Big Rapids
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Big Rapids clear sky chart from 2005-11-06 to 2024-11-05.

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% 5% 5% 4 5% 7% 33%	101307
	Night	14% 12% 4 9% 5% 5% 4 3 5% 6% 33%	97792
Transparency	Day	51% 3 11% 22% 13% 1	104865
	Night	52% 3 11% 22% 12% 1	102362
Seeing	Day	18% 15% 31% 22% 11% 3	15875
	Night	19% 11% 31% 28% 10% 1	25729

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% 24% 10% 14% 7% 6% 4 3 5% 4 11%	2527
	11th to 20th	Day	13% 17% 8% 19% 12% 11% 5% 3 3 3 6%	2530
	21st to end	Day	18% 22% 12% 13% 7% 5% 4 3 3 3 8%	2783
February	1st to 10th	Day	11% 14% 7% 11% 11% 7% 7% 4 4 5% 18%	1694
	11th to 20th	Day	10% 16% 7% 15% 10% 5% 5% 4 5% 5% 19%	1848
	21st to end	Day	12% 18% 7% 12% 6% 5% 5% 4 5% 5% 21%	1570
March	1st to 10th	Day	13% 14% 5% 9% 6% 4 4 4 4 6% 30%	3120
	11th to 20th	Day	10% 8% 7% 12% 6% 6% 5% 4 5% 7% 31%	3398
	21st to end	Day	20% 11% 6% 10% 5% 4 4 3 5% 4 28%	3941
April	1st to 10th	Day	17% 14% 4 7% 5% 4 4 4 5% 6% 29%	2280
	11th to 20th	Day	18% 11% 3 7% 5% 4 4 3 4 6% 34%	2330
	21st to end	Day	16% 11% 3 8% 6% 4 4 3 5% 7% 33%	2470
May	1st to 10th	Day	16% 8% 2 7% 4 4 4 4 5% 6% 39%	4082
	11th to 20th	Day	13% 8% 2 6% 4 4 4 4 7% 8% 40%	4135
	21st to end	Day	11% 6% 2 6% 5% 4 5% 4 6% 8% 43%	4824
June	1st to 10th	Day	12% 6% 2 6% 4 4 5% 4 5% 8% 43%	2660
	11th to 20th	Day	13% 6% 2 6% 4 5% 5% 4 7% 8% 42%	2660
	21st to end	Day	12% 6% 2 7% 5% 5% 5% 4 5% 7% 42%	2660
July	1st to 10th	Day	13% 7% 3 7% 5% 5% 5% 4 7% 8% 36%	4440
	11th to 20th	Day	6% 5% 2 5% 4 4 6% 4 6% 10% 47%	4440
	21st to end	Day	8% 5% 2 6% 5% 5% 5% 5% 6% 9% 44%	4813
August	1st to 10th	Day	11% 6% 3 7% 6% 5% 6% 5% 7% 8% 38%	4177
	11th to 20th	Day	13% 5% 2 5% 4 4 4 4 6% 6% 47%	4044
	21st to end	Day	9% 6% 2 6% 4 5% 5% 4 7% 8% 42%	4286
September	1st to 10th	Day	12% 5% 2 6% 5% 5% 6% 4 6% 8% 42%	2247
	11th to 20th	Day	12% 5% 2 5% 5% 5% 4 4 5% 7% 46%	2090
	21st to end	Day	14% 7% 3 7% 5% 5% 4 4 5% 7% 40%	2090
October	1st to 10th	Day	17% 8% 3 7% 4 4 4 3 4 6% 40%	2090
	11th to 20th	Day	21% 12% 3 7% 6% 6% 5% 3 4 6% 25%	1829
	21st to end	Day	21% 13% 3 9% 6% 5% 5% 4 5% 5% 23%	1881
November	1st to 10th	Day	13% 12% 3 8% 5% 5% 5% 3 5% 7% 33%	1708
	11th to 20th	Day	13% 19% 6% 12% 6% 6% 4 3 6% 6% 22%	1710
	21st to end	Day	20% 19% 6% 9% 5% 5% 3 2 4 5% 21%	1710
December	1st to 10th	Day	13% 21% 11% 13% 7% 4 5% 3 4 4 15%	1539
	11th to 20th	Day	14% 19% 7% 13% 8% 6% 5% 4 5% 6% 14%	1918
	21st to end	Day	23% 21% 8% 13% 6% 5% 4 3 4 4 9%	2783
January	1st to 10th	Night	14% 20% 11% 14% 5% 5% 4 3 4 4 16%	4428
	11th to 20th	Night	13% 17% 8% 18% 9% 12% 4 3 4 4 9%	4440
	21st to end	Night	18% 21% 8% 16% 6% 5% 4 3 4 5% 10%	4884
February	1st to 10th	Night	12% 15% 6% 12% 11% 6% 5% 4 4 5% 19%	2482
	11th to 20th	Night	12% 13% 6% 12% 9% 5% 6% 3 6% 5% 24%	2218
