Spruce Woods Provincial Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Spruce Woods Provincial Park clear sky chart from 2005-11-06 to 2024-04-03.

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	11% 9% 4 8% 6% 4 5% 5% 6% 7% 35%	78322
	Night	10% 10% 4 8% 7% 4 5% 5% 5% 7% 35%	81780
Transparency	Day	47% 7% 14% 23% 8% 1	78035
	Night	48% 7% 14% 22% 9% 1	81647
Seeing	Day	15% 9% 31% 28% 14% 3	15280
	Night	14% 7% 32% 34% 12% 1	25454

By Month

Percentage Cloud Cover NW (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	5% 17% 7% 12% 9% 4 5% 5% 7% 7% 19%	2219
	11th to 20th	Day	4 9% 6% 13% 12% 9% 10% 8% 7% 8% 14%	2371
	21st to end	Day	9% 12% 5% 11% 7% 4 7% 5% 6% 6% 27%	2794
February	1st to 10th	Day	10% 11% 6% 11% 9% 5% 7% 6% 8% 7% 20%	1537
	11th to 20th	Day	6% 9% 5% 9% 10% 5% 7% 8% 6% 9% 25%	1679
	21st to end	Day	7% 10% 5% 10% 10% 5% 6% 7% 6% 6% 27%	1570
March	1st to 10th	Day	10% 12% 6% 11% 9% 5% 6% 5% 5% 8% 21%	1900
	11th to 20th	Day	7% 11% 5% 9% 9% 4 5% 5% 7% 7% 31%	2058
	21st to end	Day	13% 10% 5% 11% 7% 4 5% 4 5% 7% 29%	2332
April	1st to 10th	Day	10% 11% 4 7% 6% 3 5% 5% 6% 8% 35%	2207
	11th to 20th	Day	13% 11% 5% 9% 7% 4 5% 4 5% 6% 31%	2312
	21st to end	Day	15% 9% 4 7% 6% 4 4 5% 6% 7% 34%	2340
May	1st to 10th	Day	15% 8% 3 6% 5% 3 5% 4 5% 7% 39%	2381
	11th to 20th	Day	17% 8% 3 6% 5% 3 4 4 5% 8% 36%	2623
	21st to end	Day	21% 6% 3 5% 4 3 4 5% 5% 9% 35%	2918
June	1st to 10th	Day	14% 6% 2 5% 5% 4 5% 6% 6% 8% 37%	2700
	11th to 20th	Day	15% 6% 3 6% 6% 4 6% 5% 6% 8% 34%	2700
	21st to end	Day	12% 6% 2 6% 6% 3 5% 6% 7% 10% 37%	2700
July	1st to 10th	Day	8% 4 2 4 5% 4 5% 6% 7% 9% 47%	2700
	11th to 20th	Day	10% 5% 2 5% 5% 3 5% 6% 7% 9% 43%	2700
	21st to end	Day	6% 3 2 4 5% 3 5% 5% 6% 9% 52%	2787
August	1st to 10th	Day	8% 5% 3 5% 4 3 5% 5% 6% 8% 47%	2507
	11th to 20th	Day	10% 4 2 4 4 3 5% 6% 7% 9% 46%	2301
	21st to end	Day	12% 6% 2 5% 4 2 4 4 5% 7% 50%	2574
September	1st to 10th	Day	12% 5% 2 5% 4 3 4 4 5% 7% 50%	2199
	11th to 20th	Day	14% 6% 2 6% 6% 2 4 4 5% 7% 44%	1980
	21st to end	Day	15% 6% 2 6% 4 2 3 4 6% 7% 44%	1980
October	1st to 10th	Day	19% 11% 3 5% 5% 3 3 3 5% 6% 36%	1905
	11th to 20th	Day	14% 11% 3 6% 6% 3 4 3 5% 8% 37%	1674
	21st to end	Day	15% 13% 5% 8% 5% 3 5% 6% 5% 7% 28%	1782
November	1st to 10th	Day	18% 13% 6% 9% 6% 3 4 4 4 5% 29%	1614
	11th to 20th	Day	8% 14% 7% 11% 9% 3 4 3 4 6% 29%	1497
