Regina
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Regina clear sky chart from 2005-11-06 to 2025-09-04.

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	9% 8% 3 8% 5% 5% 5% 4 6% 8% 38%	130109
	Night	8% 9% 4 9% 6% 6% 6% 4 6% 7% 36%	127364
Transparency	Day	43% 7% 16% 24% 10% 1	129825
	Night	45% 6% 16% 23% 9% 1	127228
Seeing	Day	12% 9% 31% 29% 15% 3	17214
	Night	12% 7% 31% 35% 12% 1	26567

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	6% 15% 5% 15% 9% 9% 8% 5% 6% 6% 16%	3179
	11th to 20th	Day	3 8% 3 11% 10% 8% 9% 10% 12% 8% 18%	3589
	21st to end	Day	5% 11% 6% 14% 6% 6% 5% 4 5% 7% 31%	4004
February	1st to 10th	Day	7% 14% 6% 13% 7% 8% 7% 5% 6% 7% 19%	1645
	11th to 20th	Day	7% 12% 5% 10% 7% 8% 8% 6% 7% 5% 25%	1755
	21st to end	Day	5% 11% 5% 13% 11% 7% 7% 5% 7% 6% 23%	1616
March	1st to 10th	Day	6% 12% 5% 14% 7% 5% 6% 4 5% 8% 26%	4500
	11th to 20th	Day	5% 12% 7% 15% 6% 5% 4 4 5% 7% 29%	4758
	21st to end	Day	9% 12% 5% 14% 6% 5% 5% 4 5% 6% 28%	5915
April	1st to 10th	Day	6% 8% 4 7% 5% 5% 5% 5% 8% 9% 37%	2400
	11th to 20th	Day	13% 13% 4 10% 6% 6% 4 4 6% 7% 28%	2404
	21st to end	Day	13% 10% 3 7% 6% 4 5% 3 5% 6% 37%	2757
May	1st to 10th	Day	15% 8% 2 5% 3 3 4 3 6% 7% 43%	6340
	11th to 20th	Day	16% 8% 2 6% 5% 5% 6% 5% 8% 8% 30%	6298
	21st to end	Day	12% 6% 2 6% 5% 5% 5% 4 6% 7% 45%	7104
June	1st to 10th	Day	15% 5% 3 6% 5% 5% 5% 5% 6% 8% 37%	3095
	11th to 20th	Day	18% 8% 3 7% 5% 5% 6% 4 5% 7% 32%	3200
	21st to end	Day	11% 6% 2 5% 5% 5% 5% 4 7% 9% 42%	3200
July	1st to 10th	Day	5% 4 2 5% 5% 5% 5% 5% 8% 10% 47%	7024
	11th to 20th	Day	8% 4 2 6% 4 5% 5% 5% 7% 10% 43%	6560
	21st to end	Day	5% 3 2 5% 4 4 4 4 6% 8% 56%	6898
August	1st to 10th	Day	9% 5% 2 5% 4 4 5% 3 6% 7% 49%	4552
	11th to 20th	Day	6% 4 2 5% 4 4 4 4 7% 10% 50%	4483
	21st to end	Day	9% 4 2 6% 3 3 4 4 5% 7% 54%	4391
September	1st to 10th	Day	11% 5% 3 5% 4 3 5% 3 5% 7% 49%	2317
	11th to 20th	Day	12% 8% 3 6% 4 4 4 3 5% 8% 44%	2263
	21st to end	Day	13% 5% 2 5% 4 3 4 3 5% 8% 48%	2067
October	1st to 10th	Day	9% 8% 2 6% 5% 5% 5% 4 6% 7% 42%	3170
	11th to 20th	Day	7% 7% 2 5% 3 3 4 4 7% 10% 49%	3006
	21st to end	Day	7% 10% 4 9% 5% 4 4 4 6% 8% 38%	3091
November	1st to 10th	Day	12% 16% 4 9% 7% 4 4 3 5% 5% 31%	1649
	11th to 20th	Day	7% 13% 5% 14% 7% 7% 5% 4 6% 6% 28%	1600
	21st to end	Day	9% 13% 6% 10% 6% 6% 7% 4 6% 6% 27%	1432
December	1st to 10th	Day	5% 13% 5% 14% 8% 8% 8% 4 6% 6% 23%	2290
	11th to 20th	Day	7% 16% 7% 14% 8% 8% 6% 5% 5% 6% 17%	2565
	21st to end	Day	5% 7% 5% 12% 9% 5% 5% 6% 4 5% 37%	2992
January	1st to 10th	Night	3 12% 5% 13% 9% 8% 8% 5% 7% 8% 21%	6766
	11th to 20th	Night	4 9% 4 13% 9% 10% 9% 6% 9% 6% 21%	6324
	21st to end	Night	5% 11% 6% 12% 8% 6% 5% 4 6% 7% 31%	6974
February	1st to 10th	Night	8% 11% 5% 11% 7% 8% 7% 5% 8% 7% 23%	2774
	11th to 20th	Night	5% 11% 4 11% 7% 6% 8% 5% 7% 8% 28%	2532
