45%	1520
	21st to end	Night	9% 5% 3 7% 5% 5% 5% 5% 6% 8% 41%	1520
July	1st to 10th	Night	10% 5% 2 6% 5% 5% 6% 5% 7% 10% 41%	2530
	11th to 20th	Night	8% 4 2 5% 3 3 4 4 6% 7% 53%	2530
	21st to end	Night	6% 5% 2 6% 5% 4 5% 5% 9% 9% 45%	2750
August	1st to 10th	Night	9% 6% 2 7% 4 5% 4 4 7% 8% 45%	2731
	11th to 20th	Night	8% 5% 2 6% 4 4 4 4 5% 7% 51%	2940
	21st to end	Night	10% 4 2 5% 4 5% 4 3 5% 7% 51%	3476
September	1st to 10th	Night	11% 6% 3 5% 4 4 4 3 5% 7% 49%	1900
	11th to 20th	Night	11% 4 2 5% 3 3 4 3 5% 9% 52%	2056
	21st to end	Night	12% 6% 2 6% 4 5% 4 3 5% 8% 44%	2090
October	1st to 10th	Night	13% 6% 2 6% 4 4 4 3 5% 6% 48%	2090
	11th to 20th	Night	20% 10% 3 6% 3 3 3 3 5% 6% 38%	2310
	21st to end	Night	23% 11% 3 6% 4 3 4 3 4 6% 33%	2717
November	1st to 10th	Night	15% 13% 4 8% 4 3 4 3 5% 5% 38%	2452
	11th to 20th	Night	14% 19% 5% 10% 4 4 4 3 5% 6% 26%	2470
	21st to end	Night	19% 16% 5% 10% 5% 2 4 3 4 6% 27%	2470
December	1st to 10th	Night	17% 21% 8% 10% 6% 4 3 3 4 5% 19%	2626
	11th to 20th	Night	14% 20% 9% 13% 7% 4 4 4 4 5% 18%	3279
	21st to end	Night	23% 21% 7% 11% 6% 5% 4 3 4 5% 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	48% 40% 6% 4 1	2528
	11th to 20th	Day	49% 41% 7% 3	2530
	21st to end	Day	46% 40% 6% 7% 1	2783
February	1st to 10th	Day	23% 65% 5% 5% 3	1814
	11th to 20th	Day	21% 64% 4 7% 4	1858
	21st to end	Day	19% 65% 6% 8% 2 1	1570
March	1st to 10th	Day	33% 42% 8% 11% 6% 1	3120
	11th to 20th	Day	25% 43% 8% 20% 4	3303
	21st to end	Day	37% 43% 10% 8% 2	4091
April	1st to 10th	Day	20% 66% 4 7% 3	2280
	11th to 20th	Day	15% 66% 4 8% 5% 1	2254
	21st to end	Day	16% 66% 4 6% 6% 1	2441
May	1st to 10th	Day	26% 44% 8% 16% 6% 1	4120
	11th to 20th	Day	22% 42% 10% 20% 6%	4138
	21st to end	Day	18% 41% 8% 15% 17% 1	4837
June	1st to 10th	Day	12% 66% 3 9% 8% 1	2660
	11th to 20th	Day	15% 66% 5% 8% 5% 1	2660
	21st to end	Day	13% 65% 6% 11% 5% 1	2660
July	1st to 10th	Day	31% 39% 9% 12% 8% 2	4371
	11th to 20th	Day	16% 38% 12% 24% 9%	4365
	21st to end	Day	24% 38% 11% 10% 15% 2	4662
August	1st to 10th	Day	21% 39% 10% 21% 10%	4184
	11th to 20th	Day	22% 39% 7% 23% 9%	3924
	21st to end	Day	21% 40% 9% 16% 13% 1	4179
September	1st to 10th	Day	14% 62% 6% 10% 7% 1	2280
	11th to 20th	Day	12% 61% 5% 12% 8% 1	2104
	21st to end	Day	19% 61% 4 9% 6% 1	2090
October	1st to 10th	Day	15% 37% 5% 25% 16% 1	3480
	11th to 20th	Day	21% 39% 7% 15% 18%	3066
	21st to end	Day	31% 37% 5% 18% 7% 1	3081
November	1st to 10th	Day	22% 60% 6% 6% 6% 1	1699
	11th to 20th	Day	25% 61% 3 6% 5%	1710
	21st to end	Day	28% 60% 5% 5% 2	1710