	21st to end	Day	10% 14% 5% 10% 9% 3 5% 5% 4 5% 29%	1330
December	1st to 10th	Day	8% 12% 7% 15% 11% 5% 7% 6% 4 7% 18%	1330
	11th to 20th	Day	10% 14% 8% 13% 10% 5% 5% 6% 6% 6% 18%	1679
	21st to end	Day	8% 10% 5% 10% 6% 3 5% 5% 5% 7% 37%	2442
January	1st to 10th	Night	6% 14% 7% 12% 9% 5% 7% 6% 6% 7% 21%	4737
	11th to 20th	Night	6% 10% 6% 13% 11% 6% 9% 8% 7% 7% 18%	4520
	21st to end	Night	8% 13% 7% 13% 8% 4 5% 5% 5% 6% 26%	4873
February	1st to 10th	Night	8% 12% 6% 10% 9% 4 7% 7% 5% 6% 27%	2642
	11th to 20th	Night	7% 9% 4 9% 6% 4 7% 7% 6% 7% 33%	2403
	21st to end	Night	7% 10% 5% 8% 8% 4 6% 5% 6% 8% 33%	1884
March	1st to 10th	Night	10% 11% 5% 10% 8% 4 6% 6% 5% 7% 27%	2280
	11th to 20th	Night	6% 10% 5% 7% 6% 4 5% 5% 5% 7% 40%	2119
	21st to end	Night	11% 11% 4 9% 6% 3 5% 4 5% 8% 34%	2263
April	1st to 10th	Night	7% 6% 4 6% 6% 4 5% 5% 6% 8% 42%	1797
	11th to 20th	Night	14% 13% 3 7% 7% 3 5% 4 5% 5% 34%	1599
	21st to end	Night	13% 9% 3 6% 6% 4 5% 5% 5% 7% 37%	1620
May	1st to 10th	Night	15% 6% 2 6% 6% 3 4 4 5% 6% 43%	1576
	11th to 20th	Night	14% 7% 2 5% 4 3 5% 4 6% 7% 42%	1273
	21st to end	Night	19% 6% 3 4 5% 3 3 4 4 8% 41%	1358
June	1st to 10th	Night	11% 6% 2 5% 3 3 4 6% 6% 9% 44%	1260
	11th to 20th	Night	11% 6% 2 5% 6% 4 4 5% 5% 8% 43%	1260
	21st to end	Night	10% 4 2 4 5% 3 6% 5% 8% 10% 43%	1260
July	1st to 10th	Night	8% 3 1 4 3 2 5% 4 5% 8% 58%	1260
	11th to 20th	Night	7% 3 2 3 3 3 4 6% 7% 9% 53%	1260
	21st to end	Night	6% 3 1 3 4 2 5% 5% 6% 8% 58%	1527
August	1st to 10th	Night	6% 4 2 4 5% 3 5% 5% 5% 8% 53%	1432
	11th to 20th	Night	7% 4 2 4 5% 3 5% 4 5% 10% 52%	1600
	21st to end	Night	12% 4 1 3 3 2 4 4 4 5% 56%	1782
September	1st to 10th	Night	8% 5% 2 4 4 2 4 5% 6% 8% 52%	1758
	11th to 20th	Night	13% 5% 3 4 4 3 4 3 6% 7% 49%	1980
	21st to end	Night	15% 6% 3 6% 4 3 4 4 5% 7% 43%	1980
October	1st to 10th	Night	14% 10% 3 6% 5% 3 4 4 5% 7% 39%	2036
	11th to 20th	Night	17% 8% 2 5% 5% 3 3 4 5% 7% 40%	2283
	21st to end	Night	11% 12% 5% 7% 6% 3 5% 4 5% 6% 35%	2574
November	1st to 10th	Night	12% 12% 5% 8% 6% 3 5% 5% 6% 7% 32%	2462
	11th to 20th	Night	9% 14% 7% 11% 8% 3 5% 4 4 7% 28%	2679
	21st to end	Night	11% 12% 6% 10% 8% 4 4 4 4 6% 31%	2850
December	1st to 10th	Night	8% 11% 5% 12% 9% 5% 6% 6% 7% 6% 25%	2850
	11th to 20th	Night	10% 14% 7% 13% 8% 4 5% 5% 5% 6% 21%	3518
	21st to end	Night	8% 9% 4 10% 7% 4 5% 5% 5% 6% 36%	5225

