Sioux Lookout
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sioux Lookout clear sky chart from 2005-11-06 to 2025-02-25.

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% 11% 4 10% 5% 5% 5% 4 5% 6% 30%	108489
	Night	13% 13% 5% 12% 6% 6% 5% 4 5% 5% 26%	110388
Transparency	Day	53% 6% 13% 20% 8% 1	111951
	Night	58% 6% 11% 17% 7%	115089
Seeing	Day	19% 13% 33% 23% 10% 2	16606
	Night	19% 11% 31% 27% 10% 1	26723

By Month

Percentage Cloud Cover NE (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% 13% 7% 18% 8% 12% 8% 3 5% 4 17%	3178
	11th to 20th	Day	6% 12% 5% 20% 8% 7% 9% 9% 9% 4 12%	3152
	21st to end	Day	7% 17% 9% 21% 7% 6% 5% 4 5% 4 14%	3982
February	1st to 10th	Day	8% 13% 6% 12% 7% 8% 9% 7% 6% 5% 19%	1760
	11th to 20th	Day	7% 11% 4 12% 8% 7% 7% 8% 7% 5% 24%	1754
	21st to end	Day	5% 14% 5% 15% 8% 6% 5% 5% 6% 6% 26%	1492
March	1st to 10th	Day	8% 11% 4 9% 5% 5% 5% 3 4 5% 39%	3166
	11th to 20th	Day	7% 12% 7% 16% 7% 5% 6% 3 4 5% 29%	3480
	21st to end	Day	12% 17% 6% 9% 5% 4 4 3 4 5% 31%	3991
April	1st to 10th	Day	14% 12% 4 9% 6% 4 4 4 5% 6% 33%	2280
	11th to 20th	Day	14% 12% 4 9% 5% 4 3 4 6% 6% 34%	2314
	21st to end	Day	14% 11% 4 7% 4 4 4 5% 5% 6% 36%	2589
May	1st to 10th	Day	15% 10% 3 7% 5% 5% 5% 3 5% 7% 34%	4428
	11th to 20th	Day	15% 9% 4 7% 6% 4 5% 4 5% 7% 34%	4399
	21st to end	Day	22% 9% 3 6% 4 4 4 3 4 6% 35%	4916
June	1st to 10th	Day	18% 6% 2 6% 5% 4 5% 5% 8% 8% 32%	2850
	11th to 20th	Day	18% 7% 2 7% 5% 4 4 5% 7% 9% 33%	2850
	21st to end	Day	16% 6% 2 7% 5% 5% 6% 5% 7% 8% 33%	2850
July	1st to 10th	Day	11% 6% 3 7% 4 5% 5% 4 6% 9% 39%	4750
	11th to 20th	Day	12% 5% 2 5% 3 4 4 4 6% 8% 46%	4750
	21st to end	Day	15% 6% 2 6% 4 4 4 4 6% 8% 41%	4880
August	1st to 10th	Day	18% 5% 2 6% 4 5% 4 4 6% 8% 36%	4423
	11th to 20th	Day	10% 5% 2 5% 3 4 5% 5% 6% 10% 45%	4144
	21st to end	Day	15% 7% 2 6% 4 4 4 4 6% 9% 38%	4383
September	1st to 10th	Day	17% 7% 2 6% 5% 5% 5% 4 4 6% 39%	2280
	11th to 20th	Day	20% 9% 3 8% 5% 5% 6% 4 5% 7% 29%	2280
	21st to end	Day	24% 11% 3 6% 4 4 3 3 4 6% 33%	1998
October	1st to 10th	Day	20% 16% 3 9% 5% 5% 4 3 5% 6% 24%	1900
	11th to 20th	Day	18% 21% 4 11% 6% 4 4 2 5% 5% 20%	1900
	21st to end	Day	21% 22% 7% 12% 4 3 3 2 3 4 18%	1883
November	1st to 10th	Day	16% 22% 5% 11% 6% 5% 4 2 5% 4 19%	1567
	11th to 20th	Day	18% 22% 8% 15% 8% 5% 4 2 3 4 13%	1600