December	1st to 10th	Day	28% 60% 5% 4 3	1550
	11th to 20th	Day	33% 48% 8% 9% 2	1915
	21st to end	Day	54% 38% 4 4 1	2783
January	1st to 10th	Night	46% 40% 7% 5% 1	4428
	11th to 20th	Night	51% 40% 5% 3 1	4440
	21st to end	Night	47% 40% 5% 6% 1	4884
February	1st to 10th	Night	23% 65% 4 5% 3	2360
	11th to 20th	Night	21% 63% 4 8% 4	2219
	21st to end	Night	21% 64% 3 8% 3 1	1884
March	1st to 10th	Night	31% 43% 7% 14% 5% 1	3733
	11th to 20th	Night	24% 42% 6% 17% 11% 1	3655
	21st to end	Night	35% 43% 7% 11% 3	3571
April	1st to 10th	Night	18% 65% 5% 7% 4	1900
	11th to 20th	Night	17% 66% 4 6% 5% 1	1875
	21st to end	Night	17% 66% 3 6% 6% 1	1738
May	1st to 10th	Night	28% 43% 6% 13% 9% 1	2840
	11th to 20th	Night	25% 42% 9% 19% 4	2760
	21st to end	Night	25% 42% 5% 8% 18% 3	2751
June	1st to 10th	Night	12% 66% 4 11% 7%	1520
	11th to 20th	Night	16% 65% 5% 8% 6% 1	1520
	21st to end	Night	13% 65% 5% 10% 6% 1	1520
July	1st to 10th	Night	28% 39% 9% 15% 5% 4	2490
	11th to 20th	Night	18% 38% 8% 14% 20% 1	2482
	21st to end	Night	22% 39% 11% 11% 15% 3	2662
August	1st to 10th	Night	23% 40% 9% 19% 9%	2722
	11th to 20th	Night	22% 40% 8% 18% 13%	2967
	21st to end	Night	22% 39% 7% 19% 12%	3476
September	1st to 10th	Night	12% 61% 6% 10% 10% 1	1900
	11th to 20th	Night	10% 61% 3 13% 12% 1	2056
	21st to end	Night	17% 61% 5% 10% 6%	2090
October	1st to 10th	Night	12% 37% 7% 25% 18% 1	3480
	11th to 20th	Night	27% 37% 3 12% 20%	3833
	21st to end	Night	25% 37% 6% 17% 15% 1	4467
November	1st to 10th	Night	26% 58% 4 7% 4 1	2452
	11th to 20th	Night	24% 60% 3 7% 5% 1	2470
	21st to end	Night	27% 60% 5% 6% 2	2470
December	1st to 10th	Night	28% 60% 4 5% 2	2626
	11th to 20th	Night	36% 50% 7% 6% 2	3281
	21st to end	Night	49% 37% 7% 4 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% 18% 37% 19% 3 1	270
	11th to 20th	Day	27% 17% 36% 16% 3 1	270
	21st to end	Day	27% 16% 38% 16% 2	297
February	1st to 10th	Day	21% 26% 34% 14% 5%	270
	11th to 20th	Day	23% 24% 33% 17% 3	270
	21st to end	Day	22% 26% 38% 12% 1	225
March	1st to 10th	Day	21% 24% 38% 14% 3	270
	11th to 20th	Day	22% 18% 34% 20% 5% 1	348
	21st to end	Day	27% 17% 31% 18% 6%	506
April	1st to 10th	Day	22% 16% 35% 20% 5% 1	460
	11th to 20th	Day	20% 22% 29% 19% 7% 4	452
	21st to end	Day	22% 15% 36% 18% 8% 1	460
May	1st to 10th	Day	24% 10% 34% 21% 9% 2	463
	11th to 20th	Day	20% 8% 32% 23% 14% 2	514
	21st to end	Day	13% 7% 31% 29% 15% 5%	734
June	1st to 10th	Day	11% 8% 28% 33% 17% 4	680
	11th to 20th	Day	10% 6% 33% 31% 16% 3	680
	21st to end	Day	13% 8% 30% 31% 14% 4	680