	21st to end	Night	4 8% 3 12% 8% 7% 6% 4 7% 9% 32%	2013
March	1st to 10th	Night	6% 10% 5% 14% 7% 6% 6% 5% 6% 8% 27%	5374
	11th to 20th	Night	7% 11% 4 10% 8% 7% 6% 5% 6% 8% 29%	5230
	21st to end	Night	8% 12% 5% 16% 7% 6% 5% 4 6% 7% 26%	5040
April	1st to 10th	Night	7% 9% 3 6% 4 5% 5% 3 8% 7% 43%	2000
	11th to 20th	Night	13% 11% 4 7% 5% 5% 5% 4 6% 8% 33%	1947
	21st to end	Night	13% 8% 3 8% 5% 4 6% 5% 6% 7% 35%	1640
May	1st to 10th	Night	13% 9% 3 6% 4 4 3 3 6% 7% 43%	3640
	11th to 20th	Night	17% 7% 3 7% 5% 4 5% 4 6% 7% 34%	3618
	21st to end	Night	13% 6% 2 5% 3 4 4 3 5% 7% 47%	3793
June	1st to 10th	Night	12% 5% 2 4 4 4 4 5% 7% 8% 45%	1300
	11th to 20th	Night	15% 6% 3 5% 4 3 5% 4 6% 8% 41%	1200
	21st to end	Night	9% 5% 2 5% 4 4 4 4 8% 9% 45%	1200
July	1st to 10th	Night	6% 5% 2 4 4 4 5% 4 7% 11% 49%	2918
	11th to 20th	Night	10% 5% 2 6% 4 4 4 4 6% 8% 50%	3410
	21st to end	Night	5% 3 2 3 3 3 3 3 5% 7% 62%	3968
August	1st to 10th	Night	7% 4 2 5% 3 3 4 4 5% 7% 55%	2608
	11th to 20th	Night	4 3 1 5% 4 4 5% 4 7% 9% 52%	2576
	21st to end	Night	6% 4 2 6% 4 4 4 4 5% 8% 54%	3514
September	1st to 10th	Night	9% 4 1 5% 4 4 5% 3 6% 7% 53%	1930
	11th to 20th	Night	10% 6% 2 6% 4 4 5% 3 5% 8% 49%	1916
	21st to end	Night	10% 6% 2 5% 4 3 4 4 6% 6% 50%	2109
October	1st to 10th	Night	10% 7% 3 6% 3 4 4 3 5% 8% 47%	3800
	11th to 20th	Night	6% 6% 2 5% 4 4 4 4 6% 10% 50%	3891
	21st to end	Night	8% 8% 3 8% 5% 4 5% 4 5% 7% 43%	4467
November	1st to 10th	Night	15% 13% 4 9% 6% 4 5% 3 4 7% 31%	2647
	11th to 20th	Night	8% 12% 4 12% 8% 6% 6% 4 6% 6% 28%	2800
	21st to end	Night	8% 12% 5% 12% 6% 5% 5% 4 5% 7% 30%	2965
December	1st to 10th	Night	7% 14% 5% 15% 9% 8% 7% 4 5% 5% 20%	4900
	11th to 20th	Night	7% 14% 6% 13% 9% 8% 8% 4 5% 6% 20%	5634
	21st to end	Night	4 7% 4 11% 8% 7% 7% 4 7% 6% 36%	7946

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	66% 6% 12% 11% 5%	3179
	11th to 20th	Day	54% 7% 17% 14% 8%	3613
	21st to end	Day	53% 6% 21% 18% 3	4004
February	1st to 10th	Day	62% 6% 10% 14% 7%	1645
	11th to 20th	Day	57% 6% 11% 15% 11% 1	1764
	21st to end	Day	57% 8% 13% 14% 8%	1616
March	1st to 10th	Day	55% 6% 18% 16% 5%	4500
	11th to 20th	Day	54% 8% 17% 17% 4	4759
	21st to end	Day	53% 8% 13% 17% 8% 1	5915
April	1st to 10th	Day	39% 9% 18% 23% 10% 1	2400
	11th to 20th	Day	54% 7% 12% 18% 6% 2	2404
	21st to end	Day	47% 5% 17% 22% 8% 1	2757
May	1st to 10th	Day	39% 5% 13% 25% 16% 2	6340
	11th to 20th	Day	45% 8% 14% 23% 10%	6302
	21st to end	Day	35% 7% 12% 27% 18% 1	7104
June	1st to 10th	Day	41% 7% 15% 26% 9% 1	3095
	11th to 20th	Day	50% 8% 13% 19% 10% 1	3200
	21st to end	Day	36% 9% 18% 28% 9%	3200
July	1st to 10th	Day	29% 9% 24% 28% 10%	6949
	11th to 20th	Day	34% 8% 17% 32% 9%	6480
	21st to end	Day	25% 7% 17% 35% 14% 2	6705
August	1st to 10th	Day	32% 7% 19% 25% 16% 1	4536