	21st to end	Night	15% 15% 5% 12% 6% 5% 4 3 4 6% 25%	1884
March	1st to 10th	Night	17% 8% 5% 8% 4 4 5% 3 5% 6% 37%	3733
	11th to 20th	Night	10% 10% 3 7% 4 5% 4 4 6% 7% 41%	3561
	21st to end	Night	15% 14% 5% 9% 5% 5% 4 3 5% 6% 29%	3704
April	1st to 10th	Night	16% 11% 4 7% 5% 4 4 3 5% 6% 35%	1900
	11th to 20th	Night	19% 10% 3 6% 4 3 3 3 5% 7% 36%	1798
	21st to end	Night	18% 9% 3 6% 3 4 4 3 6% 6% 37%	1710
May	1st to 10th	Night	13% 8% 3 6% 5% 6% 4 4 6% 8% 38%	2813
	11th to 20th	Night	15% 7% 2 6% 4 5% 4 3 6% 8% 40%	2759
	21st to end	Night	16% 7% 2 6% 4 3 3 3 4 6% 45%	2743
June	1st to 10th	Night	12% 7% 3 6% 4 4 3 3 7% 9% 44%	1520
	11th to 20th	Night	11% 6% 2 7% 3 3 3 5% 7% 9% 45%	1520
	21st to end	Night	9% 5% 3 5% 5% 4 4 5% 5% 8% 47%	1520
July	1st to 10th	Night	10% 7% 2 7% 5% 4 5% 4 6% 7% 42%	2530
	11th to 20th	Night	6% 4 2 4 3 4 4 4 5% 6% 58%	2530
	21st to end	Night	8% 5% 3 5% 4 4 4 4 5% 7% 52%	2750
August	1st to 10th	Night	11% 5% 2 6% 4 3 4 3 5% 10% 48%	2754
	11th to 20th	Night	11% 4 2 4 4 4 4 3 5% 7% 51%	2785
	21st to end	Night	10% 5% 1 6% 4 4 4 4 5% 8% 49%	3367
September	1st to 10th	Night	9% 4 2 5% 4 5% 4 3 6% 6% 52%	1913
	11th to 20th	Night	11% 5% 1 5% 3 3 5% 3 4 8% 53%	2090
	21st to end	Night	15% 6% 2 6% 4 4 4 3 5% 9% 42%	2090
October	1st to 10th	Night	17% 7% 2 5% 3 2 4 3 5% 6% 46%	2090
	11th to 20th	Night	19% 10% 3 7% 4 4 4 4 5% 7% 33%	2346
	21st to end	Night	22% 12% 4 6% 5% 5% 4 3 4 6% 31%	2717
November	1st to 10th	Night	12% 13% 3 8% 3 4 5% 4 5% 7% 36%	2470
	11th to 20th	Night	14% 15% 5% 11% 5% 5% 5% 5% 5% 7% 24%	2470
	21st to end	Night	17% 16% 6% 9% 5% 5% 4 4 4 6% 23%	2470
December	1st to 10th	Night	14% 18% 7% 14% 8% 6% 5% 4 4 5% 16%	2640
	11th to 20th	Night	15% 19% 7% 16% 6% 5% 4 4 5% 5% 15%	3279
	21st to end	Night	25% 23% 6% 12% 5% 4 3 2 4 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	78% 2 9% 9% 2	2528
	11th to 20th	Day	86% 3 4 6% 1	2530
	21st to end	Day	83% 1 7% 6% 2	2783
February	1st to 10th	Day	69% 3 7% 16% 5%	1694
	11th to 20th	Day	67% 3 7% 14% 8%	1858
	21st to end	Day	65% 3 10% 16% 5% 1	1570
March	1st to 10th	Day	57% 1 10% 22% 9% 1	3120
	11th to 20th	Day	56% 1 13% 18% 10% 2	3398
	21st to end	Day	60% 2 8% 19% 10% 1	3941
April	1st to 10th	Day	56% 3 9% 19% 12%	2280
	11th to 20th	Day	53% 2 9% 20% 14% 2	2330
	21st to end	Day	52% 3 11% 18% 15% 2	2470
May	1st to 10th	Day	48% 2 8% 22% 18% 2	4120
	11th to 20th	Day	43% 2 12% 26% 16% 2	4139
	21st to end	Day	41% 2 10% 22% 22% 2	4837
June	1st to 10th	Day	40% 3 10% 29% 17% 2	2660
	11th to 20th	Day	40% 3 12% 24% 20% 1	2660
	21st to end	Day	42% 4 12% 25% 16% 2	2660
July	1st to 10th	Day	45% 4 12% 22% 14% 3	4371
	11th to 20th	Day	31% 4 14% 32% 18% 2	4365
	21st to end	Day	35% 5% 13% 24% 21% 2	4662
August	1st to 10th	Day	42% 4 9% 28% 15% 1	4162