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	61% 8% 14% 14% 3	2219
	11th to 20th	Day	64% 9% 9% 15% 3	2394
	21st to end	Day	55% 7% 10% 22% 6%	2794
February	1st to 10th	Day	60% 7% 11% 16% 6%	1537
	11th to 20th	Day	53% 9% 12% 18% 9%	1688
	21st to end	Day	55% 7% 13% 18% 7%	1570
March	1st to 10th	Day	60% 8% 14% 13% 5%	1900
	11th to 20th	Day	50% 8% 13% 22% 7%	2060
	21st to end	Day	55% 7% 12% 20% 7%	2332
April	1st to 10th	Day	46% 6% 13% 24% 9% 1	2207
	11th to 20th	Day	54% 5% 12% 17% 11% 1	2312
	21st to end	Day	49% 7% 15% 19% 8% 1	2340
May	1st to 10th	Day	45% 5% 11% 25% 12% 1	2381
	11th to 20th	Day	46% 6% 11% 25% 11% 1	2627
	21st to end	Day	47% 7% 13% 23% 9% 1	2918
June	1st to 10th	Day	43% 8% 17% 22% 9% 1	2700
	11th to 20th	Day	46% 8% 15% 20% 9% 1	2700
	21st to end	Day	40% 10% 20% 24% 6% 1	2700
July	1st to 10th	Day	31% 9% 20% 30% 10%	2626
	11th to 20th	Day	35% 9% 17% 28% 11% 1	2619
	21st to end	Day	29% 8% 18% 34% 11%	2632
August	1st to 10th	Day	33% 9% 18% 30% 10% 1	2491
	11th to 20th	Day	32% 8% 20% 31% 8%	2301
	21st to end	Day	35% 6% 15% 32% 12%	2574
September	1st to 10th	Day	35% 5% 16% 31% 11% 2	2199
	11th to 20th	Day	40% 7% 16% 26% 10% 1	1980
	21st to end	Day	41% 6% 15% 30% 8%	1980
October	1st to 10th	Day	49% 5% 13% 24% 8%	1905
	11th to 20th	Day	47% 6% 13% 24% 9% 1	1674
	21st to end	Day	55% 8% 14% 16% 6%	1782
November	1st to 10th	Day	58% 4 12% 17% 7% 1	1614
	11th to 20th	Day	57% 5% 16% 16% 6%	1497
	21st to end	Day	56% 9% 14% 16% 5%	1330
December	1st to 10th	Day	64% 7% 13% 12% 4	1330
	11th to 20th	Day	64% 8% 11% 12% 4	1680
	21st to end	Day	46% 7% 12% 22% 12% 1	2442
January	1st to 10th	Night	59% 10% 10% 17% 5%	4737
	11th to 20th	Night	62% 7% 11% 15% 4	4558
	21st to end	Night	59% 8% 10% 19% 5%	4873
February	1st to 10th	Night	56% 6% 13% 17% 8%	2642
	11th to 20th	Night	47% 8% 14% 19% 11%	2404
	21st to end	Night	48% 6% 14% 22% 10%	1884
March	1st to 10th	Night	55% 6% 14% 17% 6%	2280
	11th to 20th	Night	43% 5% 14% 27% 11% 1	2119
	21st to end	Night	49% 6% 15% 21% 9%	2263
April	1st to 10th	Night	38% 7% 12% 24% 17% 2	1797
	11th to 20th	Night	51% 6% 9% 19% 13% 1	1599
	21st to end	Night	46% 6% 15% 19% 12% 2	1620
May	1st to 10th	Night	41% 7% 13% 25% 14% 1	1576
	11th to 20th	Night	42% 5% 11% 25% 14% 3	1273
	21st to end	Night	44% 5% 13% 22% 15% 1	1358
June	1st to 10th	Night	36% 7% 20% 25% 10% 2	1260
	11th to 20th	Night	39% 8% 15% 26% 11% 2	1260
	21st to end	Night	34% 10% 22% 27% 7% 1	1260
July	1st to 10th	Night	25% 5% 19% 36% 14% 1	1225
	11th to 20th	Night	25% 9% 19% 30% 15% 1	1218
	21st to end	Night	24% 7% 17% 37% 15% 1	1442
August	1st to 10th	Night	27% 8% 17% 33% 13% 1	1424
	11th to 20th	Night	28% 8% 19% 33% 11% 2	1600
	21st to end	Night	30% 6% 13% 33% 16% 2	1782
September	1st to 10th	Night	29% 6% 14% 33% 16% 2	1758
	11th to 20th	Night	35% 6% 17% 27% 14% 1	1980
	21st to end	Night	41% 6% 12% 31% 9% 1	1980
October	1st to 10th	Night	45% 6% 15% 25% 8%	2036
	11th to 20th	Night	44% 5% 12% 28% 10%	2283
	21st to end	Night	49% 6% 15% 25% 6%	2574
November	1st to 10th	Night	51% 7% 14% 18% 8% 2	2462
	11th to 20th	Night	56% 7% 14% 15% 6% 1	2679
	21st to end	Night	55% 7% 15% 17% 6%	2850
December	1st to 10th	Night	57% 7% 15% 15% 6%	2850
	11th to 20th	Night	63% 6% 14% 12% 4	3516
	21st to end	Night	47% 7% 14% 18% 12% 1	5225