	11th to 20th	Day	28% 7% 19% 37% 9% 1	4525
	21st to end	Day	30% 6% 15% 38% 11% 1	4390
September	1st to 10th	Day	33% 6% 14% 29% 15% 2	2317
	11th to 20th	Day	39% 5% 15% 27% 11% 2	2263
	21st to end	Day	34% 5% 15% 31% 13% 2	2067
October	1st to 10th	Day	39% 5% 16% 29% 10% 1	3170
	11th to 20th	Day	30% 4 17% 36% 10% 2	3006
	21st to end	Day	43% 5% 17% 27% 7%	3091
November	1st to 10th	Day	55% 6% 16% 16% 7%	1649
	11th to 20th	Day	56% 7% 14% 16% 7% 1	1600
	21st to end	Day	57% 8% 16% 15% 4	1432
December	1st to 10th	Day	60% 7% 18% 11% 4	2290
	11th to 20th	Day	67% 7% 17% 8% 2	2566
	21st to end	Day	48% 4 10% 22% 11% 5%	2992
January	1st to 10th	Night	58% 7% 14% 17% 4	6766
	11th to 20th	Night	58% 6% 15% 14% 7%	6362
	21st to end	Night	52% 7% 21% 17% 3	6974
February	1st to 10th	Night	56% 6% 13% 17% 7%	2774
	11th to 20th	Night	50% 6% 14% 19% 11% 1	2533
	21st to end	Night	46% 6% 17% 22% 8%	2013
March	1st to 10th	Night	50% 6% 23% 16% 4	5374
	11th to 20th	Night	50% 7% 19% 19% 4	5230
	21st to end	Night	56% 6% 11% 19% 7%	5040
April	1st to 10th	Night	36% 6% 15% 26% 17% 1	2000
	11th to 20th	Night	48% 6% 11% 22% 10% 3	1947
	21st to end	Night	45% 8% 11% 25% 11% 1	1640
May	1st to 10th	Night	39% 5% 11% 26% 17% 2	3640
	11th to 20th	Night	46% 7% 15% 19% 11% 2	3618
	21st to end	Night	34% 8% 12% 27% 19% 1	3793
June	1st to 10th	Night	33% 6% 15% 29% 14% 2	1300
	11th to 20th	Night	40% 8% 18% 21% 13% 1	1200
	21st to end	Night	33% 8% 19% 30% 10% 1	1200
July	1st to 10th	Night	28% 8% 26% 32% 6%	2884
	11th to 20th	Night	32% 6% 14% 35% 11% 1	3367
	21st to end	Night	22% 5% 19% 34% 15% 4	3856
August	1st to 10th	Night	27% 7% 20% 29% 16% 1	2600
	11th to 20th	Night	25% 7% 17% 38% 12% 1	2600
	21st to end	Night	27% 6% 15% 36% 14% 1	3514
September	1st to 10th	Night	29% 7% 11% 30% 21% 3	1930
	11th to 20th	Night	33% 7% 16% 28% 16% 1	1916
	21st to end	Night	34% 6% 13% 30% 15% 2	2109
October	1st to 10th	Night	36% 4 16% 32% 9% 2	3800
	11th to 20th	Night	30% 4 15% 37% 12% 1	3891
	21st to end	Night	39% 4 13% 33% 11%	4467
November	1st to 10th	Night	54% 7% 13% 17% 7% 1	2647
	11th to 20th	Night	55% 7% 18% 15% 5%	2800
	21st to end	Night	53% 6% 18% 19% 4	2965
December	1st to 10th	Night	65% 7% 14% 10% 3	4900
	11th to 20th	Night	65% 6% 16% 10% 3	5632
	21st to end	Night	45% 6% 11% 21% 13% 4	7946

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% 9% 37% 24% 15% 4	200
	11th to 20th	Day	8% 10% 35% 34% 12% 2	294
	21st to end	Day	12% 10% 38% 29% 11% 1	330
February	1st to 10th	Day	15% 10% 38% 26% 10% 1	300
	11th to 20th	Day	11% 8% 33% 29% 15% 3	300
	21st to end	Day	7% 7% 33% 38% 14% 1	249
March	1st to 10th	Day	13% 7% 36% 30% 12% 2	300
	11th to 20th	Day	11% 11% 38% 28% 9% 3	389
	21st to end	Day	13% 13% 31% 28% 13% 1	550
April	1st to 10th	Day	9% 15% 38% 29% 7% 2	500
	11th to 20th	Day	19% 15% 32% 25% 9% 1	522
	21st to end	Day	16% 10% 29% 30% 15% 1	700