	11th to 20th	Day	36% 5% 11% 29% 18% 1	4083
	21st to end	Day	38% 5% 13% 27% 16% 1	4285
September	1st to 10th	Day	40% 4 13% 28% 14% 2	2247
	11th to 20th	Day	37% 3 12% 31% 15% 1	2090
	21st to end	Day	44% 3 12% 27% 14%	2090
October	1st to 10th	Day	33% 2 7% 34% 21% 3	3480
	11th to 20th	Day	48% 2 12% 25% 13%	3006
	21st to end	Day	56% 3 13% 20% 7%	3081
November	1st to 10th	Day	52% 3 12% 23% 10% 1	1708
	11th to 20th	Day	63% 3 12% 16% 5%	1710
	21st to end	Day	68% 2 12% 13% 4	1710
December	1st to 10th	Day	74% 2 8% 13% 2	1539
	11th to 20th	Day	71% 3 12% 11% 2	1915
	21st to end	Day	80% 2 7% 8% 3	2783
January	1st to 10th	Night	73% 2 7% 12% 5%	4428
	11th to 20th	Night	81% 2 6% 8% 3	4440
	21st to end	Night	78% 2 9% 8% 3	4884
February	1st to 10th	Night	68% 2 7% 15% 6% 1	2482
	11th to 20th	Night	61% 3 8% 18% 9% 1	2219
	21st to end	Night	61% 2 11% 17% 8% 1	1884
March	1st to 10th	Night	49% 2 15% 25% 8% 1	3733
	11th to 20th	Night	44% 1 15% 24% 15% 2	3561
	21st to end	Night	58% 1 10% 21% 9% 1	3704
April	1st to 10th	Night	51% 3 8% 22% 15% 1	1900
	11th to 20th	Night	49% 2 8% 22% 17% 2	1798
	21st to end	Night	48% 2 11% 22% 13% 4	1710
May	1st to 10th	Night	46% 2 11% 20% 17% 3	2840
	11th to 20th	Night	44% 2 8% 28% 16% 2	2760
	21st to end	Night	43% 2 9% 22% 20% 4	2751
June	1st to 10th	Night	37% 3 12% 28% 17% 2	1520
	11th to 20th	Night	36% 3 14% 24% 22% 1	1520
	21st to end	Night	35% 4 14% 29% 16% 2	1520
July	1st to 10th	Night	40% 4 11% 26% 13% 6%	2490
	11th to 20th	Night	26% 4 13% 33% 23% 2	2482
	21st to end	Night	32% 4 16% 23% 23% 2	2662
August	1st to 10th	Night	33% 3 13% 31% 18% 1	2745
	11th to 20th	Night	33% 3 12% 35% 17% 1	2812
	21st to end	Night	34% 4 12% 28% 19% 2	3367
September	1st to 10th	Night	33% 4 10% 32% 19% 2	1913
	11th to 20th	Night	32% 2 11% 37% 16% 1	2090
	21st to end	Night	40% 3 13% 30% 12% 1	2090
October	1st to 10th	Night	30% 3 10% 39% 17% 1	3480
	11th to 20th	Night	42% 4 12% 26% 17% 1	3895
	21st to end	Night	48% 2 11% 29% 10%	4467
November	1st to 10th	Night	49% 4 10% 24% 12% 1	2470
	11th to 20th	Night	60% 4 14% 17% 6% 1	2470
	21st to end	Night	63% 2 14% 16% 4 1	2470
December	1st to 10th	Night	71% 3 9% 12% 4	2640
	11th to 20th	Night	71% 3 12% 10% 4	3281
	21st to end	Night	77% 2 10% 8% 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	22% 17% 36% 20% 5% 1	270
	11th to 20th	Day	26% 20% 36% 13% 4	270
	21st to end	Day	23% 19% 36% 19% 4	297
February	1st to 10th	Day	17% 27% 34% 18% 3 1	270
	11th to 20th	Day	19% 31% 36% 12% 2	270
	21st to end	Day	26% 32% 32% 9% 1	225
March	1st to 10th	Day	24% 24% 39% 10% 3	270
	11th to 20th	Day	23% 17% 29% 23% 7% 1	404
	21st to end	Day	27% 17% 32% 18% 5% 1	506
April	1st to 10th	Day	25% 19% 33% 19% 4 1	460
	11th to 20th	Day	28% 20% 30% 13% 6% 2	452
	21st to end	Day	23% 16% 30% 21% 9% 1	460
May	1st to 10th	Day	23% 18% 31% 19% 6% 3	463