	21st to end	Day	15% 19% 8% 21% 8% 5% 4 3 3 3 10%	1600
December	1st to 10th	Day	13% 17% 7% 18% 15% 9% 5% 3 3 3 7%	2583
	11th to 20th	Day	10% 14% 5% 17% 7% 8% 8% 5% 5% 4 17%	2639
	21st to end	Day	14% 20% 8% 17% 7% 6% 5% 3 4 5% 11%	3498
January	1st to 10th	Night	4 16% 8% 18% 8% 9% 6% 5% 6% 4 17%	6787
	11th to 20th	Night	6% 12% 6% 19% 10% 9% 9% 7% 8% 3 11%	6739
	21st to end	Night	7% 19% 10% 16% 7% 7% 6% 5% 6% 5% 13%	6996
February	1st to 10th	Night	8% 14% 5% 10% 8% 9% 11% 6% 6% 6% 18%	2638
	11th to 20th	Night	8% 12% 4 9% 7% 7% 9% 7% 6% 5% 27%	2533
	21st to end	Night	6% 14% 5% 12% 7% 6% 6% 5% 6% 6% 26%	2057
March	1st to 10th	Night	12% 12% 4 9% 6% 4 5% 4 5% 6% 33%	3704
	11th to 20th	Night	9% 16% 7% 11% 7% 6% 5% 3 5% 4 27%	3479
	21st to end	Night	14% 17% 5% 8% 4 4 4 3 5% 6% 30%	3640
April	1st to 10th	Night	14% 12% 3 9% 5% 4 4 3 5% 5% 36%	1900
	11th to 20th	Night	15% 11% 3 7% 4 4 4 4 6% 5% 37%	1814
	21st to end	Night	13% 11% 4 7% 6% 5% 4 5% 5% 5% 35%	1590
May	1st to 10th	Night	14% 10% 2 7% 4 4 6% 5% 6% 7% 36%	2523
	11th to 20th	Night	16% 9% 3 6% 5% 4 5% 4 5% 7% 37%	2506
	21st to end	Night	27% 8% 3 5% 3 3 4 3 4 6% 34%	2667
June	1st to 10th	Night	19% 9% 2 5% 4 5% 4 4 5% 8% 35%	1330
	11th to 20th	Night	14% 7% 2 6% 5% 5% 5% 4 5% 8% 40%	1330
	21st to end	Night	13% 5% 2 6% 5% 5% 5% 5% 6% 9% 40%	1330
July	1st to 10th	Night	12% 7% 2 5% 4 4 4 4 6% 8% 44%	2220
	11th to 20th	Night	10% 5% 2 5% 4 4 3 4 6% 9% 48%	2220
	21st to end	Night	10% 5% 2 5% 4 4 4 4 6% 9% 46%	2683
August	1st to 10th	Night	17% 6% 3 6% 3 4 4 3 5% 7% 42%	2517
	11th to 20th	Night	11% 5% 2 5% 4 3 4 4 6% 8% 47%	2693
	21st to end	Night	18% 6% 2 6% 4 4 3 4 5% 8% 41%	3278
September	1st to 10th	Night	16% 5% 3 6% 4 5% 4 4 6% 7% 42%	1900
	11th to 20th	Night	21% 8% 3 7% 4 3 3 3 5% 5% 37%	1900
	21st to end	Night	20% 10% 3 6% 5% 4 4 3 5% 5% 35%	2160
October	1st to 10th	Night	19% 13% 4 8% 4 4 4 3 6% 6% 30%	2280
	11th to 20th	Night	22% 15% 4 10% 4 4 4 3 4 6% 25%	2280
	21st to end	Night	21% 18% 5% 11% 6% 4 4 2 4 5% 19%	2713
November	1st to 10th	Night	17% 21% 6% 11% 5% 5% 4 3 4 4 21%	2731
	11th to 20th	Night	18% 18% 6% 16% 8% 6% 5% 3 3 4 14%	2800
	21st to end	Night	16% 21% 8% 15% 9% 6% 4 3 3 4 11%	2800
December	1st to 10th	Night	10% 21% 10% 22% 12% 6% 4 3 2 2 8%	4602
	11th to 20th	Night	10% 14% 6% 15% 9% 9% 8% 5% 5% 5% 15%	5568
	21st to end	Night	12% 20% 7% 18% 8% 6% 5% 3 3 3 14%	7480