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	11% 11% 31% 31% 13% 3	270
	11th to 20th	Day	9% 11% 37% 31% 11% 2	270
	21st to end	Day	15% 9% 31% 30% 12% 2	297
February	1st to 10th	Day	17% 7% 43% 24% 8% 1	270
	11th to 20th	Day	7% 12% 40% 30% 10% 1	270
	21st to end	Day	7% 9% 40% 29% 13% 1	225
March	1st to 10th	Day	17% 12% 29% 29% 9% 3	270
	11th to 20th	Day	12% 13% 30% 29% 14% 2	270
	21st to end	Day	17% 8% 35% 24% 14% 2	330
April	1st to 10th	Day	17% 17% 32% 27% 6% 1	451
	11th to 20th	Day	18% 11% 34% 23% 13% 1	590
	21st to end	Day	17% 12% 32% 26% 11% 2	600
May	1st to 10th	Day	18% 9% 29% 28% 14% 2	603
	11th to 20th	Day	18% 9% 32% 23% 15% 4	625
	21st to end	Day	20% 11% 23% 27% 15% 3	679
June	1st to 10th	Day	16% 10% 28% 26% 15% 6%	630
	11th to 20th	Day	17% 10% 33% 24% 13% 3	630
	21st to end	Day	12% 7% 27% 31% 18% 5%	630
July	1st to 10th	Day	9% 5% 30% 31% 20% 6%	621
	11th to 20th	Day	11% 7% 32% 28% 19% 4	618
	21st to end	Day	6% 6% 25% 35% 22% 7%	684
August	1st to 10th	Day	9% 6% 24% 32% 23% 7%	626
	11th to 20th	Day	12% 6% 23% 28% 23% 8%	615
	21st to end	Day	13% 8% 24% 33% 18% 4	693
September	1st to 10th	Day	13% 8% 35% 29% 12% 3	489
	11th to 20th	Day	19% 6% 28% 33% 11% 3	270
	21st to end	Day	21% 10% 30% 27% 11% 1	270
October	1st to 10th	Day	27% 11% 24% 23% 10% 4	270
	11th to 20th	Day	17% 11% 32% 28% 9% 3	270
	21st to end	Day	25% 8% 36% 23% 6% 2	297
November	1st to 10th	Day	30% 8% 30% 23% 9% 1	270
	11th to 20th	Day	15% 14% 33% 30% 9%	270
	21st to end	Day	17% 11% 39% 28% 4 1	270
December	1st to 10th	Day	17% 7% 35% 27% 11% 3	270
	11th to 20th	Day	14% 13% 41% 27% 4 1	270
	21st to end	Day	12% 5% 37% 33% 10% 3	297
January	1st to 10th	Night	12% 9% 37% 31% 10% 1	950
	11th to 20th	Night	15% 7% 39% 31% 8% 1	950
	21st to end	Night	15% 8% 35% 34% 8% 1	1045
February	1st to 10th	Night	13% 7% 36% 31% 11% 1	950
	11th to 20th	Night	11% 7% 34% 36% 10% 2	929
	21st to end	Night	12% 5% 34% 36% 11% 2	628
March	1st to 10th	Night	15% 7% 30% 34% 12% 2	760
	11th to 20th	Night	10% 9% 36% 31% 13% 2	599
	21st to end	Night	15% 7% 30% 33% 13% 2	627
April	1st to 10th	Night	11% 8% 35% 36% 10% 1	546
	11th to 20th	Night	19% 7% 31% 32% 11% 1	533
	21st to end	Night	16% 6% 32% 34% 10% 1	540
May	1st to 10th	Night	17% 6% 27% 39% 11% 1	540
	11th to 20th	Night	17% 7% 26% 36% 13%	531
	21st to end	Night	21% 7% 27% 33% 11%	584
June	1st to 10th	Night	14% 6% 33% 32% 14% 2	540
	11th to 20th	Night	12% 6% 31% 36% 14% 1	540
	21st to end	Night	11% 6% 24% 39% 19% 1	540
July	1st to 10th	Night	8% 3 26% 42% 21% 1	525
	11th to 20th	Night	7% 5% 28% 40% 18% 1	522
	21st to end	Night	7% 3 22% 46% 19% 3	591
August	1st to 10th	Night	8% 3 24% 43% 21% 1	537
	11th to 20th	Night	8% 4 24% 37% 24% 3	534
	21st to end	Night	12% 6% 23% 42% 16% 2	594
September	1st to 10th	Night	10% 4 29% 37% 17% 2	540
	11th to 20th	Night	14% 7% 27% 42% 10%	540
	21st to end	Night	18% 8% 28% 34% 12% 1	540
October	1st to 10th	Night	18% 7% 34% 31% 10%	596
	11th to 20th	Night	20% 7% 29% 32% 10%	843
	21st to end	Night	17% 11% 35% 28% 9% 1	990
November	1st to 10th	Night	17% 8% 38% 27% 8% 1	925
	11th to 20th	Night	16% 8% 37% 28% 9% 2	950
	21st to end	Night	16% 12% 37% 27% 7% 1	950
December	1st to 10th	Night	11% 9% 35% 33% 10% 2	950
	11th to 20th	Night	17% 9% 35% 28% 8% 2	950
	21st to end	Night	18% 5% 33% 31% 11% 2	1045

Page generated at 2024-03-31 05:08:51. Version ac07

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