July	1st to 10th	Day	10% 5% 23% 29% 22% 11%	671
	11th to 20th	Day	9% 4 25% 33% 20% 8%	668
	21st to end	Day	8% 4 24% 39% 19% 5%	739
August	1st to 10th	Day	8% 3 18% 31% 28% 12%	543
	11th to 20th	Day	9% 4 26% 28% 26% 8%	479
	21st to end	Day	11% 3 18% 34% 28% 7%	539
September	1st to 10th	Day	12% 6% 21% 30% 24% 6%	490
	11th to 20th	Day	9% 6% 18% 30% 26% 10%	490
	21st to end	Day	16% 12% 22% 24% 19% 6%	490
October	1st to 10th	Day	16% 9% 28% 29% 16% 3	490
	11th to 20th	Day	23% 17% 30% 22% 7%	333
	21st to end	Day	29% 17% 34% 16% 3	330
November	1st to 10th	Day	16% 19% 35% 20% 8% 2	279
	11th to 20th	Day	24% 19% 33% 17% 6%	270
	21st to end	Day	28% 14% 40% 16% 2	270
December	1st to 10th	Day	19% 26% 34% 14% 7%	270
	11th to 20th	Day	19% 26% 37% 14% 4	270
	21st to end	Day	24% 25% 37% 13% 1	297
January	1st to 10th	Night	24% 18% 36% 19% 3	950
	11th to 20th	Night	25% 17% 37% 17% 3 1	950
	21st to end	Night	24% 15% 36% 22% 3	1045
February	1st to 10th	Night	26% 12% 37% 20% 4	825
	11th to 20th	Night	23% 16% 35% 21% 5%	743
	21st to end	Night	25% 18% 36% 16% 3	628
March	1st to 10th	Night	21% 16% 35% 21% 6% 1	760
	11th to 20th	Night	17% 11% 39% 25% 7%	760
	21st to end	Night	26% 9% 31% 27% 7%	693
April	1st to 10th	Night	19% 15% 34% 24% 6% 1	570
	11th to 20th	Night	23% 11% 30% 26% 9% 1	563
	21st to end	Night	20% 9% 33% 27% 9% 1	570
May	1st to 10th	Night	21% 7% 31% 30% 11% 1	570
	11th to 20th	Night	20% 4 26% 33% 16% 1	561
	21st to end	Night	12% 5% 23% 36% 22% 2	617
June	1st to 10th	Night	10% 4 23% 40% 22% 1	570
	11th to 20th	Night	9% 4 27% 40% 18% 2	570
	21st to end	Night	11% 4 26% 38% 20% 2	570
July	1st to 10th	Night	9% 1 14% 39% 30% 6%	555
	11th to 20th	Night	9% 3 20% 36% 27% 5%	552
	21st to end	Night	6% 1 17% 44% 30% 2	624
August	1st to 10th	Night	7% 2 12% 43% 32% 4	567
	11th to 20th	Night	7% 3 17% 39% 29% 5%	564
	21st to end	Night	10% 3 17% 38% 28% 4	627
September	1st to 10th	Night	13% 5% 18% 36% 25% 4	570
	11th to 20th	Night	11% 5% 16% 35% 28% 4	726
	21st to end	Night	13% 8% 25% 28% 22% 4	760
October	1st to 10th	Night	14% 8% 27% 30% 19% 1	760
	11th to 20th	Night	25% 13% 29% 25% 8%	760
	21st to end	Night	29% 14% 30% 22% 6%	836
November	1st to 10th	Night	23% 14% 32% 20% 10% 1	755
	11th to 20th	Night	23% 21% 31% 19% 5%	760
	21st to end	Night	27% 16% 32% 20% 5%	760
December	1st to 10th	Night	26% 19% 36% 16% 3	916
	11th to 20th	Night	23% 16% 37% 21% 3	950
	21st to end	Night	29% 18% 35% 16% 2	1045

Page generated at 2024-11-01 22:47:35. Version ac07

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