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	71% 5% 5% 10% 9% 1	3179
	11th to 20th	Day	68% 4 7% 17% 4	3180
	21st to end	Day	72% 4 5% 10% 8%	3982
February	1st to 10th	Day	63% 6% 9% 13% 8%	1760
	11th to 20th	Day	56% 7% 10% 19% 7% 1	1763
	21st to end	Day	57% 5% 10% 18% 9% 1	1492
March	1st to 10th	Day	45% 7% 12% 19% 16% 1	3168
	11th to 20th	Day	56% 6% 10% 20% 8% 1	3480
	21st to end	Day	54% 6% 8% 19% 12% 1	3991
April	1st to 10th	Day	51% 5% 9% 19% 13% 3	2280
	11th to 20th	Day	50% 5% 10% 23% 11% 1	2314
	21st to end	Day	48% 6% 10% 23% 10% 2	2589
May	1st to 10th	Day	46% 8% 11% 25% 9%	4440
	11th to 20th	Day	46% 9% 13% 19% 11% 1	4403
	21st to end	Day	49% 8% 11% 18% 14% 1	4916
June	1st to 10th	Day	46% 10% 13% 20% 10% 1	2850
	11th to 20th	Day	47% 8% 13% 20% 12%	2850
	21st to end	Day	45% 9% 16% 22% 7% 1	2850
July	1st to 10th	Day	40% 8% 18% 27% 7%	4676
	11th to 20th	Day	33% 7% 21% 32% 6%	4669
	21st to end	Day	41% 7% 15% 31% 5%	4725
August	1st to 10th	Day	44% 7% 15% 26% 8%	4408
	11th to 20th	Day	32% 8% 22% 34% 4	4186
	21st to end	Day	41% 7% 18% 29% 5%	4382
September	1st to 10th	Day	45% 7% 14% 28% 7%	2280
	11th to 20th	Day	53% 9% 17% 19% 3	2280
	21st to end	Day	54% 6% 15% 20% 5%	1998
October	1st to 10th	Day	51% 6% 14% 22% 7%	3160
	11th to 20th	Day	57% 4 16% 17% 5%	3140
	21st to end	Day	63% 5% 19% 12% 1	3072
November	1st to 10th	Day	68% 5% 12% 9% 5% 1	1567
	11th to 20th	Day	79% 4 7% 7% 3	1600
	21st to end	Day	79% 5% 9% 6% 2	1600
December	1st to 10th	Day	83% 4 6% 5% 2	2583
	11th to 20th	Day	69% 5% 7% 11% 8%	2640
	21st to end	Day	75% 4 6% 11% 4	3498
January	1st to 10th	Night	69% 5% 7% 12% 7%	6787
	11th to 20th	Night	73% 5% 8% 12% 3	6786
	21st to end	Night	71% 5% 9% 11% 4	6996
February	1st to 10th	Night	63% 5% 9% 15% 7%	2638
	11th to 20th	Night	55% 7% 11% 19% 7%	2534
	21st to end	Night	55% 7% 11% 19% 7% 1	2057
March	1st to 10th	Night	49% 7% 11% 16% 17% 1	3715
	11th to 20th	Night	58% 9% 11% 15% 6% 1	3480
	21st to end	Night	54% 5% 8% 18% 13% 2	3640
April	1st to 10th	Night	49% 5% 9% 19% 16% 2	1900
	11th to 20th	Night	46% 6% 11% 22% 14% 1	1814
	21st to end	Night	49% 5% 10% 21% 13% 2	1590
May	1st to 10th	Night	43% 9% 12% 22% 13%	2530
	11th to 20th	Night	44% 8% 14% 23% 9% 1	2507
	21st to end	Night	50% 8% 11% 17% 12% 1	2668
June	1st to 10th	Night	45% 8% 14% 20% 12% 1	1330
	11th to 20th	Night	40% 9% 9% 24% 17% 1	1330
	21st to end	Night	38% 10% 16% 27% 8% 1	1330
July	1st to 10th	Night	37% 8% 19% 25% 10%	2185
	11th to 20th	Night	31% 6% 21% 32% 9% 1	2178
	21st to end	Night	35% 8% 16% 35% 6%	2598
August	1st to 10th	Night	41% 6% 14% 31% 7% 1	2508
	11th to 20th	Night	33% 7% 20% 34% 7%	2717
	21st to end	Night	42% 5% 20% 27% 5% 1	3278
September	1st to 10th	Night	41% 7% 17% 26% 10%	1900
	11th to 20th	Night	47% 7% 17% 24% 4	1900
	21st to end	Night	51% 6% 16% 21% 5%	2160
October	1st to 10th	Night	46% 7% 14% 25% 7%	3800
	11th to 20th	Night	55% 5% 14% 21% 4	3779
	21st to end	Night	61% 6% 17% 14% 3	4475
November	1st to 10th	Night	67% 6% 11% 12% 3	2731
	11th to 20th	Night	76% 5% 9% 8% 2	2800
	21st to end	Night	79% 5% 8% 7% 2	2800
December	1st to 10th	Night	84% 3 6% 4 1	4602
	11th to 20th	Night	69% 6% 10% 10% 5%	5566
	21st to end	Night	76% 4 5% 13% 3	7480