	11th to 20th	Day	19% 13% 31% 24% 10% 3	515
	21st to end	Day	14% 13% 31% 26% 12% 3	734
June	1st to 10th	Day	13% 13% 37% 25% 9% 3	680
	11th to 20th	Day	15% 12% 34% 27% 9% 4	680
	21st to end	Day	15% 13% 34% 25% 10% 3	680
July	1st to 10th	Day	9% 10% 29% 30% 17% 6%	671
	11th to 20th	Day	8% 11% 29% 29% 17% 7%	668
	21st to end	Day	9% 7% 32% 28% 16% 7%	739
August	1st to 10th	Day	10% 8% 28% 24% 22% 8%	534
	11th to 20th	Day	12% 6% 21% 28% 21% 11%	479
	21st to end	Day	14% 7% 24% 29% 19% 7%	539
September	1st to 10th	Day	14% 10% 24% 26% 18% 8%	490
	11th to 20th	Day	10% 7% 22% 28% 25% 8%	490
	21st to end	Day	18% 14% 21% 27% 16% 5%	490
October	1st to 10th	Day	20% 14% 29% 21% 14% 2	490
	11th to 20th	Day	26% 17% 31% 20% 5%	390
	21st to end	Day	31% 20% 31% 13% 4 2	330
November	1st to 10th	Day	23% 20% 33% 18% 5% 1	282
	11th to 20th	Day	20% 24% 39% 13% 3	270
	21st to end	Day	31% 22% 29% 13% 4	270
December	1st to 10th	Day	25% 26% 31% 13% 4	270
	11th to 20th	Day	24% 24% 37% 13% 2	270
	21st to end	Day	27% 25% 34% 11% 3 1	297
January	1st to 10th	Night	21% 19% 34% 20% 6% 1	950
	11th to 20th	Night	24% 15% 34% 22% 5%	950
	21st to end	Night	20% 11% 35% 28% 6%	1045
February	1st to 10th	Night	18% 16% 36% 26% 3	805
	11th to 20th	Night	21% 15% 37% 23% 3	743
	21st to end	Night	24% 19% 36% 19% 2	628
March	1st to 10th	Night	19% 14% 35% 24% 8% 1	760
	11th to 20th	Night	18% 15% 36% 23% 7% 1	760
	21st to end	Night	21% 13% 34% 25% 6%	774
April	1st to 10th	Night	21% 13% 35% 25% 5% 1	570
	11th to 20th	Night	27% 12% 31% 24% 5% 1	563
	21st to end	Night	21% 14% 33% 25% 7% 1	570
May	1st to 10th	Night	16% 12% 35% 29% 7% 1	570
	11th to 20th	Night	18% 8% 33% 30% 10% 1	561
	21st to end	Night	13% 8% 30% 31% 16% 1	617
June	1st to 10th	Night	13% 9% 31% 33% 12% 1	570
	11th to 20th	Night	12% 7% 29% 38% 13% 1	570
	21st to end	Night	11% 4 29% 41% 14% 1	570
July	1st to 10th	Night	7% 4 22% 42% 24% 3	555
	11th to 20th	Night	7% 6% 23% 42% 20% 2	552
	21st to end	Night	9% 3 25% 41% 22% 1	624
August	1st to 10th	Night	8% 3 23% 43% 21% 2	567
	11th to 20th	Night	10% 2 21% 39% 24% 4	564
	21st to end	Night	14% 3 21% 40% 20% 2	627
September	1st to 10th	Night	8% 6% 25% 36% 20% 4	583
	11th to 20th	Night	12% 6% 21% 36% 23% 3	760
	21st to end	Night	17% 9% 24% 31% 16% 3	760
October	1st to 10th	Night	20% 9% 24% 32% 14% 1	760
	11th to 20th	Night	24% 12% 30% 25% 7% 1	760
	21st to end	Night	29% 12% 31% 22% 6%	836
November	1st to 10th	Night	19% 14% 32% 27% 7% 1	760
	11th to 20th	Night	22% 16% 37% 20% 5%	760
	21st to end	Night	25% 14% 31% 25% 4	760
December	1st to 10th	Night	22% 18% 33% 23% 3	930
	11th to 20th	Night	25% 15% 37% 18% 4 1	950
	21st to end	Night	31% 14% 35% 19% 2	1045

Page generated at 2024-11-03 02:11:24. Version ac07

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