May	1st to 10th	Day	13% 8% 30% 29% 17% 2	703
	11th to 20th	Day	14% 9% 27% 29% 14% 6%	725
	21st to end	Day	16% 9% 25% 28% 18% 5%	789
June	1st to 10th	Day	15% 12% 30% 23% 16% 4	730
	11th to 20th	Day	18% 14% 31% 23% 12% 2	730
	21st to end	Day	12% 8% 27% 30% 21% 3	730
July	1st to 10th	Day	7% 5% 25% 37% 20% 6%	721
	11th to 20th	Day	8% 8% 29% 29% 20% 6%	718
	21st to end	Day	5% 7% 27% 31% 21% 8%	794
August	1st to 10th	Day	10% 6% 22% 37% 19% 6%	726
	11th to 20th	Day	9% 5% 23% 33% 24% 5%	715
	21st to end	Day	10% 9% 22% 32% 23% 4	590
September	1st to 10th	Day	13% 12% 31% 28% 14% 2	503
	11th to 20th	Day	17% 9% 30% 28% 14% 1	473
	21st to end	Day	14% 9% 34% 29% 11% 2	300
October	1st to 10th	Day	18% 9% 30% 24% 15% 3	300
	11th to 20th	Day	11% 12% 36% 27% 13% 2	300
	21st to end	Day	14% 13% 38% 25% 7% 2	330
November	1st to 10th	Day	18% 8% 34% 26% 12% 2	300
	11th to 20th	Day	14% 9% 42% 29% 5%	300
	21st to end	Day	12% 10% 37% 31% 9% 1	300
December	1st to 10th	Day	12% 10% 34% 32% 10% 2	300
	11th to 20th	Day	12% 9% 49% 22% 8%	283
	21st to end	Day	11% 6% 35% 34% 10% 3	220
January	1st to 10th	Night	8% 10% 36% 33% 11% 2	1000
	11th to 20th	Night	13% 11% 35% 34% 7% 1	1000
	21st to end	Night	10% 11% 39% 29% 9% 1	1100
February	1st to 10th	Night	13% 7% 34% 33% 12% 1	974
	11th to 20th	Night	9% 6% 35% 38% 10% 2	784
	21st to end	Night	6% 6% 27% 39% 19% 3	660
March	1st to 10th	Night	11% 7% 35% 33% 12% 1	800
	11th to 20th	Night	10% 8% 35% 33% 13% 1	800
	21st to end	Night	13% 6% 31% 36% 13% 1	690
April	1st to 10th	Night	11% 9% 33% 36% 12% 1	600
	11th to 20th	Night	18% 9% 33% 33% 7% 1	593
	21st to end	Night	17% 8% 31% 37% 6%	600
May	1st to 10th	Night	15% 8% 27% 38% 13% 1	600
	11th to 20th	Night	15% 8% 28% 32% 15% 1	591
	21st to end	Night	18% 5% 27% 34% 15% 2	650
June	1st to 10th	Night	13% 6% 30% 35% 15% 1	500
	11th to 20th	Night	20% 6% 26% 39% 10% 1	400
	21st to end	Night	13% 6% 24% 41% 16% 1	400
July	1st to 10th	Night	9% 2 28% 39% 20% 2	390
	11th to 20th	Night	9% 4 26% 44% 17%	487
	21st to end	Night	6% 4 25% 42% 20% 2	657
August	1st to 10th	Night	8% 4 26% 41% 20% 2	597
	11th to 20th	Night	6% 5% 23% 41% 25% 2	594
	21st to end	Night	10% 5% 26% 39% 19% 1	660
September	1st to 10th	Night	10% 6% 26% 37% 19% 2	579
	11th to 20th	Night	14% 6% 25% 39% 15% 1	570
	21st to end	Night	11% 7% 31% 40% 10% 1	589
October	1st to 10th	Night	19% 6% 25% 35% 15% 1	760
	11th to 20th	Night	13% 7% 29% 38% 13% 1	822
	21st to end	Night	17% 9% 31% 34% 9% 1	1045
November	1st to 10th	Night	20% 8% 33% 30% 8% 1	975
	11th to 20th	Night	13% 11% 34% 31% 10% 1	1000
	21st to end	Night	13% 9% 38% 33% 7% 1	1000
December	1st to 10th	Night	12% 7% 36% 31% 11% 3	1000
	11th to 20th	Night	12% 12% 34% 32% 9% 1	1000
	21st to end	Night	12% 5% 34% 34% 13% 2	1100

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