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	14% 12% 38% 26% 9% 1	300
	11th to 20th	Day	14% 10% 35% 31% 9% 1	300
	21st to end	Day	16% 11% 39% 25% 9% 1	330
February	1st to 10th	Day	15% 14% 43% 21% 6%	300
	11th to 20th	Day	13% 18% 35% 22% 10% 1	300
	21st to end	Day	15% 22% 40% 16% 5% 2	237
March	1st to 10th	Day	11% 14% 43% 24% 6% 1	270
	11th to 20th	Day	11% 22% 40% 20% 5% 2	270
	21st to end	Day	18% 13% 35% 21% 10% 2	397
April	1st to 10th	Day	19% 15% 33% 23% 10% 1	460
	11th to 20th	Day	23% 15% 29% 22% 11%	512
	21st to end	Day	20% 12% 34% 23% 10% 2	650
May	1st to 10th	Day	20% 17% 33% 21% 7% 2	653
	11th to 20th	Day	22% 15% 29% 23% 10% 2	675
	21st to end	Day	25% 11% 31% 23% 9% 1	734
June	1st to 10th	Day	21% 13% 31% 23% 9% 4	680
	11th to 20th	Day	19% 14% 37% 20% 8% 2	680
	21st to end	Day	17% 10% 31% 24% 13% 4	680
July	1st to 10th	Day	13% 13% 31% 24% 14% 5%	671
	11th to 20th	Day	16% 13% 28% 24% 16% 4	668
	21st to end	Day	12% 9% 29% 29% 13% 7%	739
August	1st to 10th	Day	14% 9% 31% 30% 13% 3	676
	11th to 20th	Day	15% 8% 26% 29% 17% 4	665
	21st to end	Day	20% 11% 31% 24% 13% 1	664
September	1st to 10th	Day	19% 14% 32% 23% 11% 2	490
	11th to 20th	Day	23% 12% 29% 26% 8% 1	490
	21st to end	Day	28% 12% 34% 19% 7% 1	355
October	1st to 10th	Day	28% 17% 26% 23% 5% 2	300
	11th to 20th	Day	24% 16% 36% 19% 3 1	300
	21st to end	Day	35% 15% 36% 11% 3	330
November	1st to 10th	Day	26% 16% 32% 19% 6% 1	300
	11th to 20th	Day	29% 18% 33% 15% 5%	300
	21st to end	Day	25% 22% 36% 14% 3	300
December	1st to 10th	Day	16% 16% 38% 24% 4 2	300
	11th to 20th	Day	19% 16% 37% 24% 3	300
	21st to end	Day	18% 14% 33% 25% 7% 4	330
January	1st to 10th	Night	14% 13% 36% 28% 9% 1	1000
	11th to 20th	Night	16% 10% 37% 29% 7% 1	1000
	21st to end	Night	17% 11% 35% 28% 8% 1	1100
February	1st to 10th	Night	14% 13% 37% 29% 8% 1	1000
	11th to 20th	Night	13% 12% 32% 27% 12% 2	979
	21st to end	Night	10% 14% 33% 29% 12% 3	765
March	1st to 10th	Night	15% 14% 33% 27% 10% 1	755
	11th to 20th	Night	17% 14% 34% 23% 9% 2	570
	21st to end	Night	21% 12% 27% 27% 9% 4	627
April	1st to 10th	Night	19% 11% 28% 33% 9%	570
	11th to 20th	Night	19% 11% 30% 28% 10% 1	563
	21st to end	Night	17% 10% 28% 33% 10% 2	570
May	1st to 10th	Night	21% 11% 31% 29% 7% 1	570
	11th to 20th	Night	23% 11% 31% 25% 10% 1	561
	21st to end	Night	24% 6% 29% 31% 9%	617
June	1st to 10th	Night	22% 7% 27% 30% 14% 2	570
	11th to 20th	Night	14% 11% 30% 32% 12% 1	570
	21st to end	Night	15% 7% 22% 38% 17% 1	570
July	1st to 10th	Night	10% 7% 28% 34% 19% 1	555
	11th to 20th	Night	13% 7% 28% 33% 17% 3	552
	21st to end	Night	14% 4 24% 34% 21% 3	624
August	1st to 10th	Night	14% 6% 27% 34% 18% 1	567
	11th to 20th	Night	16% 8% 18% 33% 21% 4	564
	21st to end	Night	19% 6% 30% 28% 16%	627
September	1st to 10th	Night	18% 8% 28% 31% 14% 1	570
	11th to 20th	Night	25% 9% 27% 27% 11% 1	570
	21st to end	Night	25% 10% 28% 27% 9% 1	697
October	1st to 10th	Night	26% 14% 29% 24% 6%	760
	11th to 20th	Night	31% 12% 27% 23% 7% 1	760
	21st to end	Night	30% 13% 31% 20% 5% 1	845
November	1st to 10th	Night	26% 16% 31% 21% 6% 2	975
	11th to 20th	Night	27% 13% 33% 21% 5% 1	1000
	21st to end	Night	27% 18% 33% 19% 3 1	1000
December	1st to 10th	Night	15% 13% 40% 24% 6% 2	1000
	11th to 20th	Night	19% 13% 36% 24% 7% 1	1000
	21st to end	Night	21% 11% 31% 25% 10% 2	1100

Page generated at 2025-02-22 05:51:35. Version ac07

Copyright © 2025 Attilla Danko.